[llvm] [InstCombine] Canonicalize `icmp ult (add X, C2), C` expressions (PR #95649)
Antonio Frighetto via llvm-commits
llvm-commits at lists.llvm.org
Sun Jun 16 01:57:57 PDT 2024
https://github.com/antoniofrighetto updated https://github.com/llvm/llvm-project/pull/95649
>From 7a49a0f23aaaae7c6134a7ada7c29c36bdee4dc6 Mon Sep 17 00:00:00 2001
From: Antonio Frighetto <me at antoniofrighetto.com>
Date: Sat, 15 Jun 2024 10:45:32 +0200
Subject: [PATCH 1/3] [InstCombine] Precommit tests for PR95649 (NFC)
---
llvm/test/Transforms/InstCombine/icmp-add.ll | 65 ++++++++++++++++++++
1 file changed, 65 insertions(+)
diff --git a/llvm/test/Transforms/InstCombine/icmp-add.ll b/llvm/test/Transforms/InstCombine/icmp-add.ll
index 6b4e5a5372c52..84bd3c3d79020 100644
--- a/llvm/test/Transforms/InstCombine/icmp-add.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-add.ll
@@ -3023,4 +3023,69 @@ define i1 @icmp_addnuw_nonzero_fail_multiuse(i32 %x, i32 %y) {
ret i1 %c
}
+define i1 @ult_add_C2_pow2_C_neg(i8 %x) {
+; CHECK-LABEL: @ult_add_C2_pow2_C_neg(
+; CHECK-NEXT: [[I:%.*]] = add i8 [[X:%.*]], 32
+; CHECK-NEXT: [[C:%.*]] = icmp ult i8 [[I]], -32
+; CHECK-NEXT: ret i1 [[C]]
+;
+ %i = add i8 %x, 32
+ %c = icmp ult i8 %i, -32
+ ret i1 %c
+}
+
+define i1 @ult_add_nsw_C2_pow2_C_neg(i8 %x) {
+; CHECK-LABEL: @ult_add_nsw_C2_pow2_C_neg(
+; CHECK-NEXT: [[I:%.*]] = add nsw i8 [[X:%.*]], 32
+; CHECK-NEXT: [[C:%.*]] = icmp ult i8 [[I]], -32
+; CHECK-NEXT: ret i1 [[C]]
+;
+ %i = add nsw i8 %x, 32
+ %c = icmp ult i8 %i, -32
+ ret i1 %c
+}
+
+define i1 @ult_add_nuw_nsw_C2_pow2_C_neg(i8 %x) {
+; CHECK-LABEL: @ult_add_nuw_nsw_C2_pow2_C_neg(
+; CHECK-NEXT: [[C:%.*]] = icmp ult i8 [[X:%.*]], -64
+; CHECK-NEXT: ret i1 [[C]]
+;
+ %i = add nuw nsw i8 %x, 32
+ %c = icmp ult i8 %i, -32
+ ret i1 %c
+}
+
+define i1 @ult_add_C2_neg_C_pow2(i8 %x) {
+; CHECK-LABEL: @ult_add_C2_neg_C_pow2(
+; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X:%.*]], -32
+; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[TMP1]], 32
+; CHECK-NEXT: ret i1 [[C]]
+;
+ %i = add i8 %x, -32
+ %c = icmp ult i8 %i, 32
+ ret i1 %c
+}
+
+define <2 x i1> @ult_add_C2_pow2_C_neg_vec(<2 x i8> %x) {
+; CHECK-LABEL: @ult_add_C2_pow2_C_neg_vec(
+; CHECK-NEXT: [[I:%.*]] = add <2 x i8> [[X:%.*]], <i8 32, i8 32>
+; CHECK-NEXT: [[C:%.*]] = icmp ult <2 x i8> [[I]], <i8 -32, i8 -32>
+; CHECK-NEXT: ret <2 x i1> [[C]]
+;
+ %i = add <2 x i8> %x, <i8 32, i8 32>
+ %c = icmp ult <2 x i8> %i, <i8 -32, i8 -32>
+ ret <2 x i1> %c
+}
+
+define i1 @uge_add_C2_pow2_C_neg(i8 %x) {
+; CHECK-LABEL: @uge_add_C2_pow2_C_neg(
+; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X:%.*]], -32
+; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[TMP1]], -64
+; CHECK-NEXT: ret i1 [[C]]
+;
+ %i = add i8 %x, 32
+ %c = icmp uge i8 %i, -32
+ ret i1 %c
+}
+
declare void @llvm.assume(i1)
>From f4ff5cc28a07879b8f999149cadc691415253309 Mon Sep 17 00:00:00 2001
From: Antonio Frighetto <me at antoniofrighetto.com>
Date: Sat, 15 Jun 2024 10:45:59 +0200
Subject: [PATCH 2/3] [InstCombine] Canonicalize `icmp ult (add X, C2), C`
pattern
`icmp ult (add X, C2), C` can be folded to `icmp ne (and X, C), 2C`,
subject to `C == -C2` and C2 being a power of 2.
Proofs: https://alive2.llvm.org/ce/z/P-VVmQ.
