Summary:
In order to avoid calling pow function we generate repeated fmul when n is a
positive or negative whole number.
For each exponent we pre-compute Addition Chains in order to minimize the no.
of fmuls.
Refer: http://wwwhomes.uni-bielefeld.de/achim/addition_chain.html
We pre-compute addition chains for exponents upto 32 (which results in a max of
7 fmuls).
For eg:
4 = 2+2
5 = 2+3
6 = 3+3 and so on
Hence,
pow(x, 4.0) ==> y = fmul x, x
x = fmul y, y
ret x
For negative exponents, we simply compute the reciprocal of the final result.
Note: This transformation is only enabled under fast-math.
Patch by Mandeep Singh Grang <mgrang@codeaurora.org>
Reviewers: weimingz, majnemer, escha, davide, scanon, joerg
Subscribers: probinson, escha, llvm-commits
Differential Revision: http://reviews.llvm.org/D13994
llvm-svn: 254776
The difference is that now we don't error on out-of-comdat access to
internal global values. We copy them instead. This seems to match the
expectation of COFF linkers (see pr25686).
Original message:
Start deciding earlier what to link.
A traditional linker is roughly split in symbol resolution and
"copying
stuff".
The two tasks are badly mixed in lib/Linker.
This starts splitting them apart.
With this patch there are no direct call to linkGlobalValueBody or
linkGlobalValueProto. Everything is linked via WapValue.
This also includes a few fixes:
* A GV goes undefined if the comdat is dropped (comdat11.ll).
* We error if an internal GV goes undefined (comdat13.ll).
* We don't link an unused comdat.
The first two match the behavior of an ELF linker. The second one is
equivalent to running globaldce on the input.
llvm-svn: 254418
A traditional linker is roughly split in symbol resolution and "copying
stuff".
The two tasks are badly mixed in lib/Linker.
This starts splitting them apart.
With this patch there are no direct call to linkGlobalValueBody or
linkGlobalValueProto. Everything is linked via WapValue.
This also includes a few fixes:
* A GV goes undefined if the comdat is dropped (comdat11.ll).
* We error if an internal GV goes undefined (comdat13.ll).
* We don't link an unused comdat.
The first two match the behavior of an ELF linker. The second one is
equivalent to running globaldce on the input.
llvm-svn: 254336
This one is enabled only under -ffast-math. There are cases where the
difference between the value computed and the correct value is huge
even for ffast-math, e.g. as Steven pointed out:
x = -1, y = -4
log(pow(-1), 4) = 0
4*log(-1) = NaN
I checked what GCC does and apparently they do the same optimization
(which result in the dramatic difference). Future work might try to
make this (slightly) less worse.
Differential Revision: http://reviews.llvm.org/D14400
llvm-svn: 254263
Now the ValueMapper has two callbacks. The first one maps the
declaration. The ValueMapper records the mapping and then materializes
the body/initializer.
llvm-svn: 254209
Summary:
Followed the guidelines in:
http://llvm.org/docs/CodingStandards.html#include-style
However, I noticed that uppercase named headers come before lowercase ones
throughout the codebase. So kept them as is.
Patch by Mandeep Singh Grang <mgrang@codeaurora.org>
Reviewers: majnemer, davide, jmolloy, atrick
Subscribers: sanjoy
Differential Revision: http://reviews.llvm.org/D14939
llvm-svn: 254005
The change exposed a bug in IndVarSimplify (PR25578), which led to a
failure (PR25538). When the bug is fixed, this patch can be reapplied.
The tests are kept in tree, as they're useful anyway, and will not break
with this revert.
llvm-svn: 253596
Summary: The new algorithm is more efficient (O(n), n is number of basic blocks). And it is guaranteed to cover all cases of multiple BB mapped to same line.
Reviewers: dblaikie, davidxl, dnovillo
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D14738
llvm-svn: 253594
Note, this was reviewed (and more details are in) http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html
These intrinsics currently have an explicit alignment argument which is
required to be a constant integer. It represents the alignment of the
source and dest, and so must be the minimum of those.
This change allows source and dest to each have their own alignments
by using the alignment attribute on their arguments. The alignment
argument itself is removed.
There are a few places in the code for which the code needs to be
checked by an expert as to whether using only src/dest alignment is
safe. For those places, they currently take the minimum of src/dest
alignments which matches the current behaviour.
For example, code which used to read:
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %dest, i8* %src, i32 500, i32 8, i1 false)
will now read:
call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 8 %dest, i8* align 8 %src, i32 500, i1 false)
For out of tree owners, I was able to strip alignment from calls using sed by replacing:
(call.*llvm\.memset.*)i32\ [0-9]*\,\ i1 false\)
with:
$1i1 false)
and similarly for memmove and memcpy.
