[llvm] [InstCombine] Fold Xor with or disjoint (PR #105992)
Amr Hesham via llvm-commits
llvm-commits at lists.llvm.org
Sun Aug 25 08:58:43 PDT 2024
https://github.com/AmrDeveloper created https://github.com/llvm/llvm-project/pull/105992
Implement a missing optimization fold from ((select C1, C2) | A) ^ C3) to be ((Select C1 ^ C3, C2 ^ C3) | A)
Fixes: #79266
>From b8a3d12d87f67960edab043a0394b63b5eb4b312 Mon Sep 17 00:00:00 2001
From: AmrDeveloper <amr96 at programmer.net>
Date: Sun, 25 Aug 2024 16:56:47 +0200
Subject: [PATCH 1/2] [InstCombine] Add pre-commit tests
---
.../Transforms/InstCombine/disjoint_or.ll | 34 +++++++++++++++++++
1 file changed, 34 insertions(+)
create mode 100644 llvm/test/Transforms/InstCombine/disjoint_or.ll
diff --git a/llvm/test/Transforms/InstCombine/disjoint_or.ll b/llvm/test/Transforms/InstCombine/disjoint_or.ll
new file mode 100644
index 00000000000000..b873cc575eef62
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/disjoint_or.ll
@@ -0,0 +1,34 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+define i32 @fold_xor_with_disjoint_or(i32 %a, i1 %c) {
+; CHECK-LABEL: define i32 @fold_xor_with_disjoint_or(
+; CHECK-SAME: i32 [[A:%.*]], i1 [[C:%.*]]) {
+; CHECK-NEXT: [[S:%.*]] = select i1 [[C]], i32 0, i32 4
+; CHECK-NEXT: [[SHL:%.*]] = shl i32 [[A]], 4
+; CHECK-NEXT: [[OR:%.*]] = or disjoint i32 [[S]], [[SHL]]
+; CHECK-NEXT: [[XOR:%.*]] = xor i32 [[OR]], 4
+; CHECK-NEXT: ret i32 [[XOR]]
+;
+ %s = select i1 %c, i32 0, i32 4
+ %shl = shl i32 %a, 4
+ %or = or disjoint i32 %s, %shl
+ %xor = xor i32 %or, 4
+ ret i32 %xor
+}
+
+define <2 x i32> @fold_xor_with_disjoint_or_vec(<2 x i32> %a, i1 %c) {
+; CHECK-LABEL: define <2 x i32> @fold_xor_with_disjoint_or_vec(
+; CHECK-SAME: <2 x i32> [[A:%.*]], i1 [[C:%.*]]) {
+; CHECK-NEXT: [[S:%.*]] = select i1 [[C]], <2 x i32> zeroinitializer, <2 x i32> <i32 4, i32 4>
+; CHECK-NEXT: [[SHL:%.*]] = shl <2 x i32> [[A]], <i32 4, i32 4>
+; CHECK-NEXT: [[OR:%.*]] = or disjoint <2 x i32> [[S]], [[SHL]]
+; CHECK-NEXT: [[XOR:%.*]] = xor <2 x i32> [[OR]], <i32 4, i32 4>
+; CHECK-NEXT: ret <2 x i32> [[XOR]]
+;
+ %s = select i1 %c, <2 x i32> <i32 0, i32 0>, <2 x i32> <i32 4, i32 4>
+ %shl = shl <2 x i32> %a, <i32 4, i32 4>
+ %or = or disjoint <2 x i32> %s, %shl
+ %xor = xor <2 x i32> %or, <i32 4, i32 4>
+ ret <2 x i32> %xor
+}
>From 7c579c805f21eb0a08768f0dd742968d9513c6db Mon Sep 17 00:00:00 2001
From: AmrDeveloper <amr96 at programmer.net>
Date: Sun, 25 Aug 2024 17:01:19 +0200
Subject: [PATCH 2/2] [InstCombine] Fold Xor with or disjoint
Implement a missing optimization fold from ((select C1, C2) | A) ^ C3)
to be ((Select C1 ^ C3, C2 ^ C3) | A)
---
.../InstCombine/InstCombineAndOrXor.cpp | 22 +++++++++++++++++++
.../Transforms/InstCombine/disjoint_or.ll | 10 ++++-----
2 files changed, 26 insertions(+), 6 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index b703bc7d04db58..59bd133e56b118 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -4056,6 +4056,25 @@ Instruction *InstCombinerImpl::visitOr(BinaryOperator &I) {
return nullptr;
}
+static Instruction *foldXorToOr(BinaryOperator &I,
+ InstCombiner::BuilderTy &Builder) {
+ assert(I.getOpcode() == Instruction::Xor);
+ Value *A, *B, *C, *D, *E;
+
+ // ((select C, A, B) | E) ^ D) -> (select C, A ^ D, B ^ D) | E)
+ if (match(&I,
+ m_c_Xor(m_c_DisjointOr(m_Select(m_Value(C), m_Value(A), m_Value(B)),
+ m_Value(E)),
+ m_Value(D)))) {
+ Value *XorAB = Builder.CreateXor(A, D);
+ Value *XorBD = Builder.CreateXor(B, D);
+ Value *S = Builder.CreateSelect(C, XorAB, XorBD);
+ return BinaryOperator::CreateDisjointOr(S, E);
+ }
+
+ return nullptr;
+}
+
/// A ^ B can be specified using other logic ops in a variety of patterns. We
/// can fold these early and efficiently by morphing an existing instruction.
