Commit Graph

42 Commits

Author SHA1 Message Date
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
Craig Topper 9f008867c0 [C++11] More 'nullptr' conversion. In some cases just using a boolean check instead of comparing to nullptr.
llvm-svn: 206243
2014-04-15 04:59:12 +00:00
Chandler Carruth cdf4788401 [C++11] Add range based accessors for the Use-Def chain of a Value.
This requires a number of steps.
1) Move value_use_iterator into the Value class as an implementation
   detail
2) Change it to actually be a *Use* iterator rather than a *User*
   iterator.
3) Add an adaptor which is a User iterator that always looks through the
   Use to the User.
4) Wrap these in Value::use_iterator and Value::user_iterator typedefs.
5) Add the range adaptors as Value::uses() and Value::users().
6) Update *all* of the callers to correctly distinguish between whether
   they wanted a use_iterator (and to explicitly dig out the User when
   needed), or a user_iterator which makes the Use itself totally
   opaque.

Because #6 requires churning essentially everything that walked the
Use-Def chains, I went ahead and added all of the range adaptors and
switched them to range-based loops where appropriate. Also because the
renaming requires at least churning every line of code, it didn't make
any sense to split these up into multiple commits -- all of which would
touch all of the same lies of code.

The result is still not quite optimal. The Value::use_iterator is a nice
regular iterator, but Value::user_iterator is an iterator over User*s
rather than over the User objects themselves. As a consequence, it fits
a bit awkwardly into the range-based world and it has the weird
extra-dereferencing 'operator->' that so many of our iterators have.
I think this could be fixed by providing something which transforms
a range of T&s into a range of T*s, but that *can* be separated into
another patch, and it isn't yet 100% clear whether this is the right
move.

However, this change gets us most of the benefit and cleans up
a substantial amount of code around Use and User. =]

llvm-svn: 203364
2014-03-09 03:16:01 +00:00
Rafael Espindola 7c68bebb9c Rename some member variables from TD to DL.
TargetData was renamed DataLayout back in r165242.

llvm-svn: 201581
2014-02-18 15:33:12 +00:00
Chandler Carruth 5ad5f15cff [cleanup] Move the Dominators.h and Verifier.h headers into the IR
directory. These passes are already defined in the IR library, and it
doesn't make any sense to have the headers in Analysis.

Long term, I think there is going to be a much better way to divide
these matters. The dominators code should be fully separated into the
abstract graph algorithm and have that put in Support where it becomes
obvious that evn Clang's CFGBlock's can use it. Then the verifier can
manually construct dominance information from the Support-driven
interface while the Analysis library can provide a pass which both
caches, reconstructs, and supports a nice update API.

But those are very long term, and so I don't want to leave the really
confusing structure until that day arrives.

llvm-svn: 199082
2014-01-13 09:26:24 +00:00
Alp Toker f907b891da Correct word hyphenations
This patch tries to avoid unrelated changes other than fixing a few
hyphen-related ambiguities and contractions in nearby lines.

llvm-svn: 196471
2013-12-05 05:44:44 +00:00
Chandler Carruth 9fb823bbd4 Move all of the header files which are involved in modelling the LLVM IR
into their new header subdirectory: include/llvm/IR. This matches the
directory structure of lib, and begins to correct a long standing point
of file layout clutter in LLVM.

There are still more header files to move here, but I wanted to handle
them in separate commits to make tracking what files make sense at each
layer easier.

The only really questionable files here are the target intrinsic
tablegen files. But that's a battle I'd rather not fight today.

I've updated both CMake and Makefile build systems (I think, and my
tests think, but I may have missed something).

I've also re-sorted the includes throughout the project. I'll be
committing updates to Clang, DragonEgg, and Polly momentarily.

llvm-svn: 171366
2013-01-02 11:36:10 +00:00
Chandler Carruth ed0881b2a6 Use the new script to sort the includes of every file under lib.
Sooooo many of these had incorrect or strange main module includes.
I have manually inspected all of these, and fixed the main module
include to be the nearest plausible thing I could find. If you own or
care about any of these source files, I encourage you to take some time
and check that these edits were sensible. I can't have broken anything
(I strictly added headers, and reordered them, never removed), but they
may not be the headers you'd really like to identify as containing the
API being implemented.

