[InstCombine] Fold xor of icmps using range information #76334
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@llvm/pr-subscribers-llvm-transforms Author: Yingwei Zheng (dtcxzyw) ChangesThis patch folds xor of icmps into a single comparison using range-based reasoning as It is an alternative to #75609. Full diff: https://github.com/llvm/llvm-project/pull/76334.diff 3 Files Affected:
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 5e362f4117d051..63b1e0f64a8824 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -3956,35 +3956,50 @@ Value *InstCombinerImpl::foldXorOfICmps(ICmpInst *LHS, ICmpInst *RHS,
const APInt *LC, *RC;
if (match(LHS1, m_APInt(LC)) && match(RHS1, m_APInt(RC)) &&
LHS0->getType() == RHS0->getType() &&
- LHS0->getType()->isIntOrIntVectorTy() &&
- (LHS->hasOneUse() || RHS->hasOneUse())) {
+ LHS0->getType()->isIntOrIntVectorTy()) {
// Convert xor of signbit tests to signbit test of xor'd values:
// (X > -1) ^ (Y > -1) --> (X ^ Y) < 0
// (X < 0) ^ (Y < 0) --> (X ^ Y) < 0
// (X > -1) ^ (Y < 0) --> (X ^ Y) > -1
// (X < 0) ^ (Y > -1) --> (X ^ Y) > -1
bool TrueIfSignedL, TrueIfSignedR;
- if (isSignBitCheck(PredL, *LC, TrueIfSignedL) &&
+ if ((LHS->hasOneUse() || RHS->hasOneUse()) &&
+ isSignBitCheck(PredL, *LC, TrueIfSignedL) &&
isSignBitCheck(PredR, *RC, TrueIfSignedR)) {
Value *XorLR = Builder.CreateXor(LHS0, RHS0);
return TrueIfSignedL == TrueIfSignedR ? Builder.CreateIsNeg(XorLR) :
Builder.CreateIsNotNeg(XorLR);
}
- // (X > C) ^ (X < C + 2) --> X != C + 1
- // (X < C + 2) ^ (X > C) --> X != C + 1
- // Considering the correctness of this pattern, we should avoid that C is
- // non-negative and C + 2 is negative, although it will be matched by other
- // patterns.
- const APInt *C1, *C2;
- if ((PredL == CmpInst::ICMP_SGT && match(LHS1, m_APInt(C1)) &&
- PredR == CmpInst::ICMP_SLT && match(RHS1, m_APInt(C2))) ||
- (PredL == CmpInst::ICMP_SLT && match(LHS1, m_APInt(C2)) &&
- PredR == CmpInst::ICMP_SGT && match(RHS1, m_APInt(C1))))
- if (LHS0 == RHS0 && *C1 + 2 == *C2 &&
- (C1->isNegative() || C2->isNonNegative()))
- return Builder.CreateICmpNE(LHS0,
- ConstantInt::get(LHS0->getType(), *C1 + 1));
+ // Fold (icmp pred1 X, C1) ^ (icmp pred2 X, C2)
+ // into a single comparison using range-based reasoning.
+ if (LHS0 == RHS0) {
+ ConstantRange CR1 = ConstantRange::makeExactICmpRegion(PredL, *LC);
+ ConstantRange CR2 = ConstantRange::makeExactICmpRegion(PredR, *RC);
+ auto CRUnion = CR1.exactUnionWith(CR2);
+ auto CRIntersect = CR1.exactIntersectWith(CR2);
+ if (CRUnion && CRIntersect)
+ if (auto CR = CRUnion->exactIntersectWith(CRIntersect->inverse())) {
+ if (CR->isFullSet())
+ return ConstantInt::getTrue(I.getType());
+ if (CR->isEmptySet())
+ return ConstantInt::getFalse(I.getType());
+
+ CmpInst::Predicate NewPred;
+ APInt NewC, Offset;
+ CR->getEquivalentICmp(NewPred, NewC, Offset);
+
+ if ((Offset.isZero() && (LHS->hasOneUse() || RHS->hasOneUse())) ||
+ (LHS->hasOneUse() && RHS->hasOneUse())) {
+ Value *NewV = LHS0;
+ Type *Ty = LHS0->getType();
+ if (!Offset.isZero())
+ NewV = Builder.CreateAdd(NewV, ConstantInt::get(Ty, Offset));
+ return Builder.CreateICmp(NewPred, NewV,
+ ConstantInt::get(Ty, NewC));
+ }
+ }
+ }
}
// Instead of trying to imitate the folds for and/or, decompose this 'xor'
diff --git a/llvm/test/Transforms/InstCombine/and-or-icmps.ll b/llvm/test/Transforms/InstCombine/and-or-icmps.ll
index 881a9b7ff129db..91ecf24760259b 100644
--- a/llvm/test/Transforms/InstCombine/and-or-icmps.ll
+++ b/llvm/test/Transforms/InstCombine/and-or-icmps.ll
