Commit Graph

5203 Commits

Author SHA1 Message Date
David Majnemer bf7550e7ec InstSimplify: Exact shifts of X by Y are X if X has the lsb set
Exact shifts may not shift out any non-zero bits. Use computeKnownBits
to determine when this occurs and just return the left hand side.

This fixes PR21477.

llvm-svn: 221325
2014-11-05 00:59:59 +00:00
David Majnemer f20d7c4c61 Analysis: Make isSafeToSpeculativelyExecute fire less for divides
Divides and remainder operations do not behave like other operations
when they are given poison: they turn into undefined behavior.

It's really hard to know if the operands going into a div are or are not
poison.  Because of this, we should only choose to speculate if there
are constant operands which we can easily reason about.

This fixes PR21412.

llvm-svn: 221318
2014-11-04 23:49:08 +00:00
David Majnemer 2de97fcd9a InstSimplify: Fold a hasNoSignedWrap() call into a match() expression
No functionality change intended, it's just a little more concise.

llvm-svn: 221281
2014-11-04 17:47:13 +00:00
David Majnemer 4f438377fb InstSimplify: Fold a hasNoUnsignedWrap() call into a match() expression
No functionality change intended, it's just a little more concise.

llvm-svn: 221280
2014-11-04 17:38:50 +00:00
Sanjay Patel aee8421088 remove function names from comments; NFC
llvm-svn: 221274
2014-11-04 16:27:42 +00:00
Sanjay Patel 547e9752ff fix typo in comment
llvm-svn: 221273
2014-11-04 16:09:50 +00:00
Hal Finkel 840257a49c Use AA in LoadCombine
LoadCombine can be smarter about aborting when a writing instruction is
encountered, instead of aborting upon encountering any writing instruction, use
an AliasSetTracker, and only abort when encountering some write that might
alias with the loads that could potentially be combined.

This was originally motivated by comments made (and a test case provided) by
David Majnemer in response to PR21448. It turned out that LoadCombine was not
responsible for that PR, but LoadCombine should also be improved so that
unrelated stores (and @llvm.assume) don't interrupt load combining.

llvm-svn: 221203
2014-11-03 23:19:16 +00:00
Duncan P. N. Exon Smith 3872d0084c IR: MDNode => Value: Instruction::getMetadata()
Change `Instruction::getMetadata()` to return `Value` as part of
PR21433.

Update most callers to use `Instruction::getMDNode()`, which wraps the
result in a `cast_or_null<MDNode>`.

llvm-svn: 221024
2014-11-01 00:10:31 +00:00
Bradley Smith 9992b167ae [SCEV] Improve Scalar Evolution's use of no {un,}signed wrap flags
In a case where we have a no {un,}signed wrap flag on the increment, if
RHS - Start is constant then we can avoid inserting a max operation bewteen
the two, since we can statically determine which is greater.

This allows us to unroll loops such as:

 void testcase3(int v) {
   for (int i=v; i<=v+1; ++i)
     f(i);
 }

llvm-svn: 220960
2014-10-31 11:40:32 +00:00
Philip Reames 4cb4d3e048 Add handling for range metadata in ValueTracking isKnownNonZero
If we load from a location with range metadata, we can use information about the ranges of the loaded value for optimization purposes.  This helps to remove redundant checks and canonicalize checks for other optimization passes.  This particular patch checks whether a value is known to be non-zero from the range metadata.

Currently, these tests are against InstCombine.  In theory, all of these should be InstSimplify since we're not inserting any new instructions.  Moving the code may follow in a separate change.

Reviewed by: Hal
Differential Revision: http://reviews.llvm.org/D5947

llvm-svn: 220925
2014-10-30 20:25:19 +00:00
NAKAMURA Takumi d0e13af22c Reformat partially, where I touched for whitespace changes.
llvm-svn: 220773
2014-10-28 11:54:52 +00:00
NAKAMURA Takumi 335a7bcf1e Untabify and whitespace cleanups.
llvm-svn: 220771
2014-10-28 11:53:30 +00:00
Benjamin Kramer 63207bc9c3 Clean up assume intrinsic pattern matching, no need to check that the argument is a value.
Also make it const safe and remove superfluous casting. NFC.

llvm-svn: 220616
2014-10-25 18:09:01 +00:00
Bruno Cardoso Lopes c29520c5b3 [InstSimplify] Support constant folding to vector of pointers
ConstantFolding crashes when trying to InstSimplify the following load:

@a = private unnamed_addr constant %mst {
     i8* inttoptr (i64 -1 to i8*),
     i8* inttoptr (i64 -1 to i8*)
}, align 8

%x = load <2 x i8*>* bitcast (%mst* @a to <2 x i8*>*), align 8

This patch fix this by adding support to this type of folding:

%x = load <2 x i8*>* bitcast (%mst* @a to <2 x i8*>*), align 8
==> gets folded to:
  %x = <2 x i8*> <i8* inttoptr (i64 -1 to i8*), i8* inttoptr (i64 -1 to i8*)>

llvm-svn: 220380
2014-10-22 12:18:48 +00:00
Hans Wennborg 0b39fc0d16 Revert "Teach the load analysis to allow finding available values which require" (r220277)
This seems to have caused PR21330.

llvm-svn: 220349
2014-10-21 23:49:52 +00:00
Matt Arsenault d6511b49ac Add minnum / maxnum intrinsics
These are named following the IEEE-754 names for these
functions, rather than the libm fmin / fmax to avoid
possible ambiguities. Some languages may implement something
resembling fmin / fmax which return NaN if either operand is
to propagate errors. These implement the IEEE-754 semantics
of returning the other operand if either is a NaN representing
missing data.

llvm-svn: 220341
2014-10-21 23:00:20 +00:00
Sanjay Patel d5aa255146 remove function names from comments; NFC
llvm-svn: 220309
2014-10-21 18:26:57 +00:00
Chandler Carruth aa72a6dd3b Teach the load analysis to allow finding available values which require
inttoptr or ptrtoint cast provided there is datalayout available.
Eventually, the datalayout can just be required but in practice it will
always be there today.

To go with the ability to expose available values requiring a ptrtoint
or inttoptr cast, helpers are added to perform one of these three casts.

These smarts are necessary to finish canonicalizing loads and stores to
the operational type requirements without regressing fundamental
combines.

I've added some test cases. These should actually improve as the load
combining and store combining improves, but they may fundamentally be
highlighting some missing combines for select in addition to exercising
the specific added logic to load analysis.

llvm-svn: 220277
2014-10-21 09:00:40 +00:00
Philip Reames 5a3f5f751b Introduce enum values for previously defined metadata types. (NFC)
Our metadata scheme lazily assigns IDs to string metadata, but we have a mechanism to preassign them as well.  Using a preassigned ID is helpful since we get compile time type checking, and avoid some (minimal) string construction and comparison.  This change adds enum value for three existing metadata types:
+    MD_nontemporal = 9, // "nontemporal"
+    MD_mem_parallel_loop_access = 10, // "llvm.mem.parallel_loop_access"
+    MD_nonnull = 11 // "nonnull"

I went through an updated various uses as well.  I made no attempt to get all uses; I focused on the ones which were easily grepable and easily to translate.  For example, there were several items in LoopInfo.cpp I chose not to update.

llvm-svn: 220248
2014-10-21 00:13:20 +00:00
Philip Reames cdb72f369f Introduce a 'nonnull' metadata on Load instructions.
The newly introduced 'nonnull' metadata is analogous to existing 'nonnull' attributes, but applies to load instructions rather than call arguments or returns.  Long term, it would be nice to combine these into a single construct.   The value of the load is allowed to vary between successive loads, but null is not a valid value to be loaded by any load marked nonnull.

Reviewed by: Hal Finkel
Differential Revision:  http://reviews.llvm.org/D5220

llvm-svn: 220240
2014-10-20 22:40:55 +00:00
Chandler Carruth a32038b006 Fix a miscompile introduced in r220178.
The original code had an implicit assumption that if the test for
allocas or globals was reached, the two pointers were not equal. With my
changes to make the pointer analysis more powerful here, I also had to
guard against circumstances where the results weren't useful. That in
turn violated the assumption and gave rise to a circumstance in which we
could have a store with both the queried pointer and stored pointer
rooted at *the same* alloca. Clearly, we cannot ignore such a store.
There are other things we might do in this code to better handle the
case of both pointers ending up at the same alloca or global, but it
seems best to at least make the test explicit in what it intends to
check.

I've added tests for both the alloca and global case here.

llvm-svn: 220190
2014-10-20 10:03:01 +00:00
Chandler Carruth eeec35ae1c Teach the load analysis driving core instcombine logic and other bits of
logic to look through pointer casts, making them trivially stronger in
the face of loads and stores with intervening pointer casts.

I've included a few test cases that demonstrate the kind of folding
instcombine can do without pointer casts and then variations which
obfuscate the logic through bitcasts. Without this patch, the variations
all fail to optimize fully.