Many forward declarations and missing includes were added to a header
files to allow them to parse cleanly when included first. The main
module rule does in fact have its merits. =]

llvm-svn: 169131
2012-12-03 16:50:05 +00:00
Manman Ren 49d684e1e2 Release build: guard dump functions with
"#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)"

No functional change. Update r163344.

llvm-svn: 163679
2012-09-12 05:06:18 +00:00
Manman Ren c3366ccecb Release build: guard dump functions with "ifndef NDEBUG"
No functional change.

llvm-svn: 163344
2012-09-06 19:55:56 +00:00
Duncan Sands b8cee00841 Uniformize the InstructionSimplify interface by ensuring that all routines
take a TargetLibraryInfo parameter.  Internally, rather than passing TD, TLI
and DT parameters around all over the place, introduce a struct for holding
them.

llvm-svn: 152623
2012-03-13 11:42:19 +00:00
David Blaikie 46a9f016c5 More dead code removal (using -Wunreachable-code)
llvm-svn: 148578
2012-01-20 21:51:11 +00:00
Dan Gohman 75d7d5e988 Move Instruction::isSafeToSpeculativelyExecute out of VMCore and
into Analysis as a standalone function, since there's no need for
it to be in VMCore. Also, update it to use isKnownNonZero and
other goodies available in Analysis, making it more precise,
enabling more aggressive optimization.

llvm-svn: 146610
2011-12-14 23:49:11 +00:00
Chad Rosier c24b86ffbe Propagate TargetLibraryInfo throughout ConstantFolding.cpp and
InstructionSimplify.cpp.  Other fixups as needed.
Part of rdar://10500969

llvm-svn: 145559
2011-12-01 03:08:23 +00:00
Frits van Bommel ede0dc6dda Shorten some expressions by using ArrayRef::slice().
llvm-svn: 135910
2011-07-25 15:13:01 +00:00
Jay Foad d1b7849d49 Convert GetElementPtrInst to use ArrayRef.
llvm-svn: 135904
2011-07-25 09:48:08 +00:00
Jay Foad b992a635fb Convert SimplifyGEPInst to use ArrayRef.
llvm-svn: 135482
2011-07-19 15:07:52 +00:00
Jay Foad 7c14a558fe Don't include Operator.h from InstrTypes.h.
llvm-svn: 129271
2011-04-11 09:35:34 +00:00
Chris Lattner bf0aa927cc split dom frontier handling stuff out to its own DominanceFrontier header,
so that Dominators.h is *just* domtree.  Also prune #includes a bit.

llvm-svn: 122714
2011-01-02 22:09:33 +00:00
Dan Gohman f1ebfc1544 Strip trailing whitespace.
llvm-svn: 119706
2010-11-18 17:06:31 +00:00
Dan Gohman 0ab28b62b1 Use llvm_unreachable for "impossible" situations.
llvm-svn: 119705
2010-11-18 17:05:57 +00:00
Dan Gohman 2e1fc849b2 Add support for PHI-translating sext, zext, and trunc instructions,
enabling more PRE. PR8586.

llvm-svn: 119704
2010-11-18 17:05:13 +00:00
Duncan Sands 5ffc298bc7 In which I discover the existence of loops. Threading an operation
over a phi node by applying it to each operand may be wrong if the
operation and the phi node are mutually interdependent (the testcase
has a simple example of this).  So only do this transform if it would
be correct to perform the operation in each predecessor of the block
containing the phi, i.e. if the other operands all dominate the phi.
This should fix the FFMPEG snow.c regression reported by İsmail Dönmez.

llvm-svn: 119347
2010-11-16 12:16:38 +00:00
Daniel Dunbar 693ea89214 Reapply r97010, the speculative revert failed.
llvm-svn: 97036
2010-02-24 08:48:04 +00:00
Daniel Dunbar 0a2031e5b6 Speculatively revert r97010, "Add an argument to PHITranslateValue to specify
the DominatorTree. ...", in hopes of restoring poor old PPC bootstrap.

llvm-svn: 97027
2010-02-24 06:55:22 +00:00
Bob Wilson 66e58ac742 Add an argument to PHITranslateValue to specify the DominatorTree. If this
argument is non-null, pass it along to PHITranslateSubExpr so that it can
prefer using existing values that dominate the PredBB, instead of just
blindly picking the first equivalent value that it finds on a uselist.
Also when the DominatorTree is specified, have PHITranslateValue filter
out any result that does not dominate the PredBB.  This is basically just
refactoring the check that used to be in GetAvailablePHITranslatedSubExpr
and also in GVN.