I then added back in alignment to test cases which needed it.
A similar commit will be made to clang which actually has many differences in alignment as now
IRBuilder can generate different source/dest alignments on calls.
In IRBuilder itself, a new argument was added. Instead of calling:
CreateMemCpy(Dst, Src, getInt64(Size), DstAlign, /* isVolatile */ false)
you now call
CreateMemCpy(Dst, Src, getInt64(Size), DstAlign, SrcAlign, /* isVolatile */ false)
There is a temporary class (IntegerAlignment) which takes the source alignment and rejects
implicit conversion from bool. This is to prevent isVolatile here from passing its default
parameter to the source alignment.
Note, changes in future can now be made to codegen. I didn't change anything here, but this
change should enable better memcpy code sequences.
Reviewed by Hal Finkel.
llvm-svn: 253511
Summary:
This change teaches LLVM's inliner to track and suitably adjust
deoptimization state (tracked via deoptimization operand bundles) as it
inlines through call sites. The operation is described in more detail
in the LangRef changes.
Reviewers: reames, majnemer, chandlerc, dexonsmith
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D14552
llvm-svn: 253438
In r253126 we stopped to recompute LCSSA after loop unrolling in all
cases, except the unrolling is full and at least one of the loop exits
is outside the parent loop. In other cases the transformation should not
break LCSSA, but it turned out, that we also call SimplifyLoop on the
parent loop, which might break LCSSA by itself. This fix just triggers
LCSSA recomputation in this case as well.
I'm committing it without a test case for now, but I'll try to invent
one. It's a bit tricky because in an isolated test LoopSimplify would
be scheduled before LoopUnroll, and thus will change the test and hide
the problem.
llvm-svn: 253253
Summary:
This fails a check in Verifier.cpp, which checks for location matches between the declared
variable and the !dbg attachments.
Reviewers: dnovillo, dblaikie, danielcdh
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D14657
llvm-svn: 253194
Summary: The Old personality function gets copied over, but the
Materializer didn't have a chance to inspect it (e.g. to fix up
references to the correct module for the target function).
Also add a verifier check that makes sure the personality routine
is in the same module as the function whose personality it is.
Reviewers: majnemer
Subscribers: jevinskie, llvm-commits
Differential Revision: http://reviews.llvm.org/D14474
llvm-svn: 253183
Summary:
The patch to move metadata linking after global value linking didn't
correctly map unmaterialized global values to null as desired. They
were in fact mapped to the source copy. It largely worked by accident
since most module linker clients destroyed the source module which
caused the source GVs to be replaced by null, but caused a failure with
LTO linking on Windows:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312869.html
The problem is that a null return value from materializeValueFor is
handled by mapping the value to self. This is the desired behavior when
materializeValueFor is passed a non-GlobalValue. The problem is how to
distinguish that case from the case where we really do want to map to
null.
This patch addresses this by passing in a new flag to the value mapper
indicating that unmapped global values should be mapped to null. Other
Value types are handled as before.
Note that the documented behavior of asserting on unmapped values when
the flag RF_IgnoreMissingValues isn't set is currently disabled with
FIXME notes due to bootstrap failures. I modified these disabled asserts
so when they are eventually enabled again it won't assert for the
unmapped values when the new RF_NullMapMissingGlobalValues flag is set.
I also considered using a callback into the value materializer, but a
flag seemed cleaner given that there are already existing flags.
I also considered modifying materializeValueFor to return the input
value when we want to map to source and then treat a null return
to mean map to null. However, there are other value materializer
subclasses that implement materializeValueFor, and they would all need
to be audited and the return values possibly changed, which seemed
error-prone.
Reviewers: dexonsmith, joker.eph
Subscribers: pcc, llvm-commits
Differential Revision: http://reviews.llvm.org/D14682
llvm-svn: 253170
Summary:
Currently we always recompute LCSSA for outer loops after unrolling an
inner loop. That leads to compile time problem when we have big loop
nests, and we can solve it by avoiding unnecessary work. For instance,
if w eonly do partial unrolling, we don't break LCSSA, so we don't need
to rebuild it. Also, if all exits from the inner loop are inside the
enclosing loop, then complete unrolling won't break LCSSA either.
I replaced unconditional LCSSA recomputation with conditional recomputation +
unconditional assert and added several tests, which were failing when I
experimented with it.
Soon I plan to follow up with a similar patch for recalculation of dominators
tree.
Reviewers: hfinkel, dexonsmith, bogner, joker.eph, chandlerc
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D14526
llvm-svn: 253126
The discriminators pass relied on the presence of llvm.dbg.cu to decide
whether to add discriminators, but this fails in the case where debug
info is only enabled partially when -fprofile-sample-use is active.
