[llvm] [InstCombine] Simplifiy `sdiv -X, X` into `X == INT_MIN ? 1 : -1` (PR #71768)
via llvm-commits
llvm-commits at lists.llvm.org
Wed Nov 15 06:04:48 PST 2023
https://github.com/Z572 updated https://github.com/llvm/llvm-project/pull/71768
>From 203b618103005ba126dd7c382a93daafab663382 Mon Sep 17 00:00:00 2001
From: Zheng Junjie <zhengjunjie at iscas.ac.cn>
Date: Wed, 8 Nov 2023 11:25:15 +0800
Subject: [PATCH 1/4] [InstCombine] Simplifiy sdiv -X, X into X == INT_MIN ? 1
: -1
---
.../InstCombine/InstCombineMulDivRem.cpp | 7 +++
llvm/test/Transforms/InstCombine/div.ll | 55 +++++++++++++++++++
2 files changed, 62 insertions(+)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index db0804380855e3a..d6fac88a39d01be 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -1544,6 +1544,13 @@ Instruction *InstCombinerImpl::visitSDiv(BinaryOperator &I) {
}
}
+ // -X / X --> X == INT_MIN ? 1 : -1
+ if (isKnownNegation(Op0, Op1)) {
+ APInt MinVal = APInt::getSignedMinValue(Ty->getScalarSizeInBits());
+ Value *Cond = Builder.CreateICmpEQ(Op0, ConstantInt::get(Ty, MinVal));
+ return SelectInst::Create(Cond, ConstantInt::get(Ty, 1),
+ ConstantInt::getAllOnesValue(Ty));
+ }
return nullptr;
}
diff --git a/llvm/test/Transforms/InstCombine/div.ll b/llvm/test/Transforms/InstCombine/div.ll
index 1f0081befb07dba..69c02bcebeada77 100644
--- a/llvm/test/Transforms/InstCombine/div.ll
+++ b/llvm/test/Transforms/InstCombine/div.ll
@@ -1432,6 +1432,61 @@ define <2 x i8> @sdiv_sdiv_mul_nsw(<2 x i8> %x, <2 x i8> %y, <2 x i8> %z) {
ret <2 x i8> %r
}
+define i32 @sdiv_sub1(i32 %arg) {
+; CHECK-LABEL: @sdiv_sub1(
+; CHECK-NEXT: [[TMP1:%.*]] = icmp eq i32 [[ARG:%.*]], -2147483648
+; CHECK-NEXT: [[DIV:%.*]] = select i1 [[TMP1]], i32 1, i32 -1
+; CHECK-NEXT: ret i32 [[DIV]]
+;
+ %neg = sub i32 0, %arg
+ %div = sdiv i32 %neg, %arg
+ ret i32 %div
+}
+
+define i32 @sdiv_sub2(i32 %arg) {
+; CHECK-LABEL: @sdiv_sub2(
+; CHECK-NEXT: [[TMP1:%.*]] = icmp eq i32 [[ARG:%.*]], -2147483648
+; CHECK-NEXT: [[DIV:%.*]] = select i1 [[TMP1]], i32 1, i32 -1
+; CHECK-NEXT: ret i32 [[DIV]]
+;
+ %neg = sub i32 0, %arg
+ %div = sdiv i32 %arg, %neg
+ ret i32 %div
+}
+
+define i32 @sdiv_mul_sub(i32 %x, i32 %y) {
+; CHECK-LABEL: @sdiv_mul_sub(
+; CHECK-NEXT: [[M:%.*]] = mul i32 [[Y:%.*]], [[X:%.*]]
+; CHECK-NEXT: [[TMP1:%.*]] = icmp eq i32 [[M]], -2147483648
+; CHECK-NEXT: [[R:%.*]] = select i1 [[TMP1]], i32 1, i32 -1
+; CHECK-NEXT: ret i32 [[R]]
+;
+ %m = mul i32 %y, %x
+ %d = sub i32 0, %m
+ %r = sdiv i32 %d, %m
+ ret i32 %r
+}
+
+define i32 @sdiv_mul_sub_nsw(i32 %x, i32 %y) {
+; CHECK-LABEL: @sdiv_mul_sub_nsw(
+; CHECK-NEXT: ret i32 -1
+;
+ %m = mul i32 %y, %x
+ %n = sub nsw i32 0, %m
+ %d = sdiv i32 %m, %n
+ ret i32 %d
+}
+
+define i32 @sdiv_mul_nsw_sub_nsw(i32 %x, i32 %y) {
+; CHECK-LABEL: @sdiv_mul_nsw_sub_nsw(
+; CHECK-NEXT: ret i32 -1
+;
+ %m = mul nsw i32 %y, %x
+ %n = sub nsw i32 0, %m
+ %d = sdiv i32 %m, %n
+ ret i32 %d
+}
+
; exact propagates
define i8 @sdiv_sdiv_mul_nsw_exact_exact(i8 %x, i8 %y, i8 %z) {
>From 71b823960e2a932063d00dff5cf72a66f8c46cc2 Mon Sep 17 00:00:00 2001
From: Zheng Junjie <zhengjunjie at iscas.ac.cn>
Date: Wed, 15 Nov 2023 19:55:06 +0800
Subject: [PATCH 2/4] fixup! [InstCombine] Simplifiy sdiv -X, X into X ==
INT_MIN ? 1 : -1
---
llvm/test/Transforms/InstCombine/div.ll | 26 +++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/llvm/test/Transforms/InstCombine/div.ll b/llvm/test/Transforms/InstCombine/div.ll
index 69c02bcebeada77..d183e1860a0bbf1 100644
--- a/llvm/test/Transforms/InstCombine/div.ll
+++ b/llvm/test/Transforms/InstCombine/div.ll
