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[InstCombine] fold udiv with sext bool divisor

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Note: I didn't add a hasOneUse() check because the existing,
related fold doesn't have that check. I suspect that the
improved analysis and codegen make these some of the rare
canonicalization cases where we allow an increase in
instructions.

llvm-svn: 335597
This commit is contained in:
Sanjay Patel 2018-06-26 12:41:15 +00:00
parent 0c43fe0de7
commit 70547e8323
2 changed files with 11 additions and 5 deletions
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8
lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
View File

@ -954,9 +954,15 @@ Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
// Op0 / C where C is large (negative) --> zext (Op0 >= C)
// TODO: Could use isKnownNegative() to handle non-constant values.
Type *Ty = I.getType();
if (match(Op1, m_Negative())) {
Value *Cmp = Builder.CreateICmpUGE(Op0, Op1);
return CastInst::CreateZExtOrBitCast(Cmp, I.getType());
return CastInst::CreateZExtOrBitCast(Cmp, Ty);
}
// Op0 / (sext i1 X) --> zext (Op0 == -1) (if X is 0, the div is undefined)
if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) {
Value *Cmp = Builder.CreateICmpEQ(Op0, ConstantInt::getAllOnesValue(Ty));
return CastInst::CreateZExtOrBitCast(Cmp, Ty);
}
if (Instruction *NarrowDiv = narrowUDivURem(I, Builder))

8
test/Transforms/InstCombine/div.ll
View File

@ -98,8 +98,8 @@ define <2 x i64> @udiv_by_minus1_vec(<2 x i64> %x) {
define i32 @udiv_by_sext_all_ones(i1 %x, i32 %y) {
; CHECK-LABEL: @udiv_by_sext_all_ones(
; CHECK-NEXT: [[SEXT:%.*]] = sext i1 [[X:%.*]] to i32
; CHECK-NEXT: [[DIV:%.*]] = udiv i32 [[Y:%.*]], [[SEXT]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp eq i32 [[Y:%.*]], -1
; CHECK-NEXT: [[DIV:%.*]] = zext i1 [[TMP1]] to i32
; CHECK-NEXT: ret i32 [[DIV]]
;
%sext = sext i1 %x to i32
@ -109,8 +109,8 @@ define i32 @udiv_by_sext_all_ones(i1 %x, i32 %y) {
define <2 x i32> @udiv_by_sext_all_ones_vec(<2 x i1> %x, <2 x i32> %y) {
; CHECK-LABEL: @udiv_by_sext_all_ones_vec(
; CHECK-NEXT: [[SEXT:%.*]] = sext <2 x i1> [[X:%.*]] to <2 x i32>
; CHECK-NEXT: [[DIV:%.*]] = udiv <2 x i32> [[Y:%.*]], [[SEXT]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp eq <2 x i32> [[Y:%.*]], <i32 -1, i32 -1>
; CHECK-NEXT: [[DIV:%.*]] = zext <2 x i1> [[TMP1]] to <2 x i32>
; CHECK-NEXT: ret <2 x i32> [[DIV]]
;
%sext = sext <2 x i1> %x to <2 x i32>