The reason llvm.dbg.cu is not present in these cases is to prevent
codegen from emitting debug info (as it is only used for the sample
profile pass).
This changes the discriminators pass to also emit discriminators even
when debug info is not being emitted.
llvm-svn: 252763
This is fix for PR24059.
When we are hoisting instruction above some condition it may turn out
that metadata on this instruction was control dependant on the condition.
This metadata becomes invalid and we need to drop it.
This patch should cover most obvious places of speculative execution (which
I have found by greping isSafeToSpeculativelyExecute). I think there are more
cases but at least this change covers the severe ones.
Differential Revision: http://reviews.llvm.org/D14398
llvm-svn: 252604
Summary: Call instructions that are from the same line and same basic block needs to have separate discriminators to distinguish between different callsites.
Reviewers: davidxl, dnovillo, dblaikie
Subscribers: dblaikie, probinson, llvm-commits
Differential Revision: http://reviews.llvm.org/D14464
llvm-svn: 252492
Summary:
LAA currently generates a set of SCEV predicates that must be checked by users.
In the case of Loop Distribute/Loop Load Elimination, no such predicates could have
been emitted, since we don't allow stride versioning. However, in the future there
could be SCEV predicates that will need to be checked.
This change adds support for SCEV predicate versioning in the Loop Distribute, Loop
Load Eliminate and the loop versioning infrastructure.
Reviewers: anemet
Subscribers: mssimpso, sanjoy, llvm-commits
Differential Revision: http://reviews.llvm.org/D14240
llvm-svn: 252467
Some implicit ilist iterator conversions have crept back into Analysis,
Transforms, Hexagon, and llvm-stress. This removes them.
I'll commit a patch immediately after this to disallow them (in a
separate patch so that it's easy to revert if necessary).
llvm-svn: 252371
Summary:
This change makes the `isImpliedCondition` interface similar to the rest
of the functions in ValueTracking (in that it takes a DataLayout,
AssumptionCache etc.). This is an NFC, intended to make a later diff
less noisy.
Depends on D14369
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D14391
llvm-svn: 252333
Previously, subprograms contained a metadata reference to the function they
described. Because most clients need to get or set a subprogram for a given
function rather than the other way around, this created unneeded inefficiency.
For example, many passes needed to call the function llvm::makeSubprogramMap()
to build a mapping from functions to subprograms, and the IR linker needed to
fix up function references in a way that caused quadratic complexity in the IR
linking phase of LTO.
This change reverses the direction of the edge by storing the subprogram as
function-level metadata and removing DISubprogram's function field.
Since this is an IR change, a bitcode upgrade has been provided.
Fixes PR23367. An upgrade script for textual IR for out-of-tree clients is
attached to the PR.
Differential Revision: http://reviews.llvm.org/D14265
llvm-svn: 252219
We were correctly skipping dbginfo intrinsics and terminators, but the initial bailout wasn't, causing it to bail out on almost any block.
llvm-svn: 252152
We can often end up with conditional stores that cannot be speculated. They can come from fairly simple, idiomatic code:
if (c & flag1)
*a = x;
if (c & flag2)
*a = y;
...
There is no dominating or post-dominating store to a, so it is not legal to move the store unconditionally to the end of the sequence and cache the intermediate result in a register, as we would like to.
It is, however, legal to merge the stores together and do the store once:
tmp = undef;
if (c & flag1)
tmp = x;
if (c & flag2)
tmp = y;
if (c & flag1 || c & flag2)
*a = tmp;
The real power in this optimization is that it allows arbitrary length ladders such as these to be completely and trivially if-converted. The typical code I'd expect this to trigger on often uses binary-AND with constants as the condition (as in the above example), which means the ending condition can simply be truncated into a single binary-AND too: 'if (c & (flag1|flag2))'. As in the general case there are bitwise operators here, the ladder can often be optimized further too.
This optimization involves potentially increasing register pressure. Even in the simplest case, the lifetime of the first predicate is extended. This can be elided in some cases such as using binary-AND on constants, but not in the general case. Threading 'tmp' through all branches can also increase register pressure.
The optimization as in this patch is enabled by default but kept in a very conservative mode. It will only optimize if it thinks the resultant code should be if-convertable, and additionally if it can thread 'tmp' through at least one existing PHI, so it will only ever in the worst case create one more PHI and extend the lifetime of a predicate.
This doesn't trigger much in LNT, unfortunately, but it does trigger in a big way in a third party test suite.
llvm-svn: 252051
Weiming Zhao