@@ -3015,10 +3015,8 @@ define i32 @icmp_x_slt_0_and_icmp_y_sgt_neg1_i32_fail(i32 %x, i32 %y) {
define i32 @icmp_slt_0_xor_icmp_sge_neg2_i32_fail(i32 %x) {
; CHECK-LABEL: @icmp_slt_0_xor_icmp_sge_neg2_i32_fail(
-; CHECK-NEXT: [[A:%.*]] = icmp sgt i32 [[X:%.*]], -3
-; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 [[X]], 0
-; CHECK-NEXT: [[TMP2:%.*]] = xor i1 [[TMP1]], [[A]]
-; CHECK-NEXT: [[D:%.*]] = zext i1 [[TMP2]] to i32
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i32 [[X:%.*]], -2
+; CHECK-NEXT: [[D:%.*]] = zext i1 [[TMP1]] to i32
; CHECK-NEXT: ret i32 [[D]]
;
%A = icmp sge i32 %x, -2
diff --git a/llvm/test/Transforms/InstCombine/xor-icmps.ll b/llvm/test/Transforms/InstCombine/xor-icmps.ll
index c85993ea9a7e0d..f104cd7fdcada5 100644
--- a/llvm/test/Transforms/InstCombine/xor-icmps.ll
+++ b/llvm/test/Transforms/InstCombine/xor-icmps.ll
@@ -171,3 +171,151 @@ define i1 @xor_icmp_ptr(ptr %c, ptr %d) {
ret i1 %xor
}
+; Tests from PR70928
+define i1 @xor_icmp_true_signed(i32 %a) {
+; CHECK-LABEL: @xor_icmp_true_signed(
+; CHECK-NEXT: ret i1 true
+;
+ %cmp = icmp sgt i32 %a, 5
+ %cmp1 = icmp slt i32 %a, 6
+ %cmp3 = xor i1 %cmp, %cmp1
+ ret i1 %cmp3
+}
+define i1 @xor_icmp_true_signed_multiuse1(i32 %a) {
+; CHECK-LABEL: @xor_icmp_true_signed_multiuse1(
+; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[A:%.*]], 5
+; CHECK-NEXT: call void @use(i1 [[CMP]])
+; CHECK-NEXT: ret i1 true
+;
+ %cmp = icmp sgt i32 %a, 5
+ call void @use(i1 %cmp)
+ %cmp1 = icmp slt i32 %a, 6
+ %cmp3 = xor i1 %cmp, %cmp1
+ ret i1 %cmp3
+}
+define i1 @xor_icmp_true_signed_multiuse2(i32 %a) {
+; CHECK-LABEL: @xor_icmp_true_signed_multiuse2(
+; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[A:%.*]], 5
+; CHECK-NEXT: call void @use(i1 [[CMP]])
+; CHECK-NEXT: [[CMP1:%.*]] = icmp slt i32 [[A]], 6
+; CHECK-NEXT: call void @use(i1 [[CMP1]])
+; CHECK-NEXT: ret i1 true
+;
+ %cmp = icmp sgt i32 %a, 5
+ call void @use(i1 %cmp)
+ %cmp1 = icmp slt i32 %a, 6
+ call void @use(i1 %cmp1)
+ %cmp3 = xor i1 %cmp, %cmp1
+ ret i1 %cmp3
+}
+define i1 @xor_icmp_true_signed_commuted(i32 %a) {
+; CHECK-LABEL: @xor_icmp_true_signed_commuted(
+; CHECK-NEXT: ret i1 true
+;
+ %cmp = icmp sgt i32 %a, 5
+ %cmp1 = icmp slt i32 %a, 6
+ %cmp3 = xor i1 %cmp1, %cmp
+ ret i1 %cmp3
+}
+define i1 @xor_icmp_true_unsigned(i32 %a) {
+; CHECK-LABEL: @xor_icmp_true_unsigned(
+; CHECK-NEXT: ret i1 true
+;
+ %cmp = icmp ugt i32 %a, 5
+ %cmp1 = icmp ult i32 %a, 6
+ %cmp3 = xor i1 %cmp, %cmp1
+ ret i1 %cmp3
+}
+define i1 @xor_icmp_to_ne(i32 %a) {
+; CHECK-LABEL: @xor_icmp_to_ne(
+; CHECK-NEXT: [[CMP3:%.*]] = icmp ne i32 [[A:%.*]], 5
+; CHECK-NEXT: ret i1 [[CMP3]]
+;
+ %cmp = icmp sgt i32 %a, 4
+ %cmp1 = icmp slt i32 %a, 6
+ %cmp3 = xor i1 %cmp, %cmp1
+ ret i1 %cmp3
+}
+define i1 @xor_icmp_to_ne_multiuse1(i32 %a) {
+; CHECK-LABEL: @xor_icmp_to_ne_multiuse1(
+; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[A:%.*]], 4
+; CHECK-NEXT: call void @use(i1 [[CMP]])
+; CHECK-NEXT: [[CMP3:%.*]] = icmp ne i32 [[A]], 5
+; CHECK-NEXT: ret i1 [[CMP3]]
+;
+ %cmp = icmp sgt i32 %a, 4
+ call void @use(i1 %cmp)
+ %cmp1 = icmp slt i32 %a, 6
+ %cmp3 = xor i1 %cmp, %cmp1
+ ret i1 %cmp3
+}
+define i1 @xor_icmp_to_icmp_add(i32 %a) {
+; CHECK-LABEL: @xor_icmp_to_icmp_add(
+; CHECK-NEXT: [[TMP1:%.*]] = add i32 [[A:%.*]], -6
+; CHECK-NEXT: [[CMP3:%.*]] = icmp ult i32 [[TMP1]], -2
+; CHECK-NEXT: ret i1 [[CMP3]]
+;
+ %cmp = icmp sgt i32 %a, 3
+ %cmp1 = icmp slt i32 %a, 6
+ %cmp3 = xor i1 %cmp, %cmp1
+ ret i1 %cmp3
+}
+; Negative tests
+; The result of ConstantRange::difference is not exact.