This is more important now than it has been in the past as I've started
moving the load canonicialization to more closely follow the value type
requirements rather than the pointer type requirements and thus this
needs to be prepared for more pointer casts. When I made the same change
to stores several test cases regressed without logic along these lines
so I wanted to systematically improve matters first.

llvm-svn: 220178
2014-10-20 00:24:14 +00:00
Chandler Carruth 5b8cd2f73c Move previously dead code to handle computing the known bits of an alias
up to where it actually works as intended. The problem is that
a GlobalAlias isa GlobalValue and so the prior block handled all of the
cases.

This allows us to constant fold based on the actual constant expression
in the global alias. As an example, see the last function in the newly
added test case which explicitly aligns an unaligned pointer using
constant expression math. Without this change, we fail to see that and
fold an alignment test to zero.

llvm-svn: 220164
2014-10-19 09:06:56 +00:00
Chandler Carruth a801dd5799 Fix a long-standing miscompile in the load analysis that was uncovered
by my refactoring of this code.

The method isSafeToLoadUnconditionally assumes that the load will
proceed with the preferred type alignment. Given that, it has to ensure
that the alloca or global is at least that aligned. It has always done
this historically when a datalayout is present, but has never checked it
when the datalayout is absent. When I refactored the code in r220156,
I exposed this path when datalayout was present and that turned the
latent bug into a patent bug.

This fixes the issue by just removing the special case which allows
folding things without datalayout. This isn't worth the complexity of
trying to tease apart when it is or isn't safe without actually knowing
the preferred alignment.

llvm-svn: 220161
2014-10-19 08:17:50 +00:00
Chandler Carruth 8a99373812 Switch how the datalayout availability test is handled in this code to
make much more sense and in theory be more correct.

If you trace the code alllll the way back to when it was first
introduced, the comments make it slightly more clear what was going on
here. At that time, the only way Base != V was if DL (then TD) was
non-null. As a consequence, if DL *was* null, that meant we were loading
directly from the alloca or global found above the test. After
refactoring, this has become at least terribly subtle and potentially
incorrect. There are many forms of pointer manipulation that can be
traversed without DataLayout, and some of them would in fact change the
size of object being loaded vs. allocated.

Rather than this subtlety, I've hoisted the actual 'return true' bits
into the code which actually found an alloca or global and based them on
the loaded pointer being that alloca or global. This is both more clear
and safer. I've also added comments about exactly why this set of
predicates is used.

I've also corrected a misleading comment about globals -- if overridden
they may not just have a different size, they may be null and completely
unsafe to load from!

Hopefully this confuses the next reader a bit less. I don't have any
test cases or anything, the patch is motivated strictly to improve the
readability of the code.

llvm-svn: 220156
2014-10-19 00:42:16 +00:00
Chandler Carruth 38e98d5782 Rename 'TD' to 'DL' in this function as the argument is now a DataLayout
argument.

llvm-svn: 220151
2014-10-18 23:47:22 +00:00
Chandler Carruth 1f27f03849 Fix the other comment to use modern doxygen style and be a bit more
direct. Notably, comment on the fact that the loaded type is significant
in that it determines how wide of an access must be safe.

llvm-svn: 220150
2014-10-18 23:46:17 +00:00
Chandler Carruth be49df3d2c More formatting cleanup brought to you by clang-format.
llvm-svn: 220149
2014-10-18 23:41:25 +00:00
Chandler Carruth b56052f44d Clean up doxygen syntax and reword comments to flow better, have a brief
section, and not have unfinished sentence fragments.

llvm-svn: 220147
2014-10-18 23:31:55 +00:00
Chandler Carruth d67244df4e Clean up the formatting and trailing whitespace of a routine before
editting it.

llvm-svn: 220146
2014-10-18 23:19:03 +00:00
Hal Finkel 2400c96cc3 [LVI] Add some additional comments about caching and context instructions
Philip Reames and I had a long conversation about this, mostly because it is
not obvious why the current logic is correct. Hopefully, these comments will
prevent such confusion in the future.

llvm-svn: 219882
2014-10-16 00:40:05 +00:00
Sanjoy Das 360b1ed5f2 Revert "r219834 - Teach ScalarEvolution to sharpen range information"
This change breaks the asan buildbots:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux/builds/13468

llvm-svn: 219878
2014-10-15 23:46:04 +00:00
Sanjoy Das 90c2f1455a Teach ScalarEvolution to sharpen range information.
If x is known to have the range [a, b) in a loop predicated by (icmp
ne x, a), its range can be sharpened to [a + 1, b).  Get
ScalarEvolution and hence IndVars to exploit this fact.
    
This change triggers an optimization to widen-loop-comp.ll, so it had
to be edited to get it to pass.

phabricator: http://reviews.llvm.org/D5639
llvm-svn: 219834
2014-10-15 19:25:28 +00:00
Hal Finkel 8683d2b0d2 Treat the WorkSet used to find ephemeral values as double-ended
We need to make sure that we visit all operands of an instruction before moving
deeper in the operand graph. We had been pushing operands onto the back of the work
set, and popping them off the back as well, meaning that we might visit an
instruction before visiting all of its uses that sit in between it and the call
to @llvm.assume.

To provide an explicit example, given the following:
  %q0 = extractelement <4 x float> %rd, i32 0
  %q1 = extractelement <4 x float> %rd, i32 1
  %q2 = extractelement <4 x float> %rd, i32 2
  %q3 = extractelement <4 x float> %rd, i32 3
  %q4 = fadd float %q0, %q1
  %q5 = fadd float %q2, %q3
  %q6 = fadd float %q4, %q5
  %qi = fcmp olt float %q6, %q5
  call void @llvm.assume(i1 %qi)

%q5 is used by both %qi and %q6. When we visit %qi, it will be marked as
ephemeral, and we'll queue %q6 and %q5. %q6 will be marked as ephemeral and
we'll queue %q4 and %q5. Under the old system, we'd then visit %q4, which
would become ephemeral, %q1 and then %q0, which would become ephemeral as
well, and now we have a problem. We'd visit %rd, but it would not be marked as
ephemeral because we've not yet visited %q2 and %q3 (because we've not yet
visited %q5).

This will be covered by a test case in a follow-up commit that enables
ephemeral-value awareness in the SLP vectorizer.

llvm-svn: 219815
2014-10-15 17:34:48 +00:00
Hal Finkel db5f86a9bf [CFL-AA] CFL-AA should not assert on an va_arg instruction
The CFL-AA implementation was missing a visit* routine for va_arg instructions,
causing it to assert when run on a function that had one. For now, handle these
in a conservative way.

Fixes PR20954.

llvm-svn: 219718
2014-10-14 20:51:26 +00:00
Hal Finkel a3f23e3725 [LVI] Check for @llvm.assume dominating the edge branch
When LazyValueInfo uses @llvm.assume intrinsics to provide edge-value
constraints, we should check for intrinsics that dominate the edge's branch,
not just any potential context instructions. An assumption that dominates the
edge's branch represents a truth on that edge. This is specifically useful, for
example, if multiple predecessors assume a pointer to be nonnull, allowing us
to simplify a later null comparison.

The test case, and an initial patch, were provided by Philip Reames. Thanks!

llvm-svn: 219688
2014-10-14 16:04:49 +00:00
Richard Smith dc69ce32ef [modules] Stop excluding Support/Debug.h from the Support module. This header
has been modular since r206822, and excluding it was leading to workarounds
such as the one in r219592, which this change removes.

llvm-svn: 219593
2014-10-13 00:41:03 +00:00
Benjamin Kramer 24165219b1 [Modules] Add some missing includes to make files compile stand-alone.
llvm-svn: 219592
2014-10-12 22:49:26 +00:00
Benjamin Kramer 603c2c79ed AssumptionTracker: Don't create temporary CallbackVHs.
Those are expensive to create in cold cache scenarios. NFC.

llvm-svn: 219575
2014-10-11 19:13:01 +00:00
David Majnemer cb9d596655 InstCombine, InstSimplify: (%X /s C1) /s C2 isn't always 0 when C1 * C2 overflow
consider:
C1 = INT_MIN
C2 = -1

C1 * C2 overflows without a doubt but consider the following:
%x = i32 INT_MIN

This means that (%X /s C1) is 1 and (%X /s C1) /s C2 is -1.

N. B.  Move the unsigned version of this transform to InstSimplify, it
doesn't create any new instructions.

This fixes PR21243.

llvm-svn: 219567
2014-10-11 10:20:01 +00:00
Chandler Carruth 6666c27e99 [SCEV] Add some asserts to the recently improved trip count computation
routines and fix all of the bugs they expose.

I hit a test case that crashed even without these asserts due to passing
a non-exiting latch to the ExitingBlock parameter of the trip count
computation machinery. However, when I add the nice asserts, it turns
out we have plenty of coverage of these bugs, they just didn't manifest
in crashers.