@@ -1454,6 +1454,32 @@ define i32 @sdiv_sub2(i32 %arg) {
ret i32 %div
}
+define i32 @sub_sdiv_sub(i32 %arg) {
+; CHECK-LABEL: @sub_sdiv_sub(
+; CHECK-NEXT: [[TMP1:%.*]] = icmp eq i32 [[ARG:%.*]], -2147483648
+; CHECK-NEXT: [[DIV:%.*]] = select i1 [[TMP1]], i32 1, i32 -1
+; CHECK-NEXT: [[SUB:%.*]] = add i32 [[DIV]], [[ARG]]
+; CHECK-NEXT: ret i32 [[SUB]]
+;
+ %neg = sub i32 0, %arg
+ %div = sdiv i32 %arg, %neg
+ %sub = sub i32 %div, %neg
+ ret i32 %sub
+}
+
+define i32 @sdiv_sub_sub(i32 %x ,i32 %y) {
+; CHECK-LABEL: @sdiv_sub_sub(
+; CHECK-NEXT: [[S:%.*]] = sub i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: [[TMP1:%.*]] = icmp eq i32 [[S]], -2147483648
+; CHECK-NEXT: [[D:%.*]] = select i1 [[TMP1]], i32 1, i32 -1
+; CHECK-NEXT: ret i32 [[D]]
+;
+ %s = sub i32 %x, %y
+ %u = sub i32 %y, %x
+ %d = sdiv i32 %s, %u
+ ret i32 %d
+}
+
define i32 @sdiv_mul_sub(i32 %x, i32 %y) {
; CHECK-LABEL: @sdiv_mul_sub(
; CHECK-NEXT: [[M:%.*]] = mul i32 [[Y:%.*]], [[X:%.*]]
>From 62855d15eac01044c821c41ed0fc41463ce8c809 Mon Sep 17 00:00:00 2001
From: Zheng Junjie <zhengjunjie at iscas.ac.cn>
Date: Wed, 15 Nov 2023 20:31:14 +0800
Subject: [PATCH 3/4] fixup! fixup! [InstCombine] Simplifiy sdiv -X, X into X
== INT_MIN ? 1 : -1
---
llvm/test/Transforms/InstCombine/div.ll | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/llvm/test/Transforms/InstCombine/div.ll b/llvm/test/Transforms/InstCombine/div.ll
index d183e1860a0bbf1..dd61a5bd1ac3b8f 100644
--- a/llvm/test/Transforms/InstCombine/div.ll
+++ b/llvm/test/Transforms/InstCombine/div.ll
@@ -1456,13 +1456,16 @@ define i32 @sdiv_sub2(i32 %arg) {
define i32 @sub_sdiv_sub(i32 %arg) {
; CHECK-LABEL: @sub_sdiv_sub(
-; CHECK-NEXT: [[TMP1:%.*]] = icmp eq i32 [[ARG:%.*]], -2147483648
+; CHECK-NEXT: [[NEG:%.*]] = sub i32 0, [[ARG:%.*]]
+; CHECK-NEXT: [[TMP1:%.*]] = icmp eq i32 [[ARG]], -2147483648
; CHECK-NEXT: [[DIV:%.*]] = select i1 [[TMP1]], i32 1, i32 -1
+; CHECK-NEXT: call void @use(i32 [[NEG]])
; CHECK-NEXT: [[SUB:%.*]] = add i32 [[DIV]], [[ARG]]
; CHECK-NEXT: ret i32 [[SUB]]
;
%neg = sub i32 0, %arg
%div = sdiv i32 %arg, %neg
+ call void @use(i32 %neg)
%sub = sub i32 %div, %neg
ret i32 %sub
}
>From 03c0c9c55dfb7d1f27c2528fd3c7bba602614b67 Mon Sep 17 00:00:00 2001
From: Zheng Junjie <zhengjunjie at iscas.ac.cn>
Date: Wed, 15 Nov 2023 22:03:56 +0800
Subject: [PATCH 4/4] fixup! fixup! fixup! [InstCombine] Simplifiy sdiv -X, X
into X == INT_MIN ? 1 : -1
---
llvm/test/Transforms/InstCombine/div.ll | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/llvm/test/Transforms/InstCombine/div.ll b/llvm/test/Transforms/InstCombine/div.ll
index dd61a5bd1ac3b8f..844b35723b135c9 100644
--- a/llvm/test/Transforms/InstCombine/div.ll
+++ b/llvm/test/Transforms/InstCombine/div.ll
@@ -1454,20 +1454,18 @@ define i32 @sdiv_sub2(i32 %arg) {
ret i32 %div
}
-define i32 @sub_sdiv_sub(i32 %arg) {
-; CHECK-LABEL: @sub_sdiv_sub(
+define i32 @sub_sdiv_multiuse(i32 %arg) {
+; CHECK-LABEL: @sub_sdiv_multiuse(
; CHECK-NEXT: [[NEG:%.*]] = sub i32 0, [[ARG:%.*]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp eq i32 [[ARG]], -2147483648
; CHECK-NEXT: [[DIV:%.*]] = select i1 [[TMP1]], i32 1, i32 -1
; CHECK-NEXT: call void @use(i32 [[NEG]])
-; CHECK-NEXT: [[SUB:%.*]] = add i32 [[DIV]], [[ARG]]
-; CHECK-NEXT: ret i32 [[SUB]]
+; CHECK-NEXT: ret i32 [[DIV]]
;
%neg = sub i32 0, %arg
%div = sdiv i32 %arg, %neg
call void @use(i32 %neg)
- %sub = sub i32 %div, %neg
- ret i32 %sub
+ ret i32 %div
}
define i32 @sdiv_sub_sub(i32 %x ,i32 %y) {
More information about the llvm-commits
mailing list