[llvm] [InstCombine] Factor in op0's usages to decide leniency for one-use in foldComplexAndOrPatterns (PR #142666)
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Tue Jun 3 17:29:03 PDT 2025
https://github.com/AZero13 updated https://github.com/llvm/llvm-project/pull/142666
>From 6de915eab7f0e8f0e7c9af53a95a9f8751d2ca1f Mon Sep 17 00:00:00 2001
From: Rose <gfunni234 at gmail.com>
Date: Tue, 3 Jun 2025 16:02:02 -0400
Subject: [PATCH] [InstCombine] Factor in op0's usages to decide leniency for
one-use in foldComplexAndOrPatterns
If we can eliminate Op0 by replacing, which will happen if Op0 is one use, then we need not check if the other is one-use.
This way, we can still be sure that there is a net negative of instructions.
---
.../InstCombine/InstCombineAndOrXor.cpp | 26 +++++++++++++----
.../test/Transforms/InstCombine/and-xor-or.ll | 29 ++++++++-----------
2 files changed, 33 insertions(+), 22 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 2fb4bfecda8aa..a26aee715483e 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -2060,17 +2060,29 @@ static Instruction *foldComplexAndOrPatterns(BinaryOperator &I,
: BinaryOperator::CreateNot(Builder.CreateAnd(Xor, B));
}
+ bool Op0OneUse = Op0->hasOneUse();
+
// (~(A | B) & C) | ~(A | C) --> ~((B & C) | A)
// (~(A & B) | C) & ~(A & C) --> ~((B | C) & A)
- if (match(Op1, m_OneUse(m_Not(m_OneUse(
- m_c_BinOp(Opcode, m_Specific(A), m_Specific(C)))))))
+ if (!Op0OneUse && match(Op1, m_OneUse(m_Not(m_OneUse(m_c_BinOp(
+ Opcode, m_Specific(A), m_Specific(C)))))))
+ return BinaryOperator::CreateNot(Builder.CreateBinOp(
+ Opcode, Builder.CreateBinOp(FlippedOpcode, B, C), A));
+
+ if (Op0OneUse &&
+ match(Op1, m_Not(m_c_BinOp(Opcode, m_Specific(A), m_Specific(C)))))
return BinaryOperator::CreateNot(Builder.CreateBinOp(
Opcode, Builder.CreateBinOp(FlippedOpcode, B, C), A));
// (~(A | B) & C) | ~(B | C) --> ~((A & C) | B)
// (~(A & B) | C) & ~(B & C) --> ~((A | C) & B)
- if (match(Op1, m_OneUse(m_Not(m_OneUse(
- m_c_BinOp(Opcode, m_Specific(B), m_Specific(C)))))))
+ if (!Op0OneUse && match(Op1, m_OneUse(m_Not(m_OneUse(m_c_BinOp(
+ Opcode, m_Specific(B), m_Specific(C)))))))
+ return BinaryOperator::CreateNot(Builder.CreateBinOp(
+ Opcode, Builder.CreateBinOp(FlippedOpcode, A, C), B));
+
+ if (Op0OneUse &&
+ match(Op1, m_Not(m_c_BinOp(Opcode, m_Specific(B), m_Specific(C)))))
return BinaryOperator::CreateNot(Builder.CreateBinOp(
Opcode, Builder.CreateBinOp(FlippedOpcode, A, C), B));
@@ -2078,7 +2090,7 @@ static Instruction *foldComplexAndOrPatterns(BinaryOperator &I,
// Note, the pattern with swapped and/or is not handled because the
// result is more undefined than a source:
// (~(A & B) | C) & ~(C & (A ^ B)) --> (A ^ B ^ C) | ~(A | C) is invalid.
- if (Opcode == Instruction::Or && Op0->hasOneUse() &&
+ if (Opcode == Instruction::Or && Op0OneUse &&
match(Op1, m_OneUse(m_Not(m_CombineAnd(
m_Value(Y),
m_c_BinOp(Opcode, m_Specific(C),
@@ -2104,9 +2116,13 @@ static Instruction *foldComplexAndOrPatterns(BinaryOperator &I,
m_c_BinOp(FlippedOpcode, m_Value(C),
m_CombineAnd(m_Value(X), m_Not(m_Value(A)))),
m_Value(B))))) {
+
// X = ~A
// (~A & B & C) | ~(A | B | C) --> ~(A | (B ^ C))
// (~A | B | C) & ~(A & B & C) --> (~A | (B ^ C))
+ // TODO: One use checks are conservative. We just need to check that a total
+ // number of multiple used values does not exceed reduction
+ // in operations.
