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[InstSimplify] Add additional checks when substituting pointers #125385

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Merged
merged 3 commits into from
Feb 2, 2025
Merged

[InstSimplify] Add additional checks when substituting pointers #125385

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d09b521
[InstSimplify] Add pre-commit tests. NFC.
dtcxzyw Feb 2, 2025
e437ba2
[InstSimplify] Add additional checks when substituting pointers
dtcxzyw Feb 2, 2025
0e3837b
[InstSimplify] Add more tests. NFC.
dtcxzyw Feb 2, 2025
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17 changes: 11 additions & 6 deletions llvm/lib/Analysis/InstructionSimplify.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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"
Expand Down Expand Up @@ -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;
Expand Down
32 changes: 32 additions & 0 deletions llvm/test/Transforms/InstSimplify/select-icmp.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -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
}