The core problem seems to stem from an assumption that the latch *is*
the exiting block. While this is often true, and somewhat the "normal"
way to think about loops, it isn't necessarily true. The correct way to
call the trip count routines in a *generic* fashion (that is, without
a particular exit in mind) is to just use the loop's single exiting
block if it has one. The trip count can't be computed generically unless
it does. This works great for the loop vectorizer. The loop unroller
actually *wants* to select the latch when it has to chose between
multiple exits because for unrolling it is the latch trips that matter.
But if this is the desire, it needs to explicitly guard for non-exiting
latches and check for the generic trip count in that case.

I've added the asserts, and added convenience APIs for querying the trip
count generically that check for a single exit block. I've kept the APIs
consistent between computing trip count and trip multiples.

Thansk to Mark for the help debugging and tracking down the *right* fix
here!

llvm-svn: 219550
2014-10-11 00:12:11 +00:00
Sanjoy Das 1f05c51e5e This patch teaches ScalarEvolution to pick and use !range metadata.
It also makes it more aggressive in querying range information by
adding a call to isKnownPredicateWithRanges to
isLoopBackedgeGuardedByCond and isLoopEntryGuardedByCond.

phabricator: http://reviews.llvm.org/D5638

Reviewed by: atrick, hfinkel

llvm-svn: 219532
2014-10-10 21:22:34 +00:00
Mark Heffernan 2beab5f0b4 This patch de-pessimizes the calculation of loop trip counts in
ScalarEvolution in the presence of multiple exits. Previously all
loops exits had to have identical counts for a loop trip count to be
considered computable. This pessimization was implemented by calling
getBackedgeTakenCount(L) rather than getExitCount(L, ExitingBlock)
inside of ScalarEvolution::getSmallConstantTripCount() (see the FIXME
in the comments of that function). The pessimization was added to fix
a corner case involving undefined behavior (pr/16130). This patch more
precisely handles the undefined behavior case allowing the pessimization
to be removed.

ControlsExit replaces IsSubExpr to more precisely track the case where
undefined behavior is expected to occur. Because undefined behavior is
tracked more precisely we can remove MustExit from ExitLimit. MustExit
was used to track the case where the limit was computed potentially
assuming undefined behavior even if undefined behavior didn't necessarily
occur.

llvm-svn: 219517
2014-10-10 17:39:11 +00:00
Hal Finkel 49dadc0bc3 [LVI] Revert the remainder of "r218231 - Add two thresholds lvi-overdefined-BB-threshold and lvi-overdefined-threshold"
Some of r218231 was reverted with the code that used it in r218971, but not all
of it. This removes the rest (which is now dead).

llvm-svn: 219469
2014-10-10 03:56:24 +00:00
Hal Finkel cbbd3df836 Revert "[BasicAA] Revert "Revert r218714 - Make better use of zext and sign information.""
This reverts commit r219135 -- still causing miscompiles in SPEC it seems...

llvm-svn: 219432
2014-10-09 19:48:12 +00:00
Hal Finkel 43ce71f1b1 [BasicAA] Revert "Revert r218714 - Make better use of zext and sign information."
This reverts r218944, which reverted r218714, plus a bug fix.

Description of the bug in r218714 (by Nick)

The original patch forgot to check if the Scale in VariableGEPIndex flipped the
sign of the variable. The BasicAA pass iterates over the instructions in the
order they appear in the function, and so BasicAliasAnalysis::aliasGEP is
called with the variable it first comes across as parameter GEP1. Adding a
%reorder label puts the definition of %a after %b so aliasGEP is called with %b
as the first parameter and %a as the second. aliasGEP later calculates that %a
== %b + 1 - %idxprom where %idxprom >= 0 (if %a was passed as the first
parameter it would calculate %b == %a - 1 + %idxprom where %idxprom >= 0) -
ignoring that %idxprom is scaled by -1 here lead the patch to incorrectly
conclude that %a > %b.

Revised patch by Nick White, thanks! Thanks to Lang to isolating the bug.
Slightly modified by me to add an early exit from the loop and avoid
unnecessary, but expensive, function calls.

Original commit message:

Two related things:

 1. Fixes a bug when calculating the offset in GetLinearExpression. The code
    previously used zext to extend the offset, so negative offsets were converted
    to large positive ones.

 2. Enhance aliasGEP to deduce that, if the difference between two GEP
    allocations is positive and all the variables that govern the offset are also
    positive (i.e. the offset is strictly after the higher base pointer), then
    locations that fit in the gap between the two base pointers are NoAlias.

Patch by Nick White!

llvm-svn: 219135
2014-10-06 18:37:59 +00:00
Duncan P. N. Exon Smith a7a90a2f19 BFI: Improve assertion message, since it's actually firing
This assertion is firing because -loop-unroll is failing to preserve
-loop-info (see PR20987).  Improve it.

llvm-svn: 219130
2014-10-06 17:42:00 +00:00
Hal Finkel 8eae3ad2ff [CFL-AA] Update for handling of globals and more tests
We used to return PartialAlias if *either* variable being queried interacted
with arguments or globals. AFAICT, we can change this to only returning
MayAlias iff *both* variables being queried interacted with arguments or
globals.

Also, adding some basic functionality tests: some basic IPA tests, checking
that we give conservative responses with arguments/globals thrown in the mix,
and ensuring that we trace values through stores and loads.

Note that saying that 'x' interacted with arguments or globals means that the
Attributes of the StratifiedSet that 'x' belongs to has any bits set.

Patch by George Burgess IV, thanks!

llvm-svn: 219122
2014-10-06 14:42:56 +00:00
Benjamin Kramer 12a2d10769 Simplify code. No functionality change.
llvm-svn: 219082
2014-10-05 12:21:57 +00:00
Benjamin Kramer 2e52f02864 Make AAMDNodes ctor and operator bool (!!!) explicit, mop up bugs and weirdness exposed by it.
llvm-svn: 219068
2014-10-04 22:44:29 +00:00
Richard Smith 1ed4229f6f PR21145: Teach LLVM about C++14 sized deallocation functions.
C++14 adds new builtin signatures for 'operator delete'. This change allows
new/delete pairs to be removed in C++14 onwards, as they were in C++11 and
before.

llvm-svn: 219014
2014-10-03 20:17:06 +00:00
James Molloy cb7449d058 Revert r215343.
This was contentious and needs invesigation.

llvm-svn: 218971
2014-10-03 09:29:24 +00:00
Lang Hames 89e9c17235 [BasicAA] Revert r218714 - Make better use of zext and sign information.
This patch broke 447.dealII on Darwin. I'm currently working on a reduced
test-case, but reverting for now to keep the bots happy.

<rdar://problem/18530107>

llvm-svn: 218944
2014-10-03 01:33:47 +00:00
Sanjay Patel 0d7dee654d Remove duplicate function names from comments. NFC.
llvm-svn: 218875
2014-10-02 15:13:22 +00:00
Aaron Ballman 254dd7e439 Silence a -Wsign-compare warning. NFC.
llvm-svn: 218868
2014-10-02 13:17:11 +00:00
Argyrios Kyrtzidis 0b9f5507c8 Adds 'override' to overriding methods. NFC.
llvm-svn: 218815
2014-10-01 21:00:44 +00:00
Sanjay Patel 7b2cd9ad86 Make the sqrt intrinsic return undef for a negative input.
As discussed here:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20140609/220598.html

And again here:
http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-September/077168.html

The sqrt of a negative number when using the llvm intrinsic is undefined. 
We should return undef rather than 0.0 to match the definition in the LLVM IR lang ref.

This change should not affect any code that isn't using "no-nans-fp-math"; 
ie, no-nans is a requirement for generating the llvm intrinsic in place of a sqrt function call.

Unfortunately, the behavior introduced by this patch will not match current gcc, xlc, icc, and 
possibly other compilers. The current clang/llvm behavior of returning 0.0 doesn't either. 
We knowingly approve of this difference with the other compilers in an attempt to flag code 
that is invoking undefined behavior.

A front-end warning should also try to convince the user that the program will fail:
http://llvm.org/bugs/show_bug.cgi?id=21093

Differential Revision: http://reviews.llvm.org/D5527

llvm-svn: 218803
2014-10-01 20:36:33 +00:00
Bruno Cardoso Lopes e3c513a965 [MemoryDepAnalysis] Fix compile time slowdown
- Problem
One program takes ~3min to compile under -O2. This happens after a certain
function A is inlined ~700 times in a function B, inserting thousands of new
BBs. This leads to 80% of the compilation time spent in
GVN::processNonLocalLoad and
MemoryDependenceAnalysis::getNonLocalPointerDependency, while searching for
nonlocal information for basic blocks.

Usually, to avoid spending a long time to process nonlocal loads, GVN bails out
if it gets more than 100 deps as a result from
MD->getNonLocalPointerDependency.  However this only happens *after* all
nonlocal information for BBs have been computed, which is the bottleneck in
this scenario. For instance, there are 8280 times where
getNonLocalPointerDependency returns deps with more than 100 bbs and from
those, 600 times it returns more than 1000 blocks.

