[llvm] Revert "[InstCombine] Support gep nuw in icmp folds" (PR #118698)
via llvm-commits
llvm-commits at lists.llvm.org
Wed Dec 4 12:51:20 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: Vitaly Buka (vitalybuka)
<details>
<summary>Changes</summary>
Reverts llvm/llvm-project#<!-- -->118472
---
Full diff: https://github.com/llvm/llvm-project/pull/118698.diff
2 Files Affected:
- (modified) llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp (+9-27)
- (modified) llvm/test/Transforms/InstCombine/icmp-gep.ll (-75)
``````````diff
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index b486c5b0b6fad0..56391d320e8b37 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -689,32 +689,13 @@ Instruction *InstCombinerImpl::foldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
if (!isa<GetElementPtrInst>(RHS))
RHS = RHS->stripPointerCasts();
- auto CanFold = [Cond](GEPNoWrapFlags NW) {
- if (ICmpInst::isEquality(Cond))
- return true;
-
- // Unsigned predicates can be folded if the GEPs have *any* nowrap flags.
- assert(ICmpInst::isUnsigned(Cond));
- return NW != GEPNoWrapFlags::none();
- };
-
- auto NewICmp = [Cond](GEPNoWrapFlags NW, Value *Op1, Value *Op2) {
- if (!NW.hasNoUnsignedWrap()) {
- // Convert signed to unsigned comparison.
- return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Op1, Op2);
- }
-
- auto *I = new ICmpInst(Cond, Op1, Op2);
- I->setSameSign(NW.hasNoUnsignedSignedWrap());
- return I;
- };
-
Value *PtrBase = GEPLHS->getOperand(0);
- if (PtrBase == RHS && CanFold(GEPLHS->getNoWrapFlags())) {
+ if (PtrBase == RHS &&
+ (GEPLHS->hasNoUnsignedSignedWrap() || ICmpInst::isEquality(Cond))) {
// ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
Value *Offset = EmitGEPOffset(GEPLHS);
- return NewICmp(GEPLHS->getNoWrapFlags(), Offset,
- Constant::getNullValue(Offset->getType()));
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
+ Constant::getNullValue(Offset->getType()));
}
if (GEPLHS->isInBounds() && ICmpInst::isEquality(Cond) &&
@@ -832,18 +813,19 @@ Instruction *InstCombinerImpl::foldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
return replaceInstUsesWith(I, // No comparison is needed here.
ConstantInt::get(I.getType(), ICmpInst::isTrueWhenEqual(Cond)));
- else if (NumDifferences == 1 && CanFold(NW)) {
+ else if (NumDifferences == 1 && NW.hasNoUnsignedSignedWrap()) {
Value *LHSV = GEPLHS->getOperand(DiffOperand);
Value *RHSV = GEPRHS->getOperand(DiffOperand);
- return NewICmp(NW, LHSV, RHSV);
+ // Make sure we do a signed comparison here.
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
}
}
- if (CanFold(NW)) {
+ if (NW.hasNoUnsignedSignedWrap() || CmpInst::isEquality(Cond)) {
// ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
Value *L = EmitGEPOffset(GEPLHS, /*RewriteGEP=*/true);
Value *R = EmitGEPOffset(GEPRHS, /*RewriteGEP=*/true);
- return NewICmp(NW, L, R);
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
}
}
diff --git a/llvm/test/Transforms/InstCombine/icmp-gep.ll b/llvm/test/Transforms/InstCombine/icmp-gep.ll
