[llvm] r358050 - [InstCombine] Canonicalize (-X s/ Y) to -(X s/ Y).
Chen Zheng via llvm-commits
llvm-commits at lists.llvm.org
Tue Apr 9 23:52:09 PDT 2019
Author: shchenz
Date: Tue Apr 9 23:52:09 2019
New Revision: 358050
URL: http://llvm.org/viewvc/llvm-project?rev=358050&view=rev
Log:
[InstCombine] Canonicalize (-X s/ Y) to -(X s/ Y).
Differential Revision: https://reviews.llvm.org/D60395
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
llvm/trunk/test/Transforms/InstCombine/div.ll
llvm/trunk/test/Transforms/InstCombine/sdiv-canonicalize.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp?rev=358050&r1=358049&r2=358050&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp Tue Apr 9 23:52:09 2019
@@ -1056,6 +1056,12 @@ Instruction *InstCombiner::visitSDiv(Bin
}
}
+ // -X / Y --> -(X / Y)
+ Value *Y;
+ if (match(&I, m_SDiv(m_OneUse(m_NSWSub(m_Zero(), m_Value(X))), m_Value(Y))))
+ return BinaryOperator::CreateNSWNeg(
+ Builder.CreateSDiv(X, Y, I.getName(), I.isExact()));
+
// If the sign bits of both operands are zero (i.e. we can prove they are
// unsigned inputs), turn this into a udiv.
APInt Mask(APInt::getSignMask(I.getType()->getScalarSizeInBits()));
Modified: llvm/trunk/test/Transforms/InstCombine/div.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/div.ll?rev=358050&r1=358049&r2=358050&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/div.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/div.ll Tue Apr 9 23:52:09 2019
@@ -522,8 +522,8 @@ define <2 x i8> @sdiv_negated_dividend_c
define <2 x i64> @sdiv_negated_dividend_constant_divisor_vec(<2 x i64> %x) {
; CHECK-LABEL: @sdiv_negated_dividend_constant_divisor_vec(
-; CHECK-NEXT: [[NEG:%.*]] = sub nsw <2 x i64> zeroinitializer, [[X:%.*]]
-; CHECK-NEXT: [[DIV:%.*]] = sdiv <2 x i64> [[NEG]], <i64 3, i64 4>
+; CHECK-NEXT: [[DIV1:%.*]] = sdiv <2 x i64> [[X:%.*]], <i64 3, i64 4>
+; CHECK-NEXT: [[DIV:%.*]] = sub nsw <2 x i64> zeroinitializer, [[DIV1]]
; CHECK-NEXT: ret <2 x i64> [[DIV]]
;
%neg = sub nsw <2 x i64> zeroinitializer, %x
@@ -533,8 +533,8 @@ define <2 x i64> @sdiv_negated_dividend_
define <2 x i64> @sdiv_exact_negated_dividend_constant_divisor_vec(<2 x i64> %x) {
; CHECK-LABEL: @sdiv_exact_negated_dividend_constant_divisor_vec(
-; CHECK-NEXT: [[NEG:%.*]] = sub nsw <2 x i64> zeroinitializer, [[X:%.*]]
-; CHECK-NEXT: [[DIV:%.*]] = sdiv exact <2 x i64> [[NEG]], <i64 3, i64 4>
+; CHECK-NEXT: [[DIV1:%.*]] = sdiv exact <2 x i64> [[X:%.*]], <i64 3, i64 4>
+; CHECK-NEXT: [[DIV:%.*]] = sub nsw <2 x i64> zeroinitializer, [[DIV1]]
; CHECK-NEXT: ret <2 x i64> [[DIV]]
;
%neg = sub nsw <2 x i64> zeroinitializer, %x
@@ -546,8 +546,8 @@ define <2 x i64> @sdiv_exact_negated_div
define <2 x i8> @sdiv_exact_negated_dividend_constant_divisor_vec_overflow(<2 x i8> %x) {
; CHECK-LABEL: @sdiv_exact_negated_dividend_constant_divisor_vec_overflow(