---
.../Transforms/InstCombine/InstCombineCompares.cpp | 7 +++++++
llvm/test/Transforms/InstCombine/icmp-add.ll | 12 ++++++------
2 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 34b0f8b860497..51dd3384c1fb5 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3130,6 +3130,13 @@ Instruction *InstCombinerImpl::foldICmpAddConstant(ICmpInst &Cmp,
return new ICmpInst(ICmpInst::ICMP_EQ, Builder.CreateAnd(X, -C),
ConstantExpr::getNeg(cast<Constant>(Y)));
+ // X+C2 <u C -> (X & C) == 2C
+ // iff C == -(C2)
+ // C2 is a power of 2
+ if (Pred == ICmpInst::ICMP_ULT && C2->isPowerOf2() && (C == -(*C2)))
+ return new ICmpInst(ICmpInst::ICMP_NE, Builder.CreateAnd(X, C),
+ ConstantInt::get(Ty, C * 2));
+
// X+C >u C2 -> (X & ~C2) != C
// iff C & C2 == 0
// C2+1 is a power of 2
diff --git a/llvm/test/Transforms/InstCombine/icmp-add.ll b/llvm/test/Transforms/InstCombine/icmp-add.ll
index 84bd3c3d79020..f5e8a58580ce8 100644
--- a/llvm/test/Transforms/InstCombine/icmp-add.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-add.ll
@@ -3025,8 +3025,8 @@ define i1 @icmp_addnuw_nonzero_fail_multiuse(i32 %x, i32 %y) {
define i1 @ult_add_C2_pow2_C_neg(i8 %x) {
; CHECK-LABEL: @ult_add_C2_pow2_C_neg(
-; CHECK-NEXT: [[I:%.*]] = add i8 [[X:%.*]], 32
-; CHECK-NEXT: [[C:%.*]] = icmp ult i8 [[I]], -32
+; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X:%.*]], -32
+; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[TMP1]], -64
; CHECK-NEXT: ret i1 [[C]]
;
%i = add i8 %x, 32
@@ -3036,8 +3036,8 @@ define i1 @ult_add_C2_pow2_C_neg(i8 %x) {
define i1 @ult_add_nsw_C2_pow2_C_neg(i8 %x) {
; CHECK-LABEL: @ult_add_nsw_C2_pow2_C_neg(
-; CHECK-NEXT: [[I:%.*]] = add nsw i8 [[X:%.*]], 32
-; CHECK-NEXT: [[C:%.*]] = icmp ult i8 [[I]], -32
+; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X:%.*]], -32
+; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[TMP1]], -64
; CHECK-NEXT: ret i1 [[C]]
;
%i = add nsw i8 %x, 32
@@ -3068,8 +3068,8 @@ define i1 @ult_add_C2_neg_C_pow2(i8 %x) {
define <2 x i1> @ult_add_C2_pow2_C_neg_vec(<2 x i8> %x) {
; CHECK-LABEL: @ult_add_C2_pow2_C_neg_vec(
-; CHECK-NEXT: [[I:%.*]] = add <2 x i8> [[X:%.*]], <i8 32, i8 32>
-; CHECK-NEXT: [[C:%.*]] = icmp ult <2 x i8> [[I]], <i8 -32, i8 -32>
+; CHECK-NEXT: [[TMP1:%.*]] = and <2 x i8> [[X:%.*]], <i8 -32, i8 -32>
+; CHECK-NEXT: [[C:%.*]] = icmp ne <2 x i8> [[TMP1]], <i8 -64, i8 -64>
; CHECK-NEXT: ret <2 x i1> [[C]]
;
%i = add <2 x i8> %x, <i8 32, i8 32>
>From 797932a46f3d7aaacdb647a5d50959b419f88567 Mon Sep 17 00:00:00 2001
From: Antonio Frighetto <me at antoniofrighetto.com>
Date: Sun, 16 Jun 2024 10:55:35 +0200
Subject: [PATCH 3/3] !fixup style, add multiuse
---
.../Transforms/InstCombine/InstCombineCompares.cpp | 2 +-
llvm/test/Transforms/InstCombine/icmp-add.ll | 13 +++++++++++++
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 51dd3384c1fb5..522c31f9e3e71 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3133,7 +3133,7 @@ Instruction *InstCombinerImpl::foldICmpAddConstant(ICmpInst &Cmp,
// X+C2 <u C -> (X & C) == 2C
// iff C == -(C2)
// C2 is a power of 2
- if (Pred == ICmpInst::ICMP_ULT && C2->isPowerOf2() && (C == -(*C2)))
+ if (Pred == ICmpInst::ICMP_ULT && C2->isPowerOf2() && C == -*C2)
return new ICmpInst(ICmpInst::ICMP_NE, Builder.CreateAnd(X, C),
ConstantInt::get(Ty, C * 2));
diff --git a/llvm/test/Transforms/InstCombine/icmp-add.ll b/llvm/test/Transforms/InstCombine/icmp-add.ll
index f5e8a58580ce8..baa6f3d51a40e 100644
--- a/llvm/test/Transforms/InstCombine/icmp-add.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-add.ll
@@ -3077,6 +3077,19 @@ define <2 x i1> @ult_add_C2_pow2_C_neg_vec(<2 x i8> %x) {
ret <2 x i1> %c
}
+define i1 @ult_add_C2_pow2_C_neg_multiuse(i8 %x) {
+; CHECK-LABEL: @ult_add_C2_pow2_C_neg_multiuse(
+; CHECK-NEXT: [[I:%.*]] = add i8 [[X:%.*]], 32
+; CHECK-NEXT: [[C:%.*]] = icmp ult i8 [[I]], -32
+; CHECK-NEXT: call void @use(i8 [[I]])
+; CHECK-NEXT: ret i1 [[C]]
+;
+ %i = add i8 %x, 32
+ %c = icmp ult i8 %i, -32
+ call void @use(i8 %i)
+ ret i1 %c
+}
+
define i1 @uge_add_C2_pow2_C_neg(i8 %x) {
; CHECK-LABEL: @uge_add_C2_pow2_C_neg(
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X:%.*]], -32
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