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[InstSimplify] Fix addo/subo undef folds (PR42209)

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Fix folds of addo and subo with an undef operand to be:

`@llvm.{u,s}{add,sub}.with.overflow` all fold to `{ undef, false }`,
 as per LLVM undef rules.
Same for commuted variants.

Based on the original version of the patch by @nikic.

Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=42209 | PR42209 ]]

Differential Revision: https://reviews.llvm.org/D63065

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363522 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Roman Lebedev
2019-06-16 20:39:45 +00:00
parent e51018c229
commit d09f140cd1
3 changed files with 20 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/Analysis/InstructionSimplify.cpp
+11 -8
View File
@@ -4843,16 +4843,19 @@ static Value *simplifyBinaryIntrinsic(Function *F, Value *Op0, Value *Op1,
// X - X -> { 0, false }
if (Op0 == Op1)
return Constant::getNullValue(ReturnType);
// X - undef -> undef
// undef - X -> undef
if (isa<UndefValue>(Op0) || isa<UndefValue>(Op1))
return UndefValue::get(ReturnType);
break;
LLVM_FALLTHROUGH;
case Intrinsic::uadd_with_overflow:
case Intrinsic::sadd_with_overflow:
// X + undef -> undef
if (isa<UndefValue>(Op0) || isa<UndefValue>(Op1))
return UndefValue::get(ReturnType);
// X - undef -> { undef, false }
// undef - X -> { undef, false }
// X + undef -> { undef, false }
// undef + x -> { undef, false }
if (isa<UndefValue>(Op0) || isa<UndefValue>(Op1)) {
return ConstantStruct::get(
cast<StructType>(ReturnType),
{UndefValue::get(ReturnType->getStructElementType(0)),
Constant::getNullValue(ReturnType->getStructElementType(1))});
}
break;
case Intrinsic::umul_with_overflow:
case Intrinsic::smul_with_overflow:
test/Transforms/InstCombine/with_overflow.ll
+1
View File
@@ -60,6 +60,7 @@ define i8 @uaddtest3(i8 %A, i8 %B, i1* %overflowPtr) {
define i8 @uaddtest4(i8 %A, i1* %overflowPtr) {
; CHECK-LABEL: @uaddtest4(
; CHECK-NEXT: store i1 false, i1* [[OVERFLOWPTR:%.*]], align 1
; CHECK-NEXT: ret i8 undef
;
%x = call { i8, i1 } @llvm.uadd.with.overflow.i8(i8 undef, i8 %A)
test/Transforms/InstSimplify/call.ll
+8 -8
View File
@@ -29,7 +29,7 @@ define i8 @test_uadd2() {
define {i8, i1} @test_uadd3(i8 %v) {
; CHECK-LABEL: @test_uadd3(
; CHECK-NEXT: ret { i8, i1 } undef
; CHECK-NEXT: ret { i8, i1 } { i8 undef, i1 false }
;
%result = call {i8, i1} @llvm.uadd.with.overflow.i8(i8 %v, i8 undef)
ret {i8, i1} %result
@@ -37,7 +37,7 @@ define {i8, i1} @test_uadd3(i8 %v) {
define {i8, i1} @test_uadd4(i8 %v) {
; CHECK-LABEL: @test_uadd4(
; CHECK-NEXT: ret { i8, i1 } undef
; CHECK-NEXT: ret { i8, i1 } { i8 undef, i1 false }
;
%result = call {i8, i1} @llvm.uadd.with.overflow.i8(i8 undef, i8 %v)
ret {i8, i1} %result
@@ -63,7 +63,7 @@ define i8 @test_sadd2() {
define {i8, i1} @test_sadd3(i8 %v) {
; CHECK-LABEL: @test_sadd3(
; CHECK-NEXT: ret { i8, i1 } undef
; CHECK-NEXT: ret { i8, i1 } { i8 undef, i1 false }
;
%result = call {i8, i1} @llvm.sadd.with.overflow.i8(i8 %v, i8 undef)
ret {i8, i1} %result
@@ -71,7 +71,7 @@ define {i8, i1} @test_sadd3(i8 %v) {
define {i8, i1} @test_sadd4(i8 %v) {
; CHECK-LABEL: @test_sadd4(
; CHECK-NEXT: ret { i8, i1 } undef
; CHECK-NEXT: ret { i8, i1 } { i8 undef, i1 false }
;
%result = call {i8, i1} @llvm.sadd.with.overflow.i8(i8 undef, i8 %v)
ret {i8, i1} %result
@@ -87,7 +87,7 @@ define {i8, i1} @test_usub1(i8 %V) {
define {i8, i1} @test_usub2(i8 %V) {
; CHECK-LABEL: @test_usub2(
; CHECK-NEXT: ret { i8, i1 } undef
; CHECK-NEXT: ret { i8, i1 } { i8 undef, i1 false }
;
%x = call {i8, i1} @llvm.usub.with.overflow.i8(i8 %V, i8 undef)
ret {i8, i1} %x
@@ -95,7 +95,7 @@ define {i8, i1} @test_usub2(i8 %V) {
define {i8, i1} @test_usub3(i8 %V) {
; CHECK-LABEL: @test_usub3(
; CHECK-NEXT: ret { i8, i1 } undef
; CHECK-NEXT: ret { i8, i1 } { i8 undef, i1 false }
;
%x = call {i8, i1} @llvm.usub.with.overflow.i8(i8 undef, i8 %V)
ret {i8, i1} %x
@@ -111,7 +111,7 @@ define {i8, i1} @test_ssub1(i8 %V) {
define {i8, i1} @test_ssub2(i8 %V) {
; CHECK-LABEL: @test_ssub2(
; CHECK-NEXT: ret { i8, i1 } undef
; CHECK-NEXT: ret { i8, i1 } { i8 undef, i1 false }
;
%x = call {i8, i1} @llvm.ssub.with.overflow.i8(i8 %V, i8 undef)
ret {i8, i1} %x
@@ -119,7 +119,7 @@ define {i8, i1} @test_ssub2(i8 %V) {
define {i8, i1} @test_ssub3(i8 %V) {
; CHECK-LABEL: @test_ssub3(
; CHECK-NEXT: ret { i8, i1 } undef
; CHECK-NEXT: ret { i8, i1 } { i8 undef, i1 false }
;
%x = call {i8, i1} @llvm.ssub.with.overflow.i8(i8 undef, i8 %V)
ret {i8, i1} %x