-; CHECK-NEXT: [[NEG:%.*]] = sub nsw <2 x i8> zeroinitializer, [[X:%.*]]
-; CHECK-NEXT: [[DIV:%.*]] = sdiv exact <2 x i8> [[NEG]], <i8 -128, i8 42>
+; CHECK-NEXT: [[DIV1:%.*]] = sdiv exact <2 x i8> [[X:%.*]], <i8 -128, i8 42>
+; CHECK-NEXT: [[DIV:%.*]] = sub nsw <2 x i8> zeroinitializer, [[DIV1]]
; CHECK-NEXT: ret <2 x i8> [[DIV]]
;
%neg = sub nsw <2 x i8> zeroinitializer, %x
Modified: llvm/trunk/test/Transforms/InstCombine/sdiv-canonicalize.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/sdiv-canonicalize.ll?rev=358050&r1=358049&r2=358050&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/sdiv-canonicalize.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/sdiv-canonicalize.ll Tue Apr 9 23:52:09 2019
@@ -3,8 +3,8 @@
define i32 @test_sdiv_canonicalize_op0(i32 %x, i32 %y) {
; CHECK-LABEL: @test_sdiv_canonicalize_op0(
-; CHECK-NEXT: [[NEG:%.*]] = sub nsw i32 0, [[X:%.*]]
-; CHECK-NEXT: [[SDIV:%.*]] = sdiv i32 [[NEG]], [[Y:%.*]]
+; CHECK-NEXT: [[SDIV1:%.*]] = sdiv i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: [[SDIV:%.*]] = sub nsw i32 0, [[SDIV1]]
; CHECK-NEXT: ret i32 [[SDIV]]
;
%neg = sub nsw i32 0, %x
@@ -14,8 +14,8 @@ define i32 @test_sdiv_canonicalize_op0(i
define i32 @test_sdiv_canonicalize_op0_exact(i32 %x, i32 %y) {
; CHECK-LABEL: @test_sdiv_canonicalize_op0_exact(
-; CHECK-NEXT: [[NEG:%.*]] = sub nsw i32 0, [[X:%.*]]
-; CHECK-NEXT: [[SDIV:%.*]] = sdiv exact i32 [[NEG]], [[Y:%.*]]
+; CHECK-NEXT: [[SDIV1:%.*]] = sdiv exact i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: [[SDIV:%.*]] = sub nsw i32 0, [[SDIV1]]
; CHECK-NEXT: ret i32 [[SDIV]]
;
%neg = sub nsw i32 0, %x
@@ -23,6 +23,7 @@ define i32 @test_sdiv_canonicalize_op0_e
ret i32 %sdiv
}
+; (X/-Y) is not equal to -(X/Y), don't canonicalize.
define i32 @test_sdiv_canonicalize_op1(i32 %x, i32 %z) {
; CHECK-LABEL: @test_sdiv_canonicalize_op1(
; CHECK-NEXT: [[Y:%.*]] = mul i32 [[Z:%.*]], 3
@@ -49,8 +50,8 @@ define i32 @test_sdiv_canonicalize_nonsw
define <2 x i32> @test_sdiv_canonicalize_vec(<2 x i32> %x, <2 x i32> %y) {
; CHECK-LABEL: @test_sdiv_canonicalize_vec(
-; CHECK-NEXT: [[NEG:%.*]] = sub nsw <2 x i32> zeroinitializer, [[X:%.*]]
-; CHECK-NEXT: [[SDIV:%.*]] = sdiv <2 x i32> [[NEG]], [[Y:%.*]]
+; CHECK-NEXT: [[SDIV1:%.*]] = sdiv <2 x i32> [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: [[SDIV:%.*]] = sub nsw <2 x i32> zeroinitializer, [[SDIV1]]
; CHECK-NEXT: ret <2 x i32> [[SDIV]]
;
%neg = sub nsw <2 x i32> <i32 0, i32 0>, %x
@@ -71,9 +72,8 @@ define i32 @test_sdiv_canonicalize_multi
ret i32 %sdiv2
}
-; There is combination: (X/-CE) -> -(X/CE)
-; There is another combination: -(X/CE) -> (X/-CE)
-; Make sure don't combine them endless.
+; There is combination: -(X/CE) -> (X/-CE).
+; If combines (X/-CE) to -(X/CE), make sure don't combine them endless.
@X = global i32 5
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