release/20.x: [InstSimplify] Add additional checks when substituting pointers (#125385) #125398
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@nikic What do you think about merging this PR to the release branch? |
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@llvm/pr-subscribers-llvm-transforms Author: None (llvmbot) ChangesBackport 1af627b Requested by: @dtcxzyw Full diff: https://github.com/llvm/llvm-project/pull/125398.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index d69747e30f884d7..4e550f8fa6a9fd1 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"
@@ -4737,12 +4738,16 @@ 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 a6ef937760a5899..64c0d1d7553feb9 100755
--- a/llvm/test/Transforms/InstSimplify/select-icmp.ll
+++ b/llvm/test/Transforms/InstSimplify/select-icmp.ll
@@ -244,3 +244,35 @@ 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
+}
+
+define ptr @ptr_eq_replace_same_underlying_object(ptr %st, i64 %i, i64 %j) {
+; CHECK-LABEL: @ptr_eq_replace_same_underlying_object(
+; CHECK-NEXT: [[B:%.*]] = getelementptr inbounds i8, ptr [[ST:%.*]], i64 [[J:%.*]]
+; CHECK-NEXT: ret ptr [[B]]
+;
+ %a = getelementptr inbounds i8, ptr %st, i64 %i
+ %b = getelementptr inbounds i8, ptr %st, i64 %j
+ %cmp = icmp eq ptr %a, %b
+ %sel = select i1 %cmp, ptr %a, ptr %b
+ ret ptr %sel
+}
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@llvm/pr-subscribers-llvm-analysis Author: None (llvmbot) ChangesBackport 1af627b Requested by: @dtcxzyw Full diff: https://github.com/llvm/llvm-project/pull/125398.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index d69747e30f884d..4e550f8fa6a9fd 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"
@@ -4737,12 +4738,16 @@ 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..64c0d1d7553feb 100755
--- a/llvm/test/Transforms/InstSimplify/select-icmp.ll
+++ b/llvm/test/Transforms/InstSimplify/select-icmp.ll
@@ -244,3 +244,35 @@ 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
+}
+
+define ptr @ptr_eq_replace_same_underlying_object(ptr %st, i64 %i, i64 %j) {
+; CHECK-LABEL: @ptr_eq_replace_same_underlying_object(
+; CHECK-NEXT: [[B:%.*]] = getelementptr inbounds i8, ptr [[ST:%.*]], i64 [[J:%.*]]
+; CHECK-NEXT: ret ptr [[B]]
+;
+ %a = getelementptr inbounds i8, ptr %st, i64 %i
+ %b = getelementptr inbounds i8, ptr %st, i64 %j
+ %cmp = icmp eq ptr %a, %b
+ %sel = select i1 %cmp, ptr %a, ptr %b
+ ret ptr %sel
+}
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nikic
approved these changes
Feb 10, 2025
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The test failure seems unrelated. I'm going to re-run the tests. |
…#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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@dtcxzyw (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR. |
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Backport 1af627b
Requested by: @dtcxzyw