- Solution
Bail out early during the nonlocal info computation whenever we reach a
specified threshold.  This patch proposes a 100 BBs threshold, it also
reduces the compile time from 3min to 23s.

- Testing
The test-suite presented no compile nor execution time regressions.

Some numbers from my machine (x86_64 darwin):
 - 17s under -Oz (which avoids inlining).
 - 1.3s under -O1.
 - 2m51s under -O2 ToT
 *** 23s under -O2 w/ Result.size() > 100
 - 1m54s under -O2 w/ Result.size() > 500

With NumResultsLimit = 100, GVN yields the same outcome as in the
unlimited 3min version.

http://reviews.llvm.org/D5532
rdar://problem/18188041

llvm-svn: 218792
2014-10-01 20:07:13 +00:00
Hal Finkel fd86317989 [BasicAA] Make better use of zext and sign information
Two related things:

 1. Fixes a bug when calculating the offset in GetLinearExpression. The code
    previously used zext to extend the offset, so negative offsets were converted
    to large positive ones.

 2. Enhance aliasGEP to deduce that, if the difference between two GEP
    allocations is positive and all the variables that govern the offset are also
    positive (i.e. the offset is strictly after the higher base pointer), then
    locations that fit in the gap between the two base pointers are NoAlias.

Patch by Nick White!

llvm-svn: 218714
2014-09-30 22:43:40 +00:00
David Peixotto 472b05b36c Ignore annotation function calls in cost computation
The annotation instructions are dropped during codegen and have no
impact on size.  In some cases, the annotations were preventing the
unroller from unrolling a loop because the annotation calls were
pushing the cost over the unrolling threshold.

Differential Revision: http://reviews.llvm.org/D5335

llvm-svn: 218525
2014-09-26 17:48:40 +00:00
David Peixotto 0d4d5e64ec Fix assertion in LICM doFinalization()
The doFinalization method checks that the LoopToAliasSetMap is
empty. LICM populates that map as it runs through the loop nest,
deleting the entries for child loops as it goes. However, if a child
loop is deleted by another pass (e.g. unrolling) then the loop will
never be deleted from the map because LICM walks the loop nest to
find entries it can delete.

The fix is to delete the loop from the map and free the alias set
when the loop is deleted from the loop nest.

Differential Revision: http://reviews.llvm.org/D5305

llvm-svn: 218387
2014-09-24 16:48:31 +00:00
Jiangning Liu cd1d79e77c Add two thresholds lvi-overdefined-BB-threshold and lvi-overdefined-threshold
for LVI algorithm. For a specific value to be lowered, when the number of basic
blocks being checked for overdefined lattice value is larger than
lvi-overdefined-BB-threshold, or the times of encountering overdefined value
for a single basic block is larger than lvi-overdefined-threshold, the LVI
algorithm will stop further lowering the lattice value.

llvm-svn: 218231
2014-09-22 02:23:05 +00:00
Eric Christopher d4838554ac Add file to CMake build as well.
llvm-svn: 218005
2014-09-18 00:39:20 +00:00
Eric Christopher d85ffb1fc0 Add a new pass FunctionTargetTransformInfo. This pass serves as a
shim between the TargetTransformInfo immutable pass and the Subtarget
via the TargetMachine and Function. Migrate a single call from
BasicTargetTransformInfo as an example and provide shims where TargetMachine
begins taking a Function to determine the subtarget.

No functional change.

llvm-svn: 218004
2014-09-18 00:34:14 +00:00
David Majnemer b435a4214e InstSimplify: Don't allow (x srem y) urem y -> x srem y
Let's consider the case where:
%x i16 = 32768
%y i16 = 384

%x srem %y = 65408
(%x srem %y) urem %y = 128

llvm-svn: 217939
2014-09-17 04:16:35 +00:00
David Majnemer ac717f0972 InstSimplify: ((X % Y) % Y) -> (X % Y)
Patch by Sonam Kumari!

Differential Revision: http://reviews.llvm.org/D5350

llvm-svn: 217937
2014-09-17 03:34:34 +00:00
David Majnemer a315bd80c2 InstSimplify: Simplify trivial and/or of icmps
Some ICmpInsts when anded/ored with another ICmpInst trivially reduces
to true or false depending on whether or not all integers or no integers
satisfy the intersected/unioned range.

This sort of trivial looking code can come about when InstCombine
performs a range reduction-type operation on sdiv and the like.

This fixes PR20916.

llvm-svn: 217750
2014-09-15 08:15:28 +00:00
Benjamin Kramer cfd8d90969 Fix an ODR violation consisting of two 'struct Query' in the global namespace.
Put them in their own anonymous namespaces. Found by GCC's new -Wodr (PR20915).

llvm-svn: 217662
2014-09-12 08:56:53 +00:00
Sanjay Patel b653de1ada Rename getMaximumUnrollFactor -> getMaxInterleaveFactor; also rename option names controlling this variable.
"Unroll" is not the appropriate name for this variable. Clang already uses 
the term "interleave" in pragmas and metadata for this.

Differential Revision: http://reviews.llvm.org/D5066

llvm-svn: 217528
2014-09-10 17:58:16 +00:00
Hal Finkel cebf0cc210 Make use @llvm.assume for loop guards in ScalarEvolution
This adds a basic (but important) use of @llvm.assume calls in ScalarEvolution.
When SE is attempting to validate a condition guarding a loop (such as whether
or not the loop count can be zero), this check should also include dominating
assumptions.

llvm-svn: 217348
2014-09-07 21:37:59 +00:00
Hal Finkel 7e1844940e Make use of @llvm.assume from LazyValueInfo
This change teaches LazyValueInfo to use the @llvm.assume intrinsic. Like with
the known-bits change (r217342), this requires feeding a "context" instruction
pointer through many functions. Aside from a little refactoring to reuse the
logic that turns predicates into constant ranges in LVI, the only new code is
that which can 'merge' the range from an assumption into that otherwise
computed. There is also a small addition to JumpThreading so that it can have
LVI use assumptions in the same block as the comparison feeding a conditional
branch.

With this patch, we can now simplify this as expected:
int foo(int a) {
  __builtin_assume(a > 5);
  if (a > 3) {
    bar();
    return 1;
  }
  return 0;
}

llvm-svn: 217345
2014-09-07 20:29:59 +00:00
Hal Finkel 15aeaaf24a Add additional patterns for @llvm.assume in ValueTracking
This builds on r217342, which added the infrastructure to compute known bits
using assumptions (@llvm.assume calls). That original commit added only a few
patterns (to catch common cases related to determining pointer alignment); this
change adds several other patterns for simple cases.

r217342 contained that, for assume(v & b = a), bits in the mask
that are known to be one, we can propagate known bits from the a to v. It also
had a known-bits transfer for assume(a = b). This patch adds:

assume(~(v & b) = a) : For those bits in the mask that are known to be one, we
                       can propagate inverted known bits from the a to v.

assume(v | b = a) :    For those bits in b that are known to be zero, we can
                       propagate known bits from the a to v.

assume(~(v | b) = a):  For those bits in b that are known to be zero, we can
                       propagate inverted known bits from the a to v.

assume(v ^ b = a) :    For those bits in b that are known to be zero, we can
		       propagate known bits from the a to v. For those bits in
		       b that are known to be one, we can propagate inverted
                       known bits from the a to v.

assume(~(v ^ b) = a) : For those bits in b that are known to be zero, we can
		       propagate inverted known bits from the a to v. For those
		       bits in b that are known to be one, we can propagate
                       known bits from the a to v.

assume(v << c = a) :   For those bits in a that are known, we can propagate them
                       to known bits in v shifted to the right by c.

assume(~(v << c) = a) : For those bits in a that are known, we can propagate
                        them inverted to known bits in v shifted to the right by c.

assume(v >> c = a) :   For those bits in a that are known, we can propagate them
                       to known bits in v shifted to the right by c.

assume(~(v >> c) = a) : For those bits in a that are known, we can propagate
                        them inverted to known bits in v shifted to the right by c.

assume(v >=_s c) where c is non-negative: The sign bit of v is zero

assume(v >_s c) where c is at least -1: The sign bit of v is zero

assume(v <=_s c) where c is negative: The sign bit of v is one

assume(v <_s c) where c is non-positive: The sign bit of v is one

assume(v <=_u c): Transfer the known high zero bits

assume(v <_u c): Transfer the known high zero bits (if c is know to be a power
                 of 2, transfer one more)

A small addition to InstCombine was necessary for some of the test cases. The
problem is that when InstCombine was simplifying and, or, etc. it would fail to
check the 'do I know all of the bits' condition before checking less specific
conditions and would not fully constant-fold the result. I'm not sure how to
trigger this aside from using assumptions, so I've just included the change
here.

llvm-svn: 217343
2014-09-07 19:21:07 +00:00
Hal Finkel 60db05896a Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.)
This change, which allows @llvm.assume to be used from within computeKnownBits
(and other associated functions in ValueTracking), adds some (optional)
parameters to computeKnownBits and friends. These functions now (optionally)
take a "context" instruction pointer, an AssumptionTracker pointer, and also a
DomTree pointer, and most of the changes are just to pass this new information
when it is easily available from InstSimplify, InstCombine, etc.

