This is a minimal patch to avoid the infinite loop in:
https://llvm.org/bugs/show_bug.cgi?id=31751
But the general problem is bigger: we're not canonicalizing all of the min/max forms reported
by value tracking's matchSelectPattern(), and we don't define min/max consistently. Some code
uses matchSelectPattern(), other code uses matchers like m_Umax, and others have their own
inline definitions which may be subtly different from any of the above.
The reason that the test cases in this patch need a cast op to trigger is because we don't
(yet) canonicalize all min/max forms based on matchSelectPattern() in
canonicalizeMinMaxWithConstant(), but we do make min/max+cast transforms based on
matchSelectPattern() in visitSelectInst().
The location of the icmp transforms that trigger the inf-loop seems arbitrary at best, so
I'm moving those behind the min/max fence in visitICmpInst() as the quick fix.
llvm-svn: 293345
Summary:
There are many NVVM intrinsics that we can't entirely get rid of, but
that nonetheless often correspond to target-generic LLVM intrinsics.
For example, if flush denormals to zero (ftz) is enabled, we can convert
@llvm.nvvm.ceil.ftz.f to @llvm.ceil.f32. On the other hand, if ftz is
disabled, we can't do this, because @llvm.ceil.f32 will be lowered to a
non-ftz PTX instruction. In this case, we can, however, simplify the
non-ftz nvvm ceil intrinsic, @llvm.nvvm.ceil.f, to @llvm.ceil.f32.
These transformations are particularly useful because they let us
constant fold instructions that appear in libdevice, the bitcode library
that ships with CUDA and essentially functions as its libm.
Reviewers: tra
Subscribers: hfinkel, majnemer, llvm-commits
Differential Revision: https://reviews.llvm.org/D28794
llvm-svn: 293244
This change reverts:
r293061: "[InstCombine] Canonicalize guards for NOT OR condition"
r293058: "[InstCombine] Canonicalize guards for AND condition"
They miscompile cases like:
```
declare void @llvm.experimental.guard(i1, ...)
define void @test_guard_not_or(i1 %A, i1 %B) {
%C = or i1 %A, %B
%D = xor i1 %C, true
call void(i1, ...) @llvm.experimental.guard(i1 %D, i32 20, i32 30)[ "deopt"() ]
ret void
}
```
because they do transfer the `i32 20, i32 30` parameters to newly
created guard instructions.
llvm-svn: 293227
We already have this fold when the lshr has one use, but it doesn't need that
restriction. We may be able to remove some code from foldShiftedShift().
Also, move the similar:
(X << C) >>u C --> X & (-1 >>u C)
...directly into visitLShr to help clean up foldShiftByConstOfShiftByConst().
That whole function seems questionable since it is called by commonShiftTransforms(),
but there's really not much in common if we're checking the shift opcodes for every
fold.
llvm-svn: 293215
This is a partial fix for Bug 31520 - [guards] canonicalize guards in instcombine
Reviewed By: apilipenko
Differential Revision: https://reviews.llvm.org/D29075
Patch by Maxim Kazantsev.
llvm-svn: 293061
This is a partial fix for Bug 31520 - [guards] canonicalize guards in instcombine
Reviewed By: apilipenko
Differential Revision: https://reviews.llvm.org/D29074
Patch by Maxim Kazantsev.
llvm-svn: 293058
This is a partial fix for Bug 31520 - [guards] canonicalize guards in instcombine
Reviewed By: majnemer, apilipenko
Differential Revision: https://reviews.llvm.org/D29071
Patch by Maxim Kazantsev.
llvm-svn: 293056
We may be able to assert that no shl-shl or lshr-lshr pairs ever get here
because we should have already handled those in foldShiftedShift().
llvm-svn: 292726
Summary:
Currently we return undef, but we're in the process of changing the
LangRef so that llvm.sqrt behaves like the other math intrinsics,
matching the return value of the standard libcall but not setting errno.
This change is legal even without the LangRef change because currently
calling llvm.sqrt(x) where x is negative is spec'ed to be UB. But in
practice it's also safe because we're simply constant-folding fewer
inputs: Inputs >= -0 get constant-folded as before, but inputs < -0 now
aren't constant-folded, because ConstantFoldFP aborts if the host math
function raises an fp exception.
Reviewers: hfinkel, efriedma, sanjoy
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D28929
llvm-svn: 292692
Unfortunately, recognizing these in value tracking may cause us to hit
a hack in InstCombiner::visitICmpInst() more often:
http://lists.llvm.org/pipermail/llvm-dev/2017-January/109340.html
...but besides being the obviously Right Thing To Do, there's a clear
codegen win from identifying these patterns for several targets.
llvm-svn: 292655
Simplify a packss/packus truncation based on the elements of the mask that are actually demanded.
Differential Revision: https://reviews.llvm.org/D28777
llvm-svn: 292591
Also, add the corresponding match to the AssumptionCache's 'Affected Values' list.
Differential Revision: https://reviews.llvm.org/D28485
llvm-svn: 292239
Add missing fabs(fpext) optimzation that worked with the call,
and also fixes it creating a second fpext when there were multiple
uses.
llvm-svn: 292172
Simplify a pshufb shuffle mask based on the elements of the mask that are actually demanded.
Differential Revision: https://reviews.llvm.org/D28745
llvm-svn: 292101
Sanjay Patel