[ConstantFold] Special case log1p +/-0.0 #114635
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This reverts commit 900b636.
C's Annex F specifies that log1p +/-0.0 returns the input value; however, this behavior is optional and host C libraries may behave differently. This change applies the Annex F behavior to constant folding by LLVM.
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@llvm/pr-subscribers-llvm-transforms Author: Hubert Tong (hubert-reinterpretcast) ChangesC's Annex F specifies that log1p +/-0.0 returns the input value; Full diff: https://github.com/llvm/llvm-project/pull/114635.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index c5a2c2f52f8dc2..88db315ffd0bcb 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -2407,6 +2407,9 @@ static Constant *ConstantFoldScalarCall1(StringRef Name,
break;
case LibFunc_log1p:
case LibFunc_log1pf:
+ // Implement optional behavior from C's Annex F for +/-0.0.
+ if (U.isZero())
+ return ConstantFP::get(Ty->getContext(), U);
if (APF > APFloat::getOne(APF.getSemantics(), true) && TLI->has(Func))
return ConstantFoldFP(log1p, APF, Ty);
break;
diff --git a/llvm/test/Transforms/InstCombine/log1p.ll b/llvm/test/Transforms/InstCombine/log1p.ll
index bbf89db8c34105..81d3cc8a4f7ac9 100644
--- a/llvm/test/Transforms/InstCombine/log1p.ll
+++ b/llvm/test/Transforms/InstCombine/log1p.ll
@@ -1,4 +1,3 @@
-; XFAIL: target={{.*}}-aix{{.*}}
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt < %s -passes=instcombine -S | FileCheck %s
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@llvm/pr-subscribers-llvm-analysis Author: Hubert Tong (hubert-reinterpretcast) ChangesC's Annex F specifies that log1p +/-0.0 returns the input value; Full diff: https://github.com/llvm/llvm-project/pull/114635.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index c5a2c2f52f8dc2..88db315ffd0bcb 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -2407,6 +2407,9 @@ static Constant *ConstantFoldScalarCall1(StringRef Name,
break;
case LibFunc_log1p:
case LibFunc_log1pf:
+ // Implement optional behavior from C's Annex F for +/-0.0.
+ if (U.isZero())
+ return ConstantFP::get(Ty->getContext(), U);
if (APF > APFloat::getOne(APF.getSemantics(), true) && TLI->has(Func))
return ConstantFoldFP(log1p, APF, Ty);
break;
diff --git a/llvm/test/Transforms/InstCombine/log1p.ll b/llvm/test/Transforms/InstCombine/log1p.ll
index bbf89db8c34105..81d3cc8a4f7ac9 100644
--- a/llvm/test/Transforms/InstCombine/log1p.ll
+++ b/llvm/test/Transforms/InstCombine/log1p.ll
@@ -1,4 +1,3 @@
-; XFAIL: target={{.*}}-aix{{.*}}
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt < %s -passes=instcombine -S | FileCheck %s
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arsenm
approved these changes
Nov 2, 2024
c8ef
approved these changes
Nov 2, 2024
hubert-reinterpretcast
deleted the
users/hubert-reinterpretcast/ConstantFold-log1pZeroCases
branch
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/42/builds/1739 Here is the relevant piece of the build log for the reference |
smallp-o-p
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Nov 3, 2024
C's Annex F specifies that log1p +/-0.0 returns the input value; however, this behavior is optional and host C libraries may behave differently. This change applies the Annex F behavior to constant folding by LLVM.
NoumanAmir657
pushed a commit
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Nov 4, 2024
C's Annex F specifies that log1p +/-0.0 returns the input value; however, this behavior is optional and host C libraries may behave differently. This change applies the Annex F behavior to constant folding by LLVM.
PhilippRados
pushed a commit
to PhilippRados/llvm-project
that referenced
this pull request
Nov 6, 2024
C's Annex F specifies that log1p +/-0.0 returns the input value; however, this behavior is optional and host C libraries may behave differently. This change applies the Annex F behavior to constant folding by LLVM.
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C's Annex F specifies that log1p +/-0.0 returns the input value;
however, this behavior is optional and host C libraries may behave
differently. This change applies the Annex F behavior to constant
folding by LLVM.