As explained below, the significant conceptual change is that known properties
of a value might depend on the control-flow location of the use (because we
care that the @llvm.assume dominates the use because assumptions have
control-flow dependencies). This means that, when we ask if bits are known in a
value, we might get different answers for different uses.

The significant changes are all in ValueTracking. Two main changes: First, as
with the rest of the code, new parameters need to be passed around. To make
this easier, I grouped them into a structure, and I made internal static
versions of the relevant functions that take this structure as a parameter. The
new code does as you might expect, it looks for @llvm.assume calls that make
use of the value we're trying to learn something about (often indirectly),
attempts to pattern match that expression, and uses the result if successful.
By making use of the AssumptionTracker, the process of finding @llvm.assume
calls is not expensive.

Part of the structure being passed around inside ValueTracking is a set of
already-considered @llvm.assume calls. This is to prevent a query using, for
example, the assume(a == b), to recurse on itself. The context and DT params
are used to find applicable assumptions. An assumption needs to dominate the
context instruction, or come after it deterministically. In this latter case we
only handle the specific case where both the assumption and the context
instruction are in the same block, and we need to exclude assumptions from
being used to simplify their own ephemeral values (those which contribute only
to the assumption) because otherwise the assumption would prove its feeding
comparison trivial and would be removed.

This commit adds the plumbing and the logic for a simple masked-bit propagation
(just enough to write a regression test). Future commits add more patterns
(and, correspondingly, more regression tests).

llvm-svn: 217342
2014-09-07 18:57:58 +00:00
Hal Finkel 57f03dda49 Add functions for finding ephemeral values
This adds a set of utility functions for collecting 'ephemeral' values. These
are LLVM IR values that are used only by @llvm.assume intrinsics (directly or
indirectly), and thus will be removed prior to code generation, implying that
they should be considered free for certain purposes (like inlining). The
inliner's cost analysis, and a few other passes, have been updated to account
for ephemeral values using the provided functionality.

This functionality is important for the usability of @llvm.assume, because it
limits the "non-local" side-effects of adding llvm.assume on inlining, loop
unrolling, etc. (these are hints, and do not generate code, so they should not
directly contribute to estimates of execution cost).

llvm-svn: 217335
2014-09-07 13:49:57 +00:00
Hal Finkel 74c2f355d2 Add an Assumption-Tracking Pass
This adds an immutable pass, AssumptionTracker, which keeps a cache of
@llvm.assume call instructions within a module. It uses callback value handles
to keep stale functions and intrinsics out of the map, and it relies on any
code that creates new @llvm.assume calls to notify it of the new instructions.
The benefit is that code needing to find @llvm.assume intrinsics can do so
directly, without scanning the function, thus allowing the cost of @llvm.assume
handling to be negligible when none are present.

The current design is intended to be lightweight. We don't keep track of
anything until we need a list of assumptions in some function. The first time
this happens, we scan the function. After that, we add/remove @llvm.assume
calls from the cache in response to registration calls and ValueHandle
callbacks.

There are no new direct test cases for this pass, but because it calls it
validation function upon module finalization, we'll pick up detectable
inconsistencies from the other tests that touch @llvm.assume calls.

This pass will be used by follow-up commits that make use of @llvm.assume.

llvm-svn: 217334
2014-09-07 12:44:26 +00:00
Benjamin Kramer 8c90fd71f7 Add override to overriden virtual methods, remove virtual keywords.
No functionality change. Changes made by clang-tidy + some manual cleanup.

llvm-svn: 217028
2014-09-03 11:41:21 +00:00
Hal Finkel 85f2692d2f [CFLAA] Remove one final initializer list
Maybe MSVC will be happy now...

llvm-svn: 217000
2014-09-03 00:06:47 +00:00
Hal Finkel 1ae325f53d [CFLAA] And even more MSVC fixes
Remove a couple more initializer lists and constexpr dependencies.

llvm-svn: 216998
2014-09-02 23:50:01 +00:00
Hal Finkel ca616acd73 [CFLAA] More cleanup for MSVC
Remove more initializer lists, etc.

llvm-svn: 216994
2014-09-02 23:29:48 +00:00
Hal Finkel 8d1590dc4b [CFLAA] No initializer lists for MSVC
MSVC 2012 does not understand initializer lists; remove them.

llvm-svn: 216991
2014-09-02 22:52:30 +00:00
Hal Finkel 42b7e01f7c [CFLAA] Remove tautological comparison
Fixes this (the warning is right, the unsigned value is not negative):
lib/Analysis/StratifiedSets.h:689:53: warning: comparison of unsigned expression >= 0 is always true [-Wtautological-compare]
  bool inbounds(StratifiedIndex N) const { return N >= 0 && N < Links.size(); }

llvm-svn: 216987
2014-09-02 22:36:58 +00:00
Hal Finkel 981602a84c [CFLAA] LLVM_CONSTEXPR -> const
The number is just a constant, and this should make MSVC happy (or at least
happier).

llvm-svn: 216981
2014-09-02 22:26:06 +00:00
Hal Finkel 7d7087c124 [CFLAA] constexpr -> LLVM_CONSTEXPR
Attempt to fix the MSVC build by not using constexpr.

llvm-svn: 216979
2014-09-02 22:13:00 +00:00
Hal Finkel 7529c55c02 Add a CFL Alias Analysis implementation
This provides an implementation of CFL alias analysis (including some
supporting data structures). Currently, we don't have any extremely fancy
features, sans some interprocedural analysis (i.e. no field sensitivity, etc.),
and we do best sitting behind BasicAA + TBAA. In such a configuration, we take
~0.6-0.8% of total compile time, and give ~7-8% NoAlias responses to queries
TBAA and BasicAA couldn't answer when bootstrapping LLVM. In testing this on
other projects, we've seen up to 10.5% of queries dropped by BasicAA+TBAA
answered with NoAlias by this algorithm.

Patch by George Burgess IV (with minor modifications by me -- mostly adapting
some BasicAA tests), thanks!

llvm-svn: 216970
2014-09-02 21:43:13 +00:00
Robin Morisset 4f6b93b1a8 Fix MemoryDependenceAnalysis in cases where QueryInstr is a CmpXchg or a AtomicRMW
Summary:
MemoryDependenceAnalysis is currently cautious when the QueryInstr is an atomic
load or store, but I forgot to check for atomic cmpxchg/atomicrmw. This patch
is a way of fixing that, and making it less brittle (i.e. no risk that I forget
another possible kind of atomic, even if the IR ends up changing in the future),
by adding a fallback checking mayReadOrWriteFromMemory.

Thanks to Philip Reames for finding this bug and suggesting this solution in
http://reviews.llvm.org/D4845

Sadly, I don't see how to add a test for this, since the passes depending on
MemoryDependenceAnalysis won't trigger for an atomic rmw anyway. Does anyone
see a way for testing it?

Test Plan: none possible at first sight

Reviewers: jfb, reames

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5019

llvm-svn: 216940
2014-09-02 20:17:52 +00:00
Nick Lewycky 97756409ea Remove an errant outer loop that contains nothing but an inner loop over exactly the same elements. While no functionality is change intended (and hence there are no changes to tests), you don't want to skip this revision if bisecting for errors.
llvm-svn: 216864
2014-09-01 05:17:15 +00:00
Craig Topper fd38cbebda Remove 'virtual' keyword from methods markedwith 'override' keyword.
llvm-svn: 216823
2014-08-30 16:48:34 +00:00
Robin Morisset 039781ef26 Fix typos in comments, NFC
Summary: Just fixing comments, no functional change.

Test Plan: N/A

Reviewers: jfb

Subscribers: mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D5130

llvm-svn: 216784
2014-08-29 21:53:01 +00:00
Robin Morisset 163ef0402a Relax the constraint more in MemoryDependencyAnalysis.cpp
Even loads/stores that have a stronger ordering than monotonic can be safe.
The rule is no release-acquire pair on the path from the QueryInst, assuming that
the QueryInst is not atomic itself.

llvm-svn: 216771
2014-08-29 20:32:58 +00:00
Matt Arsenault 85cbc7e371 Make fabs safe to speculatively execute
llvm-svn: 216736
2014-08-29 16:01:17 +00:00
David Majnemer 76d06bc613 InstSimplify: Move a transform from InstCombine to InstSimplify
Several combines involving icmp (shl C2, %X) C1 can be simplified
without introducing any new instructions.  Move them to InstSimplify;
while we are at it, make them more powerful.

llvm-svn: 216642
2014-08-28 03:34:28 +00:00
David Majnemer 11ca2971e8 InstSimplify: Don't simplify gep X, (Y-X) to Y if types differ
It's incorrect to perform this simplification if the types differ.
A bitcast would need to be inserted for this to work.