static Instruction *foldXorToXor(BinaryOperator &I,
@@ -4658,6 +4677,9 @@ Instruction *InstCombinerImpl::visitXor(BinaryOperator &I) {
if (Instruction *NewXor = foldXorToXor(I, Builder))
return NewXor;
+ if (Instruction *NewOr = foldXorToOr(I, Builder))
+ return NewOr;
+
// (A&B)^(A&C) -> A&(B^C) etc
if (Value *V = foldUsingDistributiveLaws(I))
return replaceInstUsesWith(I, V);
diff --git a/llvm/test/Transforms/InstCombine/disjoint_or.ll b/llvm/test/Transforms/InstCombine/disjoint_or.ll
index b873cc575eef62..81fa4c33199fd4 100644
--- a/llvm/test/Transforms/InstCombine/disjoint_or.ll
+++ b/llvm/test/Transforms/InstCombine/disjoint_or.ll
@@ -4,10 +4,9 @@
define i32 @fold_xor_with_disjoint_or(i32 %a, i1 %c) {
; CHECK-LABEL: define i32 @fold_xor_with_disjoint_or(
; CHECK-SAME: i32 [[A:%.*]], i1 [[C:%.*]]) {
-; CHECK-NEXT: [[S:%.*]] = select i1 [[C]], i32 0, i32 4
; CHECK-NEXT: [[SHL:%.*]] = shl i32 [[A]], 4
-; CHECK-NEXT: [[OR:%.*]] = or disjoint i32 [[S]], [[SHL]]
-; CHECK-NEXT: [[XOR:%.*]] = xor i32 [[OR]], 4
+; CHECK-NEXT: [[TMP1:%.*]] = select i1 [[C]], i32 4, i32 0
+; CHECK-NEXT: [[XOR:%.*]] = or disjoint i32 [[TMP1]], [[SHL]]
; CHECK-NEXT: ret i32 [[XOR]]
;
%s = select i1 %c, i32 0, i32 4
@@ -20,10 +19,9 @@ define i32 @fold_xor_with_disjoint_or(i32 %a, i1 %c) {
define <2 x i32> @fold_xor_with_disjoint_or_vec(<2 x i32> %a, i1 %c) {
; CHECK-LABEL: define <2 x i32> @fold_xor_with_disjoint_or_vec(
; CHECK-SAME: <2 x i32> [[A:%.*]], i1 [[C:%.*]]) {
-; CHECK-NEXT: [[S:%.*]] = select i1 [[C]], <2 x i32> zeroinitializer, <2 x i32> <i32 4, i32 4>
; CHECK-NEXT: [[SHL:%.*]] = shl <2 x i32> [[A]], <i32 4, i32 4>
-; CHECK-NEXT: [[OR:%.*]] = or disjoint <2 x i32> [[S]], [[SHL]]
-; CHECK-NEXT: [[XOR:%.*]] = xor <2 x i32> [[OR]], <i32 4, i32 4>
+; CHECK-NEXT: [[TMP1:%.*]] = select i1 [[C]], <2 x i32> <i32 4, i32 4>, <2 x i32> zeroinitializer
+; CHECK-NEXT: [[XOR:%.*]] = or disjoint <2 x i32> [[TMP1]], [[SHL]]
; CHECK-NEXT: ret <2 x i32> [[XOR]]
;
%s = select i1 %c, <2 x i32> <i32 0, i32 0>, <2 x i32> <i32 4, i32 4>
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