[InstSimplify] Add additional checks when substituting pointers #125385
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Related issue: #34577 |
llvmbot
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llvm:instcombine
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@llvm/pr-subscribers-llvm-transforms @llvm/pr-subscribers-llvm-analysis Author: Yingwei Zheng (dtcxzyw) ChangesCompile-time impact: https://llvm-compile-time-tracker.com/compare.php?from=d09b521624f263b5f1296f8d4771836b97e600cb&to=e437ba2cb83bb965e13ef00727671896f03ff84f&stat=instructions:u Full diff: https://github.com/llvm/llvm-project/pull/125385.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 21c937530cd869..3cbc4107433ef3 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -27,6 +27,7 @@
#include "llvm/Analysis/CmpInstAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstSimplifyFolder.h"
+#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/LoopAnalysisManager.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/OverflowInstAnalysis.h"
@@ -4731,12 +4732,16 @@ static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
// the arms of the select. See if substituting this value into the arm and
// simplifying the result yields the same value as the other arm.
if (Pred == ICmpInst::ICMP_EQ) {
- if (Value *V = simplifySelectWithEquivalence({{CmpLHS, CmpRHS}}, TrueVal,
- FalseVal, Q, MaxRecurse))
- return V;
- if (Value *V = simplifySelectWithEquivalence({{CmpRHS, CmpLHS}}, TrueVal,
- FalseVal, Q, MaxRecurse))
- return V;
+ if (CmpLHS->getType()->isIntOrIntVectorTy() ||
+ canReplacePointersIfEqual(CmpLHS, CmpRHS, Q.DL))
+ if (Value *V = simplifySelectWithEquivalence({{CmpLHS, CmpRHS}}, TrueVal,
+ FalseVal, Q, MaxRecurse))
+ return V;
+ if (CmpLHS->getType()->isIntOrIntVectorTy() ||
+ canReplacePointersIfEqual(CmpRHS, CmpLHS, Q.DL))
+ if (Value *V = simplifySelectWithEquivalence({{CmpRHS, CmpLHS}}, TrueVal,
+ FalseVal, Q, MaxRecurse))
+ return V;
Value *X;
Value *Y;
diff --git a/llvm/test/Transforms/InstSimplify/select-icmp.ll b/llvm/test/Transforms/InstSimplify/select-icmp.ll
index a6ef937760a589..9895271b35ac7f 100755
--- a/llvm/test/Transforms/InstSimplify/select-icmp.ll
+++ b/llvm/test/Transforms/InstSimplify/select-icmp.ll
@@ -244,3 +244,23 @@ cond.true: ; preds = %entry
cond.end: ; preds = %entry, %cond.true
ret i8 0
}
+
+define ptr @icmp_ptr_eq_replace(ptr %a, ptr %b) {
+; CHECK-LABEL: @icmp_ptr_eq_replace(
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq ptr [[A:%.*]], [[B1:%.*]]
+; CHECK-NEXT: [[B:%.*]] = select i1 [[CMP]], ptr [[A]], ptr [[B1]]
+; CHECK-NEXT: ret ptr [[B]]
+;
+ %cmp = icmp eq ptr %a, %b
+ %sel = select i1 %cmp, ptr %a, ptr %b
+ ret ptr %sel
+}
+
+define ptr @icmp_ptr_eq_replace_null(ptr %a) {
+; CHECK-LABEL: @icmp_ptr_eq_replace_null(
+; CHECK-NEXT: ret ptr [[A:%.*]]
+;
+ %cmp = icmp eq ptr %a, null
+ %sel = select i1 %cmp, ptr null, ptr %a
+ ret ptr %sel
+}
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nikic
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Feb 2, 2025
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LGTM, but please add a positive test where both pointers have the same underlying object.
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/cherry-pick 1af627b |
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/pull-request #125398 |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/190/builds/13947 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/51/builds/10203 Here is the relevant piece of the build log for the reference |
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Feb 11, 2025
…#125385) Compile-time impact: https://llvm-compile-time-tracker.com/compare.php?from=d09b521624f263b5f1296f8d4771836b97e600cb&to=e437ba2cb83bb965e13ef00727671896f03ff84f&stat=instructions:u IR diff looks acceptable. Closes llvm#115574 (cherry picked from commit 1af627b)
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Compile-time impact: https://llvm-compile-time-tracker.com/compare.php?from=d09b521624f263b5f1296f8d4771836b97e600cb&to=e437ba2cb83bb965e13ef00727671896f03ff84f&stat=instructions:u
IR diff looks acceptable.
Closes #115574