This fixes PR20771.

llvm-svn: 216597
2014-08-27 20:08:34 +00:00
Nico Weber 48c82400ed Reland r216439 215441, majnemer has a real fix for PR20771.
llvm-svn: 216586
2014-08-27 20:06:19 +00:00
Nico Weber 7b343e3cc6 Revert r216439 (and r216441, else the former doesn't revert cleanly).
It caused PR 20771. I'll land a test on the clang side.

llvm-svn: 216582
2014-08-27 20:00:13 +00:00
David Majnemer d6d1671c1e InstSimplify: Compute comparison ranges for left shift instructions
'shl nuw CI, x' produces [CI, CI << CLZ(CI)]
'shl nsw CI, x' produces [CI << CLO(CI)-1, CI] if CI is negative
'shl nsw CI, x' produces [CI, CI << CLZ(CI)-1] if CI is non-negative

llvm-svn: 216570
2014-08-27 18:03:46 +00:00
David Majnemer 788d0ab8c8 InstSimplify: Fold gep X, (sub 0, ptrtoint(X)) to null
Save InstCombine some work if we can perform this fold during
InstSimplify.

llvm-svn: 216441
2014-08-26 07:08:03 +00:00
David Majnemer bc4981323f InstSimplify: Simplify trivial pointer expressions like b + (e - b)
consider:
long long *f(long long *b, long long *e) {
  return b + (e - b);
}

we would lower this to something like:
define i64* @f(i64* %b, i64* %e) {
  %1 = ptrtoint i64* %e to i64
  %2 = ptrtoint i64* %b to i64
  %3 = sub i64 %1, %2
  %4 = ashr exact i64 %3, 3
  %5 = getelementptr inbounds i64* %b, i64 %4
  ret i64* %5
}

This should fold away to just 'e'.

N.B.  This adds m_SpecificInt as a convenient way to match against a
particular 64-bit integer when using LLVM's match interface.

llvm-svn: 216439
2014-08-26 05:55:16 +00:00
Dylan Noblesmith 43f49cad78 Analysis: cleanup
Address review comments.

llvm-svn: 216432
2014-08-26 02:03:40 +00:00
Dylan Noblesmith 4ffafefdaa Revert "Analysis: unique_ptr-ify DependenceAnalysis::collectCoeffInfo"
This reverts commit r216358.

llvm-svn: 216431
2014-08-26 02:03:38 +00:00
Rafael Espindola 3fd1e9933f Modernize raw_fd_ostream's constructor a bit.
Take a StringRef instead of a "const char *".
Take a "std::error_code &" instead of a "std::string &" for error.

A create static method would be even better, but this patch is already a bit too
big.

llvm-svn: 216393
2014-08-25 18:16:47 +00:00
Karthik Bhat 7f33ff7dea Allow vectorization of division by uniform power of 2.
This patch adds support to recognize division by uniform power of 2 and modifies the cost table to vectorize division by uniform power of 2 whenever possible.
Updates Cost model for Loop and SLP Vectorizer.The cost table is currently only updated for X86 backend.
Thanks to Hal, Andrea, Sanjay for the review. (http://reviews.llvm.org/D4971)

llvm-svn: 216371
2014-08-25 04:56:54 +00:00
Dylan Noblesmith 3ecd22fcf5 Analysis: unique_ptr-ify DependenceAnalysis::collectCoeffInfo
llvm-svn: 216358
2014-08-25 00:28:43 +00:00
Dylan Noblesmith 2cae60e730 Analysis: unique_ptr-ify DependenceAnalysis::depends
llvm-svn: 216357
2014-08-25 00:28:39 +00:00
Dylan Noblesmith d96ce66cb1 Analysis: take a reference instead of pointer
This parameter is never null.

llvm-svn: 216356
2014-08-25 00:28:35 +00:00
Craig Topper 4627679cec Use range based for loops to avoid needing to re-mention SmallPtrSet size.
llvm-svn: 216351
2014-08-24 23:23:06 +00:00
David Majnemer 97ddca3224 ValueTracking: Figure out more bits when looking at add/sub
Given something like X01XX + X01XX, we know that the result must look
like X1XXX.

Adapted from a patch by Richard Smith, test-case written by me.

llvm-svn: 216250
2014-08-22 00:40:43 +00:00
Craig Topper 71b7b68b74 Repace SmallPtrSet with SmallPtrSetImpl in function arguments to avoid needing to mention the size.
llvm-svn: 216158
2014-08-21 05:55:13 +00:00
Robin Morisset 9e98e7f7fc Answer to Philip Reames comments
- add check for volatile (probably unneeded, but I agree that we should be conservative about it).
- strengthen condition from isUnordered() to isSimple(), as I don't understand well enough Unordered semantics (and it also matches the comment better this way) to be confident in the previous behaviour (thanks for catching that one, I had missed the case Monotonic/Unordered).
- separate a condition in two.
- lengthen comment about aliasing and loads
- add tests in GVN/atomic.ll

llvm-svn: 215943
2014-08-18 22:18:14 +00:00
Robin Morisset 4ffe8aaa69 Weak relaxing of the constraints on atomics in MemoryDependencyAnalysis
Monotonic accesses do not have to kill the analysis, as long as the QueryInstr is not
itself atomic.

llvm-svn: 215942
2014-08-18 22:18:11 +00:00
Craig Topper 6230691c91 Revert "Repace SmallPtrSet with SmallPtrSetImpl in function arguments to avoid needing to mention the size."
Getting a weird buildbot failure that I need to investigate.

llvm-svn: 215870
2014-08-18 00:24:38 +00:00
Craig Topper 5229cfd163 Repace SmallPtrSet with SmallPtrSetImpl in function arguments to avoid needing to mention the size.
llvm-svn: 215868
2014-08-17 23:47:00 +00:00
Jiangning Liu 40b04fd994 In LVI(Lazy Value Info), originally value on a BB can only be caculated once,
and the lattice will be updated to be a state other than "undefined". This
limiation could miss some opportunities of lowering "overdefined" to be an
even accurate value. So this patch ask the algorithm to try to lower the
lattice value again even if the value has been lowered to be "overdefined".

llvm-svn: 215343
2014-08-11 05:02:04 +00:00
Richard Smith 56579b6324 Remove Support/IncludeFile.h and its only user. This is actively harmful, since
it breaks the modules builds (where CallGraph.h can be quite reasonably
transitively included by an unimported portion of a module, and CallGraph.cpp
not linked in), and appears to have been entirely redundant since PR780 was
fixed back in 2008.

If this breaks anything, please revert; I have only tested this with a single
configuration, and it's possible that this is still somehow fixing something
(though I doubt it, since no other similar file uses this mechanism any more).

llvm-svn: 215142
2014-08-07 20:41:17 +00:00
James Molloy 2b8933c354 Teach the SLP Vectorizer that keeping some values live over a callsite can have a cost.
Some types, such as 128-bit vector types on AArch64, don't have any callee-saved registers. So if a value needs to stay live over a callsite, it must be spilled and refilled. This cost is now taken into account.

llvm-svn: 214859
2014-08-05 12:30:34 +00:00
Hal Finkel 36eff0f854 Fix ScalarEvolutionExpander when creating a PHI in a block with duplicate predecessors
It seems that when I fixed this, almost exactly a year ago, I did not quite do
it correctly. When we have duplicate block predecessors, we can indeed not have
different incoming values for the same block, but we *must* have duplicate
entries. So, instead of skipping the duplicates, we explicitly add the
duplicate incoming values.

Fixes PR20442.

llvm-svn: 214423
2014-07-31 19:13:38 +00:00
David Majnemer cd4fbcd1bb InstSimplify: Simplify (X - (0 - Y)) if the second sub is NUW
If the NUW bit is set for 0 - Y, we know that all values for Y other
than 0 would produce a poison value.  This allows us to replace (0 - Y)
with 0 in the expression (X - (0 - Y)) which will ultimately leave us
with X.

This partially fixes PR20189.

llvm-svn: 214384
2014-07-31 04:49:18 +00:00
Hal Finkel 930469107d Add @llvm.assume, lowering, and some basic properties
This is the first commit in a series that add an @llvm.assume intrinsic which
can be used to provide the optimizer with a condition it may assume to be true
(when the control flow would hit the intrinsic call). Some basic properties are added here:

 - llvm.invariant(true) is dead.
 - llvm.invariant(false) is unreachable (this directly corresponds to the
   documented behavior of MSVC's __assume(0)), so is llvm.invariant(undef).

The intrinsic is tagged as writing arbitrarily, in order to maintain control
dependencies. BasicAA has been updated, however, to return NoModRef for any
particular location-based query so that we don't unnecessarily block code
motion.

llvm-svn: 213973
2014-07-25 21:13:35 +00:00
Hal Finkel 029cde639c Simplify and improve scoped-noalias metadata semantics
In the process of fixing the noalias parameter -> metadata conversion process
that will take place during inlining (which will be committed soon, but not
turned on by default), I have come to realize that the semantics provided by
yesterday's commit are not really what we want. Here's why:

void foo(noalias a, noalias b, noalias c, bool x) {
  *q = x ? a : b;
  *c = *q;
}

Generically, we know that *c does not alias with *a and with *b (so there is an
'and' in what we know we're not), and we know that *q might be derived from *a
or from *b (so there is an 'or' in what we know that we are). So we do not want
the semantics currently, where any noalias scope matching any alias.scope
causes a NoAlias return. What we want to know is that the noalias scopes form a
superset of the alias.scope list (meaning that all the things we know we're not
is a superset of all of things the other instruction might be).

