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[InstCombine] Canonicalize (-X s/ Y) to -(X s/ Y).

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Differential Revision: https://reviews.llvm.org/D60395

llvm-svn: 358050
This commit is contained in:
Chen Zheng 2019-04-10 06:52:09 +00:00
parent 0c01607bbf
commit 5e13ff1da2
3 changed files with 21 additions and 15 deletions
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6
llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
View File

@ -1056,6 +1056,12 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
}
}
// -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()));

12
llvm/test/Transforms/InstCombine/div.ll
View File

@ -522,8 +522,8 @@ define <2 x i8> @sdiv_negated_dividend_constant_divisor_vec_undef(<2 x i8> %x) {
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_constant_divisor_vec(<2 x i64> %x) {
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_dividend_constant_divisor_vec(<2 x i64> %x)
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

18
llvm/test/Transforms/InstCombine/sdiv-canonicalize.ll
View File

@ -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(i32 %x, i32 %y) {
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_exact(i32 %x, i32 %y) {
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(i32 %x, i32 %y) {
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_multiple_uses(i32 %x, i32 %y) {
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