if (match(Op1, m_OneUse(m_Not(m_c_BinOp(
Opcode, m_c_BinOp(Opcode, m_Specific(A), m_Specific(B)),
m_Specific(C))))) ||
diff --git a/llvm/test/Transforms/InstCombine/and-xor-or.ll b/llvm/test/Transforms/InstCombine/and-xor-or.ll
index 8046f340a7173..1180852a7a0b5 100644
--- a/llvm/test/Transforms/InstCombine/and-xor-or.ll
+++ b/llvm/test/Transforms/InstCombine/and-xor-or.ll
@@ -1862,10 +1862,9 @@ define i32 @or_and_not_not_extra_not_use1(i32 %a, i32 %b, i32 %c) {
; CHECK-SAME: (i32 [[A:%.*]], i32 [[B:%.*]], i32 [[C:%.*]]) {
; CHECK-NEXT: [[OR1:%.*]] = or i32 [[B]], [[A]]
; CHECK-NEXT: [[NOT1:%.*]] = xor i32 [[OR1]], -1
-; CHECK-NEXT: [[OR2:%.*]] = or i32 [[A]], [[C]]
-; CHECK-NEXT: [[NOT2:%.*]] = xor i32 [[OR2]], -1
-; CHECK-NEXT: [[AND:%.*]] = and i32 [[B]], [[NOT2]]
-; CHECK-NEXT: [[OR3:%.*]] = or i32 [[AND]], [[NOT1]]
+; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[C]], [[B]]
+; CHECK-NEXT: [[TMP2:%.*]] = or i32 [[TMP1]], [[A]]
+; CHECK-NEXT: [[OR3:%.*]] = xor i32 [[TMP2]], -1
; CHECK-NEXT: call void @use(i32 [[NOT1]])
; CHECK-NEXT: ret i32 [[OR3]]
;
@@ -1926,11 +1925,9 @@ define i32 @or_and_not_not_extra_or_use1(i32 %a, i32 %b, i32 %c) {
; CHECK-LABEL: define {{[^@]+}}@or_and_not_not_extra_or_use1
; CHECK-SAME: (i32 [[A:%.*]], i32 [[B:%.*]], i32 [[C:%.*]]) {
; CHECK-NEXT: [[OR1:%.*]] = or i32 [[B]], [[A]]
-; CHECK-NEXT: [[NOT1:%.*]] = xor i32 [[OR1]], -1
-; CHECK-NEXT: [[OR2:%.*]] = or i32 [[A]], [[C]]
-; CHECK-NEXT: [[NOT2:%.*]] = xor i32 [[OR2]], -1
-; CHECK-NEXT: [[AND:%.*]] = and i32 [[B]], [[NOT2]]
-; CHECK-NEXT: [[OR3:%.*]] = or i32 [[AND]], [[NOT1]]
+; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[C]], [[B]]
+; CHECK-NEXT: [[TMP2:%.*]] = or i32 [[TMP1]], [[A]]
+; CHECK-NEXT: [[OR3:%.*]] = xor i32 [[TMP2]], -1
; CHECK-NEXT: call void @use(i32 [[OR1]])
; CHECK-NEXT: ret i32 [[OR3]]
;
@@ -2177,10 +2174,9 @@ define i32 @and_or_not_not_extra_not_use1(i32 %a, i32 %b, i32 %c) {
; CHECK-SAME: (i32 [[A:%.*]], i32 [[B:%.*]], i32 [[C:%.*]]) {
; CHECK-NEXT: [[AND1:%.*]] = and i32 [[B]], [[A]]
; CHECK-NEXT: [[NOT1:%.*]] = xor i32 [[AND1]], -1
-; CHECK-NEXT: [[AND2:%.*]] = and i32 [[A]], [[C]]
-; CHECK-NEXT: [[NOT2:%.*]] = xor i32 [[AND2]], -1
-; CHECK-NEXT: [[OR:%.*]] = or i32 [[B]], [[NOT2]]
-; CHECK-NEXT: [[AND3:%.*]] = xor i32 [[AND1]], [[OR]]
+; CHECK-NEXT: [[TMP1:%.*]] = or i32 [[C]], [[B]]
+; CHECK-NEXT: [[TMP2:%.*]] = and i32 [[TMP1]], [[A]]
+; CHECK-NEXT: [[AND3:%.*]] = xor i32 [[TMP2]], -1
; CHECK-NEXT: call void @use(i32 [[NOT1]])
; CHECK-NEXT: ret i32 [[AND3]]
;
@@ -2241,10 +2237,9 @@ define i32 @and_or_not_not_extra_or_use1(i32 %a, i32 %b, i32 %c) {
; CHECK-LABEL: define {{[^@]+}}@and_or_not_not_extra_or_use1
; CHECK-SAME: (i32 [[A:%.*]], i32 [[B:%.*]], i32 [[C:%.*]]) {
; CHECK-NEXT: [[AND1:%.*]] = and i32 [[B]], [[A]]
-; CHECK-NEXT: [[AND2:%.*]] = and i32 [[A]], [[C]]
-; CHECK-NEXT: [[NOT2:%.*]] = xor i32 [[AND2]], -1
-; CHECK-NEXT: [[OR:%.*]] = or i32 [[B]], [[NOT2]]
-; CHECK-NEXT: [[AND3:%.*]] = xor i32 [[AND1]], [[OR]]
+; CHECK-NEXT: [[TMP1:%.*]] = or i32 [[C]], [[B]]
+; CHECK-NEXT: [[TMP2:%.*]] = and i32 [[TMP1]], [[A]]
+; CHECK-NEXT: [[AND3:%.*]] = xor i32 [[TMP2]], -1
; CHECK-NEXT: call void @use(i32 [[AND1]])
; CHECK-NEXT: ret i32 [[AND3]]
;
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