Making that change, however, introduces a composibility problem. If we inline
once, adding the noalias metadata, and then inline again adding more, and we
append new scopes onto the noalias and alias.scope lists each time. But, this
means that we could change what was a NoAlias result previously into a MayAlias
result because we appended an additional scope onto one of the alias.scope
lists. So, instead of giving scopes the ability to have parents (which I had
borrowed from the TBAA implementation, but seems increasingly unlikely to be
useful in practice), I've given them domains. The subset/superset condition now
applies within each domain independently, and we only need it to hold in one
domain. Each time we inline, we add the new scopes in a new scope domain, and
everything now composes nicely. In addition, this simplifies the
implementation.

llvm-svn: 213948
2014-07-25 15:50:02 +00:00
Hal Finkel 9414665a3b Add scoped-noalias metadata
This commit adds scoped noalias metadata. The primary motivations for this
feature are:
  1. To preserve noalias function attribute information when inlining
  2. To provide the ability to model block-scope C99 restrict pointers

Neither of these two abilities are added here, only the necessary
infrastructure. In fact, there should be no change to existing functionality,
only the addition of new features. The logic that converts noalias function
parameters into this metadata during inlining will come in a follow-up commit.

What is added here is the ability to generally specify noalias memory-access
sets. Regarding the metadata, alias-analysis scopes are defined similar to TBAA
nodes:

!scope0 = metadata !{ metadata !"scope of foo()" }
!scope1 = metadata !{ metadata !"scope 1", metadata !scope0 }
!scope2 = metadata !{ metadata !"scope 2", metadata !scope0 }
!scope3 = metadata !{ metadata !"scope 2.1", metadata !scope2 }
!scope4 = metadata !{ metadata !"scope 2.2", metadata !scope2 }

Loads and stores can be tagged with an alias-analysis scope, and also, with a
noalias tag for a specific scope:

... = load %ptr1, !alias.scope !{ !scope1 }
... = load %ptr2, !alias.scope !{ !scope1, !scope2 }, !noalias !{ !scope1 }

When evaluating an aliasing query, if one of the instructions is associated
with an alias.scope id that is identical to the noalias scope associated with
the other instruction, or is a descendant (in the scope hierarchy) of the
noalias scope associated with the other instruction, then the two memory
accesses are assumed not to alias.

Note that is the first element of the scope metadata is a string, then it can
be combined accross functions and translation units. The string can be replaced
by a self-reference to create globally unqiue scope identifiers.

[Note: This overview is slightly stylized, since the metadata nodes really need
to just be numbers (!0 instead of !scope0), and the scope lists are also global
unnamed metadata.]

Existing noalias metadata in a callee is "cloned" for use by the inlined code.
This is necessary because the aliasing scopes are unique to each call site
(because of possible control dependencies on the aliasing properties). For
example, consider a function: foo(noalias a, noalias b) { *a = *b; } that gets
inlined into bar() { ... if (...) foo(a1, b1); ... if (...) foo(a2, b2); } --
now just because we know that a1 does not alias with b1 at the first call site,
and a2 does not alias with b2 at the second call site, we cannot let inlining
these functons have the metadata imply that a1 does not alias with b2.

llvm-svn: 213864
2014-07-24 14:25:39 +00:00
Hal Finkel cc39b67530 AA metadata refactoring (introduce AAMDNodes)
In order to enable the preservation of noalias function parameter information
after inlining, and the representation of block-level __restrict__ pointer
information (etc.), additional kinds of aliasing metadata will be introduced.
This metadata needs to be carried around in AliasAnalysis::Location objects
(and MMOs at the SDAG level), and so we need to generalize the current scheme
(which is hard-coded to just one TBAA MDNode*).

This commit introduces only the necessary refactoring to allow for the
introduction of other aliasing metadata types, but does not actually introduce
any (that will come in a follow-up commit). What it does introduce is a new
AAMDNodes structure to hold all of the aliasing metadata nodes associated with
a particular memory-accessing instruction, and uses that structure instead of
the raw MDNode* in AliasAnalysis::Location, etc.

No functionality change intended.

llvm-svn: 213859
2014-07-24 12:16:19 +00:00
Hal Finkel ccc7090671 Make use of the align parameter attribute for all pointer arguments
We previously supported the align attribute on all (pointer) parameters, but we
only used it for byval parameters. However, it is completely consistent at the
IR level to treat 'align n' on all pointer parameters as an alignment
assumption on the pointer, and now we wll. Specifically, this causes
computeKnownBits to use the align attribute on all pointer parameters, not just
byval parameters. I've also added an explicit parameter attribute test for this
to test/Bitcode/attributes.ll.

And I've updated the LangRef to document the align parameter attribute (as it
turns out, it was not documented at all previously, although the byval
documentation mentioned that it could be used).

There are (at least) two benefits to doing this:
 - It allows enhancing alignment based on the pointer alignment after inlining callees.
 - It allows simplification of pointer arithmetic.

llvm-svn: 213670
2014-07-22 16:58:55 +00:00
Hal Finkel d32803b669 Match semantics of PointerMayBeCapturedBefore to its name by default
As it turns out, the capture tracker named CaptureBefore used by AA, and now
available via the PointerMayBeCapturedBefore function, would have been
more-aptly named CapturedBeforeOrAt, because it considers captures at the
instruction provided. This is not always what one wants, and it is difficult to
get the strictly-before behavior given only the current interface. This adds an
additional parameter which controls whether or not you want to include
captures at the provided instruction. The default is not to include the
instruction provided, so that 'Before' matches its name.

No functionality change intended.

llvm-svn: 213582
2014-07-21 21:30:22 +00:00
Duncan P. N. Exon Smith 6c99015fe2 Revert "[C++11] Add predecessors(BasicBlock *) / successors(BasicBlock *) iterator ranges."
This reverts commit r213474 (and r213475), which causes a miscompile on
a stage2 LTO build.  I'll reply on the list in a moment.

llvm-svn: 213562
2014-07-21 17:06:51 +00:00
Hal Finkel b035621720 Move the CapturesBefore tracker from AA into CaptureTracking
There were two generally-useful CaptureTracker classes defined in LLVM: the
simple tracker defined in CaptureTracking (and made available via the
PointerMayBeCaptured utility function), and the CapturesBefore tracker
available only inside of AA. This change moves the CapturesBefore tracker into
CaptureTracking, generalizes it slightly (by adding a ReturnCaptures
parameter), and makes it generally available via a PointerMayBeCapturedBefore
utility function.

This logic will be needed, for example, to perform noalias function parameter
attribute inference.

No functionality change intended.

llvm-svn: 213519
2014-07-21 13:15:48 +00:00
Hal Finkel c782aa5a9b Move isIdentifiedFunctionLocal from BasicAA to AA
The ability to identify function locals will exist outside of BasicAA (for
example, logic for inferring noalias function arguments will need this), so
make this concept generally accessible without code duplication.

No functionality change.

llvm-svn: 213514
2014-07-21 12:27:23 +00:00
Manuel Jacob 6d5cc8d656 Remove braces around single-statement block and rangify outer loop.
This is a follow-up to r213474.

llvm-svn: 213475
2014-07-20 09:20:47 +00:00
Manuel Jacob d11beffef4 [C++11] Add predecessors(BasicBlock *) / successors(BasicBlock *) iterator ranges.
Summary: This patch introduces two new iterator ranges and updates existing code to use it.  No functional change intended.

Test Plan: All tests (make check-all) still pass.

Reviewers: dblaikie

Reviewed By: dblaikie

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D4481

llvm-svn: 213474
2014-07-20 09:10:11 +00:00
NAKAMURA Takumi 8eb82fc453 Fix msc17 build. RegionInfo::RegionInfo::recalculate() doesn't make sense.
llvm-svn: 213466
2014-07-20 03:57:51 +00:00
NAKAMURA Takumi 118b0c789d Fix -Asserts build introduced since r213456.
llvm-svn: 213465
2014-07-20 00:00:42 +00:00
Matt Arsenault 1b8d83796d Templatify RegionInfo so it works on MachineBasicBlocks
llvm-svn: 213456
2014-07-19 18:29:29 +00:00
David Blaikie b61064ed39 Remove uses of the redundant ".reset(nullptr)" of unique_ptr, in favor of ".reset()"
It's also possible to just write "= nullptr", but there's some question
of whether that's as readable, so I leave it up to authors to pick which
they prefer for now. If we want to discuss standardizing on one or the
other, we can do that at some point in the future.

llvm-svn: 213438
2014-07-19 01:05:11 +00:00
Hal Finkel b0407ba071 Add a dereferenceable attribute
This attribute indicates that the parameter or return pointer is
dereferenceable. Practically speaking, loads from such a pointer within the
associated byte range are safe to speculatively execute. Such pointer
parameters are common in source languages (C++ references, for example).

llvm-svn: 213385
2014-07-18 15:51:28 +00:00
Suyog Sarda 1a212203bc Rectify r213231. Use proper version of 'ComputeNumSignBits'.
Earlier when the code was in InstCombine, we were calling the version of ComputeNumSignBits in InstCombine.h
that automatically added the DataLayout* before calling into ValueTracking.
When the code moved to InstSimplify, we are calling into ValueTracking directly without passing in the DataLayout*.
This patch rectifies the same by passing DataLayout in ComputeNumSignBits.

llvm-svn: 213295
2014-07-17 19:07:00 +00:00
Suyog Sarda 68862414b5 Move ashr optimization from InstCombineShift to InstSimplify.
Refactor code, no functionality change, test case moved from instcombine to instsimplify.