index 1bc000cd6ebf1e..1545d034b2ac31 100644
--- a/llvm/test/Transforms/InstCombine/icmp-gep.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-gep.ll
@@ -143,44 +143,6 @@ define i1 @ult_base_nusw(ptr %x, i64 %y) {
ret i1 %r
}
-define i1 @ugt_base_nuw(ptr %x, i64 %y) {
-; CHECK-LABEL: @ugt_base_nuw(
-; CHECK-NEXT: [[R:%.*]] = icmp ne i64 [[Y:%.*]], 0
-; CHECK-NEXT: ret i1 [[R]]
-;
- %g = getelementptr nuw i8, ptr %x, i64 %y
- %r = icmp ugt ptr %g, %x
- ret i1 %r
-}
-
-define i1 @ugt_base_nusw_nuw(ptr %x, i64 %y) {
-; CHECK-LABEL: @ugt_base_nusw_nuw(
-; CHECK-NEXT: [[R:%.*]] = icmp ne i64 [[Y:%.*]], 0
-; CHECK-NEXT: ret i1 [[R]]
-;
- %g = getelementptr nusw nuw i8, ptr %x, i64 %y
- %r = icmp ugt ptr %g, %x
- ret i1 %r
-}
-
-define i1 @uge_base_nuw(ptr %x, i64 %y) {
-; CHECK-LABEL: @uge_base_nuw(
-; CHECK-NEXT: ret i1 true
-;
- %g = getelementptr nuw i8, ptr %x, i64 %y
- %r = icmp uge ptr %g, %x
- ret i1 %r
-}
-
-define i1 @uge_base_nusw_nuw(ptr %x, i64 %y) {
-; CHECK-LABEL: @uge_base_nusw_nuw(
-; CHECK-NEXT: ret i1 true
-;
- %g = getelementptr nusw nuw i8, ptr %x, i64 %y
- %r = icmp uge ptr %g, %x
- ret i1 %r
-}
-
define i1 @ugt_base_inbounds_commute(i64 %y) {
; CHECK-LABEL: @ugt_base_inbounds_commute(
; CHECK-NEXT: [[X:%.*]] = call ptr @getptr()
@@ -357,43 +319,6 @@ define i1 @test60_nusw_inbounds(ptr %foo, i64 %i, i64 %j) {
ret i1 %cmp
}
-define i1 @test60_nuw(ptr %foo, i64 %i, i64 %j) {
-; CHECK-LABEL: @test60_nuw(
-; CHECK-NEXT: [[GEP1_IDX:%.*]] = shl nuw i64 [[I:%.*]], 2
-; CHECK-NEXT: [[CMP:%.*]] = icmp ult i64 [[GEP1_IDX]], [[J:%.*]]
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %gep1 = getelementptr nuw i32, ptr %foo, i64 %i
- %gep2 = getelementptr nuw i8, ptr %foo, i64 %j
- %cmp = icmp ult ptr %gep1, %gep2
- ret i1 %cmp
-}
-
-define i1 @test60_nusw_nuw(ptr %foo, i64 %i, i64 %j) {
-; CHECK-LABEL: @test60_nusw_nuw(
-; CHECK-NEXT: [[GEP1_IDX:%.*]] = shl nuw nsw i64 [[I:%.*]], 2
-; CHECK-NEXT: [[CMP:%.*]] = icmp samesign ult i64 [[GEP1_IDX]], [[J:%.*]]
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %gep1 = getelementptr nusw nuw i32, ptr %foo, i64 %i
- %gep2 = getelementptr nusw nuw i8, ptr %foo, i64 %j
- %cmp = icmp ult ptr %gep1, %gep2
- ret i1 %cmp
-}
-
-define i1 @test60_nusw_nuw_mix(ptr %foo, i64 %i, i64 %j) {
-; CHECK-LABEL: @test60_nusw_nuw_mix(
-; CHECK-NEXT: [[GEP1:%.*]] = getelementptr nuw i32, ptr [[FOO:%.*]], i64 [[I:%.*]]
-; CHECK-NEXT: [[GEP2:%.*]] = getelementptr nusw i8, ptr [[FOO]], i64 [[J:%.*]]
-; CHECK-NEXT: [[CMP:%.*]] = icmp ult ptr [[GEP1]], [[GEP2]]
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %gep1 = getelementptr nuw i32, ptr %foo, i64 %i
- %gep2 = getelementptr nusw i8, ptr %foo, i64 %j
- %cmp = icmp ult ptr %gep1, %gep2
- ret i1 %cmp
-}
-
define i1 @test_gep_ult_no_inbounds(ptr %foo, i64 %i, i64 %j) {
; CHECK-LABEL: @test_gep_ult_no_inbounds(
; CHECK-NEXT: [[GEP1:%.*]] = getelementptr i32, ptr [[FOO:%.*]], i64 [[I:%.*]]
``````````
</details>
https://github.com/llvm/llvm-project/pull/118698
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