Despite my initial expectations, this change does not affect the results
of GVN for any testcases that I could find, but it should help compile time.
Before this change, if PHITranslateSubExpr picked a value that does not
dominate, PHITranslateWithInsertion would then insert a new value, which GVN
would later determine to be redundant and would replace.  By picking a good
value to begin with, we save GVN the extra work of inserting and then
replacing a new value.

llvm-svn: 97010
2010-02-24 01:39:00 +00:00
David Greene f790593e6e Change dbgs() back to errs() as Chris requested.
llvm-svn: 92085
2009-12-23 23:27:15 +00:00
David Greene 04e7ae6a57 Convert debug messages to use dbgs(). Generally this means
s/errs/dbgs/g except for certain special cases.

llvm-svn: 92046
2009-12-23 21:06:14 +00:00
Chris Lattner 9f9010ef47 Add a minor optimization: if we haven't changed the operands of an
add, there is no need to scan the world to find the same add again.
This invalidates the previous testcase, which wasn't wonderful anyway,
because it needed a run of instcombine to permute the use-lists in 
just the right way to before GVN was run (so it was really fragile).
Not a big loss.

llvm-svn: 90973
2009-12-09 17:27:45 +00:00
Chris Lattner fa2e536831 fix PR5733, a case where we'd replace an add with a lexically identical
binary operator that wasn't an add.  In this case, a xor.  Whoops.

llvm-svn: 90971
2009-12-09 17:18:49 +00:00
Chris Lattner 9af9d0f74e fix a nasty variable that was shadowing the real CurBB but with the wrong value.
llvm-svn: 90920
2009-12-09 01:19:16 +00:00
Chris Lattner 11da6b0050 fix many input tracking bugs.
llvm-svn: 90915
2009-12-09 00:56:14 +00:00
Chris Lattner 37251f8375 fix PHI translation to take the PHI out of the instinputs set and add
the translated value back to it if an instruction.

llvm-svn: 90909
2009-12-09 00:18:13 +00:00
Chris Lattner cfd76375e3 instructions defined in CurBB may be intermediate nodes of the computation.
llvm-svn: 90908
2009-12-09 00:10:55 +00:00
Chris Lattner 0aa75680d6 add dumping and sanity checking support.
llvm-svn: 90906
2009-12-09 00:01:00 +00:00
Chris Lattner 5cf4b74b45 make sure that PHITransAddr keeps its 'InstInputs' list up to
date when instsimplify kicks in.

llvm-svn: 90901
2009-12-08 23:42:51 +00:00
Chris Lattner 6425a23c8c fix a typo (and -> add) and fix GetAvailablePHITranslatedSubExpr to not
side-effect the current object.

llvm-svn: 90837
2009-12-08 06:06:26 +00:00
Chris Lattner 9e34d156d3 fix typo
llvm-svn: 90793
2009-12-07 19:52:57 +00:00
Chris Lattner dccf7ad8b9 add accessor, improve comment.
llvm-svn: 90792
2009-12-07 19:45:30 +00:00
Chris Lattner 77b0d3b217 add support for phi translation and incorpation of new expression.
llvm-svn: 90782
2009-12-07 19:04:49 +00:00
Chris Lattner e60244db8c checkpoint of the new PHITransAddr code, still not done and not used by
anything.

llvm-svn: 90779
2009-12-07 18:36:53 +00:00
Chris Lattner b63051caf6 add the start of a class used to handle phi translation in memdep and
gvn (this is just a skeleton so far).  This will ultimately be used
to fix a nasty miscompilation with GVN.

llvm-svn: 90518
2009-12-04 02:10:16 +00:00