Differential Revision: http://reviews.llvm.org/D4102
 

llvm-svn: 213231
2014-07-17 06:28:15 +00:00
Hal Finkel 354e23b029 Improve BasicAA CS-CS queries (redux)
This reverts, "r213024 - Revert r212572 "improve BasicAA CS-CS queries", it
causes PR20303." with a fix for the bug in pr20303. As it turned out, the
relevant code was both wrong and over-conservative (because, as with the code
it replaced, it would return the overall ModRef mask even if just Ref had been
implied by the argument aliasing results). Hopefully, this correctly fixes both
problems.

Thanks to Nick Lewycky for reducing the test case for pr20303 (which I've
cleaned up a little and added in DSE's test directory). The BasicAA test has
also been updated to check for this error.

Original commit message:

BasicAA contains knowledge of certain intrinsics, such as memcpy and memset,
and uses that information to form more-accurate answers to CallSite vs. Loc
ModRef queries. Unfortunately, it did not use this information when answering
CallSite vs. CallSite queries.

Generically, when an intrinsic takes one or more pointers and the intrinsic is
marked only to read/write from its arguments, the offset/size is unknown. As a
result, the generic code that answers CallSite vs. CallSite (and CallSite vs.
Loc) queries in AA uses UnknownSize when forming Locs from an intrinsic's
arguments. While BasicAA's CallSite vs. Loc override could use more-accurate
size information for some intrinsics, it did not do the same for CallSite vs.
CallSite queries.

This change refactors the intrinsic-specific logic in BasicAA into a generic AA
query function: getArgLocation, which is overridden by BasicAA to supply the
intrinsic-specific knowledge, and used by AA's generic implementation. This
allows the intrinsic-specific knowledge to be used by both CallSite vs. Loc and
CallSite vs. CallSite queries, and simplifies the BasicAA implementation.

Currently, only one function, Mac's memset_pattern16, is handled by BasicAA
(all the rest are intrinsics). As a side-effect of this refactoring, BasicAA's
getModRefBehavior override now also returns OnlyAccessesArgumentPointees for
this function (which is an improvement).

llvm-svn: 213219
2014-07-17 01:28:25 +00:00
Matt Arsenault f1a7e62033 Teach computeKnownBits to look through addrspacecast.
This fixes inferring alignment through an addrspacecast.

llvm-svn: 213030
2014-07-15 01:55:03 +00:00
Matt Arsenault 70f4db88d5 Teach GetUnderlyingObject / BasicAA about addrspacecast
llvm-svn: 213025
2014-07-15 00:56:40 +00:00
Nick Lewycky 7a63c3b389 Revert r212572 "improve BasicAA CS-CS queries", it causes PR20303.
llvm-svn: 213024
2014-07-15 00:53:38 +00:00
Matt Arsenault caa9c71f32 Look through addrspacecast in IsConstantOffsetFromGlobal
llvm-svn: 213000
2014-07-14 22:39:26 +00:00
Matt Arsenault fd78d0c934 Look through addrspacecast in GetPointerBaseWithConstantOffset
llvm-svn: 212999
2014-07-14 22:39:22 +00:00
David Majnemer af9180fd04 InstSimplify: Correct sdiv x / -1
Determining the bounds of x/ -1 would start off with us dividing it by
INT_MIN.  Suffice to say, this would not work very well.

Instead, handle it upfront by checking for -1 and mapping it to the
range: [INT_MIN + 1, INT_MAX.  This means that the result of our
division can be any value other than INT_MIN.

llvm-svn: 212981
2014-07-14 20:38:45 +00:00
David Majnemer 5ea4fc0b33 InstSimplify: The upper bound of X / C was missing a rounding step
Summary:
When calculating the upper bound of X / -8589934592, we would perform
the following calculation: Floor[INT_MAX / 8589934592]

However, flooring the result would make us wrongly come to the
conclusion that 1073741824 was not in the set of possible values.
Instead, use the ceiling of the result.

Reviewers: nicholas

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D4502

llvm-svn: 212976
2014-07-14 19:49:57 +00:00
Matt Arsenault 4181ea36a9 Templatify DominanceFrontier.
Theoretically this should now work for MachineBasicBlocks.

llvm-svn: 212885
2014-07-12 21:59:52 +00:00
Duncan P. N. Exon Smith 6075510839 BFI: Add constructor for Weight
llvm-svn: 212868
2014-07-12 00:26:00 +00:00
Duncan P. N. Exon Smith 345c287da9 BFI: Clean up BlockMass
Implementation is small now -- the interesting logic was moved to
`BranchProbability` a while ago.  Move it into `bfi_detail` and get rid
of the related TODOs.

I was originally planning to define it within `BlockFrequencyInfoImpl`
(or `BFIIBase`), but it seems cleaner in a namespace.  Besides,
`isPodLike` needs to be specialized before `BlockMass` can be used in
some of the other data structures, and there isn't a clear way to do
that.

llvm-svn: 212866
2014-07-12 00:21:30 +00:00
Duncan P. N. Exon Smith b5650e5eae BFI: Mark the end of namespaces
llvm-svn: 212861
2014-07-11 23:56:50 +00:00
Hal Finkel 2e42c34d05 Allow isDereferenceablePointer to look through some bitcasts
isDereferenceablePointer should not give up upon encountering any bitcast. If
we're casting from a pointer to a larger type to a pointer to a small type, we
can continue by examining the bitcast's operand. This missing capability
was noted in a comment in the function.

In order for this to work, isDereferenceablePointer now takes an optional
DataLayout pointer (essentially all callers already had such a pointer
available). Most code uses isDereferenceablePointer though
isSafeToSpeculativelyExecute (which already took an optional DataLayout
pointer), and to enable the LICM test case, LICM needs to actually provide its DL
pointer to isSafeToSpeculativelyExecute (which it was not doing previously).

llvm-svn: 212686
2014-07-10 05:27:53 +00:00
Hal Finkel 8ae0f8d618 Improve BasicAA CS-CS queries
BasicAA contains knowledge of certain intrinsics, such as memcpy and memset,
and uses that information to form more-accurate answers to CallSite vs. Loc
ModRef queries. Unfortunately, it did not use this information when answering
CallSite vs. CallSite queries.

Generically, when an intrinsic takes one or more pointers and the intrinsic is
marked only to read/write from its arguments, the offset/size is unknown. As a
result, the generic code that answers CallSite vs. CallSite (and CallSite vs.
Loc) queries in AA uses UnknownSize when forming Locs from an intrinsic's
arguments. While BasicAA's CallSite vs. Loc override could use more-accurate
size information for some intrinsics, it did not do the same for CallSite vs.
CallSite queries.

This change refactors the intrinsic-specific logic in BasicAA into a generic AA
query function: getArgLocation, which is overridden by BasicAA to supply the
intrinsic-specific knowledge, and used by AA's generic implementation. This
allows the intrinsic-specific knowledge to be used by both CallSite vs. Loc and
CallSite vs. CallSite queries, and simplifies the BasicAA implementation.

Currently, only one function, Mac's memset_pattern16, is handled by BasicAA
(all the rest are intrinsics). As a side-effect of this refactoring, BasicAA's
getModRefBehavior override now also returns OnlyAccessesArgumentPointees for
this function (which is an improvement).

llvm-svn: 212572
2014-07-08 23:16:49 +00:00
Sanjay Patel 784a5a41e7 fixed typos in comments
llvm-svn: 212424
2014-07-06 23:24:53 +00:00
David Majnemer 651ed5e8fd InstSimplify: Fix a bug when INT_MIN is in a sdiv
When INT_MIN is the numerator in a sdiv, we would not properly handle
overflow when calculating the bounds of possible values; abs(INT_MIN) is
not a meaningful number.

Instead, check and handle INT_MIN by reasoning that the largest value is
INT_MIN/-2 and the smallest value is INT_MIN.

This fixes PR20199.

llvm-svn: 212307
2014-07-04 00:23:39 +00:00