maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

Revert "[InstCombine] generalize subtract with 'not' operands" 

This reverts commit 3aa009cc87.

The reverted commit causes an infinite loop in instcombine. See PR51584.
This commit is contained in:
Florian Hahn 2021-08-23 15:31:48 +01:00
parent 628eaa4cf7
commit 9577fac0fd
No known key found for this signature in database
GPG Key ID: 61D7554B5CECDC0D
4 changed files with 15 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
View File

@ -1829,15 +1829,11 @@ Instruction *InstCombinerImpl::visitSub(BinaryOperator &I) {
return BinaryOperator::CreateNot(Op1);
// (~X) - (~Y) --> Y - X
if (isFreeToInvert(Op0, Op0->hasOneUse()) &&
isFreeToInvert(Op1, Op1->hasOneUse())) {
Value *NotOp0 = Builder.CreateNot(Op0);
Value *NotOp1 = Builder.CreateNot(Op1);
return BinaryOperator::CreateSub(NotOp1, NotOp0);
}
Value *X, *Y;
if (match(Op0, m_Not(m_Value(X))) && match(Op1, m_Not(m_Value(Y))))
return BinaryOperator::CreateSub(Y, X);
// (X + -1) - Y --> ~Y + X
Value *X, *Y;
if (match(Op0, m_OneUse(m_Add(m_Value(X), m_AllOnes()))))
return BinaryOperator::CreateAdd(Builder.CreateNot(Op1), X);

4
llvm/test/Transforms/InstCombine/minmax-intrinsics.ll
View File

@ -1157,8 +1157,8 @@ define i8 @freeToInvertSub(i8 %x, i8 %y, i8 %z) {
; CHECK-NEXT: call void @use(i8 [[NX]])
; CHECK-NEXT: call void @use(i8 [[NY]])
; CHECK-NEXT: call void @use(i8 [[NZ]])
; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.umin.i8(i8 [[X]], i8 [[Y]])
; CHECK-NEXT: [[SUB:%.*]] = sub i8 [[TMP1]], [[Z]]
; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.umax.i8(i8 [[NX]], i8 [[NY]])
; CHECK-NEXT: [[SUB:%.*]] = sub i8 [[NZ]], [[M]]
; CHECK-NEXT: ret i8 [[SUB]]
;
%nx = xor i8 %x, -1

5
llvm/test/Transforms/InstCombine/reassociate-nuw.ll
View File

@ -79,8 +79,9 @@ define i32 @reassoc_x2_mul_nuw(i32 %x, i32 %y) {
define i32 @reassoc_x2_sub_nuw(i32 %x, i32 %y) {
; CHECK-LABEL: @reassoc_x2_sub_nuw(
; CHECK-NEXT: [[TMP1:%.*]] = sub i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[SUB2:%.*]] = add i32 [[TMP1]], 4
; CHECK-NEXT: [[SUB0:%.*]] = add i32 [[X:%.*]], -4
; CHECK-NEXT: [[SUB1:%.*]] = add i32 [[Y:%.*]], -8
; CHECK-NEXT: [[SUB2:%.*]] = sub nuw i32 [[SUB0]], [[SUB1]]
; CHECK-NEXT: ret i32 [[SUB2]]
;
%sub0 = sub nuw i32 %x, 4

9
llvm/test/Transforms/InstCombine/sub.ll
View File

@ -1109,9 +1109,14 @@ define i32 @test57(i32 %A, i32 %B) {
@dummy_global2 = external global i8*
define i64 @test58([100 x [100 x i8]]* %foo, i64 %i, i64 %j) {
; Note the reassociate pass and another instcombine pass will further optimize this to
; "%sub = i64 %i, %j, ret i64 %sub"
; gep1 and gep2 have only one use
; CHECK-LABEL: @test58(
; CHECK-NEXT: [[TMP1:%.*]] = sub i64 [[I:%.*]], [[J:%.*]]
; CHECK-NEXT: ret i64 [[TMP1]]
; CHECK-NEXT: [[GEP1_OFFS:%.*]] = add nsw i64 [[I:%.*]], 4200
; CHECK-NEXT: [[GEP2_OFFS:%.*]] = add nsw i64 [[J:%.*]], 4200
; CHECK-NEXT: [[GEPDIFF:%.*]] = sub nsw i64 [[GEP1_OFFS]], [[GEP2_OFFS]]
; CHECK-NEXT: ret i64 [[GEPDIFF]]
;
%gep1 = getelementptr inbounds [100 x [100 x i8]], [100 x [100 x i8]]* %foo, i64 0, i64 42, i64 %i
%gep2 = getelementptr inbounds [100 x [100 x i8]], [100 x [100 x i8]]* %foo, i64 0, i64 42, i64 %j