+define i1 @xor_icmp_invalid_range(i8 %x0) {
+; CHECK-LABEL: @xor_icmp_invalid_range(
+; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X0:%.*]], -5
+; CHECK-NEXT: [[OR_COND:%.*]] = icmp ne i8 [[TMP1]], 0
+; CHECK-NEXT: ret i1 [[OR_COND]]
+;
+ %cmp = icmp eq i8 %x0, 0
+ %cmp4 = icmp ne i8 %x0, 4
+ %or.cond = xor i1 %cmp, %cmp4
+ ret i1 %or.cond
+}
+define i1 @xor_icmp_to_ne_multiuse2(i32 %a) {
+; CHECK-LABEL: @xor_icmp_to_ne_multiuse2(
+; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[A:%.*]], 4
+; CHECK-NEXT: call void @use(i1 [[CMP]])
+; CHECK-NEXT: [[CMP1:%.*]] = icmp slt i32 [[A]], 6
+; CHECK-NEXT: call void @use(i1 [[CMP1]])
+; CHECK-NEXT: [[CMP3:%.*]] = xor i1 [[CMP]], [[CMP1]]
+; CHECK-NEXT: ret i1 [[CMP3]]
+;
+ %cmp = icmp sgt i32 %a, 4
+ call void @use(i1 %cmp)
+ %cmp1 = icmp slt i32 %a, 6
+ call void @use(i1 %cmp1)
+ %cmp3 = xor i1 %cmp, %cmp1
+ ret i1 %cmp3
+}
+define i1 @xor_icmp_to_icmp_add_multiuse1(i32 %a) {
+; CHECK-LABEL: @xor_icmp_to_icmp_add_multiuse1(
+; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[A:%.*]], 3
+; CHECK-NEXT: call void @use(i1 [[CMP]])
+; CHECK-NEXT: [[CMP1:%.*]] = icmp slt i32 [[A]], 6
+; CHECK-NEXT: [[CMP3:%.*]] = xor i1 [[CMP]], [[CMP1]]
+; CHECK-NEXT: ret i1 [[CMP3]]
+;
+ %cmp = icmp sgt i32 %a, 3
+ call void @use(i1 %cmp)
+ %cmp1 = icmp slt i32 %a, 6
+ %cmp3 = xor i1 %cmp, %cmp1
+ ret i1 %cmp3
+}
+define i1 @xor_icmp_to_icmp_add_multiuse2(i32 %a) {
+; CHECK-LABEL: @xor_icmp_to_icmp_add_multiuse2(
+; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[A:%.*]], 3
+; CHECK-NEXT: call void @use(i1 [[CMP]])
+; CHECK-NEXT: [[CMP1:%.*]] = icmp slt i32 [[A]], 6
+; CHECK-NEXT: call void @use(i1 [[CMP1]])
+; CHECK-NEXT: [[CMP3:%.*]] = xor i1 [[CMP]], [[CMP1]]
+; CHECK-NEXT: ret i1 [[CMP3]]
+;
+ %cmp = icmp sgt i32 %a, 3
+ call void @use(i1 %cmp)
+ %cmp1 = icmp slt i32 %a, 6
+ call void @use(i1 %cmp1)
+ %cmp3 = xor i1 %cmp, %cmp1
+ ret i1 %cmp3
+}
|
dtcxzyw
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This patch folds xor of icmps into a single comparison using range-based reasoning as
foldAndOrOfICmpsUsingRangesdoes.Fixes #70928.
It is an alternative to #75609.