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| author | Sanjay Patel <spatel@rotateright.com> | 2018-08-02 13:46:20 +0000 |
|---|---|---|
| committer | Sanjay Patel <spatel@rotateright.com> | 2018-08-02 13:46:20 +0000 |
| commit | f9a0d593e9da6d7d16ae2f5b073eb6598bc35875 (patch) | |
| tree | 431bb60d541f1fbf347705679c58f119f2a17171 /llvm/test/Transforms/InstSimplify | |
| parent | 1f3977a856a3313a028a2505ec9a59950204a5a1 (diff) | |
| download | bcm5719-llvm-f9a0d593e9da6d7d16ae2f5b073eb6598bc35875.tar.gz bcm5719-llvm-f9a0d593e9da6d7d16ae2f5b073eb6598bc35875.zip | |
[ValueTracking] fix maxnum miscompile for cannotBeOrderedLessThanZero (PR37776)
This adds the NAN checks suggested in PR37776:
https://bugs.llvm.org/show_bug.cgi?id=37776
If both operands to maxnum are NAN, that should get constant folded, so we don't
have to handle that case. This is the same assumption as other FP ops in this
function. Returning 'false' is always conservatively correct.
Copying from the bug report:
Currently, we have this for "when is cannotBeOrderedLessThanZero
(mustBePositiveOrNaN) true for maxnum":
L
-------------------
| Pos | Neg | NaN |
------------------------
|Pos | x | x | x |
------------------------
R |Neg | x | | x |
------------------------
|NaN | x | x | x |
------------------------
The cases with (Neg & NaN) are wrong. We should have:
L
-------------------
| Pos | Neg | NaN |
------------------------
|Pos | x | x | x |
------------------------
R |Neg | x | | |
------------------------
|NaN | x | | x |
------------------------
Differential Revision: https://reviews.llvm.org/D50081
llvm-svn: 338716
Diffstat (limited to 'llvm/test/Transforms/InstSimplify')
| -rw-r--r-- | llvm/test/Transforms/InstSimplify/floating-point-compare.ll | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/llvm/test/Transforms/InstSimplify/floating-point-compare.ll b/llvm/test/Transforms/InstSimplify/floating-point-compare.ll index b1444bb5a1e..bc5c58a698e 100644 --- a/llvm/test/Transforms/InstSimplify/floating-point-compare.ll +++ b/llvm/test/Transforms/InstSimplify/floating-point-compare.ll @@ -266,13 +266,15 @@ define i1 @orderedLessZeroMinNum(float, float) { ret i1 %uge } -; FIXME: This is wrong. ; PR37776: https://bugs.llvm.org/show_bug.cgi?id=37776 ; exp() may return nan, leaving %1 as the unknown result, so we can't simplify. define i1 @orderedLessZeroMaxNum(float, float) { ; CHECK-LABEL: @orderedLessZeroMaxNum( -; CHECK-NEXT: ret i1 true +; CHECK-NEXT: [[A:%.*]] = call float @llvm.exp.f32(float [[TMP0:%.*]]) +; CHECK-NEXT: [[B:%.*]] = call float @llvm.maxnum.f32(float [[A]], float [[TMP1:%.*]]) +; CHECK-NEXT: [[UGE:%.*]] = fcmp uge float [[B]], 0.000000e+00 +; CHECK-NEXT: ret i1 [[UGE]] ; %a = call float @llvm.exp.f32(float %0) %b = call float @llvm.maxnum.f32(float %a, float %1) |
