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[InstCombine] support fold select(X|Y,X|Y,X) to X|Y
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Fixed: #62113
Add addtional check in `visitSelectInst` to:
1. match `select(X|Y==0, X, X|Y)` and replaced with `X|Y`
2. match `select(X&Y==-1, X, X&Y)` and replaced with `X&Y`

alive proof:
https://alive2.llvm.org/ce/z/4qHmv-
https://alive2.llvm.org/ce/z/c2MBGy

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D148275
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@HerrCai0907
HerrCai0907 committed Apr 17, 2023
1 parent beefca7 commit ee3a260
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Showing 2 changed files with 24 additions and 27 deletions.
15 changes: 15 additions & 0 deletions llvm/lib/Analysis/InstructionSimplify.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4582,6 +4582,21 @@ static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
return FalseVal;
}

if (Pred == ICmpInst::Predicate::ICMP_EQ) {
Value *X;
Value *Y;
// select(X | Y == 0, X or Y, X | Y) -> X | Y
if (match(CondVal, m_ICmp(Pred, m_Specific(FalseVal), m_Zero())) &&
match(FalseVal, m_Or(m_Value(X), m_Value(Y))) &&
(TrueVal == X || TrueVal == Y))
return FalseVal;
// select(X & Y == -1, X or Y, X & Y) -> X & Y
if (match(CondVal, m_ICmp(Pred, m_Specific(FalseVal), m_AllOnes())) &&
match(FalseVal, m_And(m_Value(X), m_Value(Y))) &&
(TrueVal == X || TrueVal == Y))
return FalseVal;
}

return nullptr;
}

Expand Down
36 changes: 9 additions & 27 deletions llvm/test/Transforms/InstSimplify/select_or_and.ll
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,9 +5,7 @@
define i32 @select_or_1(i32 %x, i32 %y) {
; CHECK-LABEL: @select_or_1(
; CHECK-NEXT: [[OR:%.*]] = or i32 [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[OR]], 0
; CHECK-NEXT: [[RET:%.*]] = select i1 [[CMP]], i32 [[X]], i32 [[OR]]
; CHECK-NEXT: ret i32 [[RET]]
; CHECK-NEXT: ret i32 [[OR]]
;
%or = or i32 %y, %x
%cmp = icmp eq i32 %or, 0
Expand All @@ -19,9 +17,7 @@ define i32 @select_or_1(i32 %x, i32 %y) {
define i32 @select_or_2(i32 %x, i32 %y) {
; CHECK-LABEL: @select_or_2(
; CHECK-NEXT: [[OR:%.*]] = or i32 [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[OR]], 0
; CHECK-NEXT: [[RET:%.*]] = select i1 [[CMP]], i32 [[Y]], i32 [[OR]]
; CHECK-NEXT: ret i32 [[RET]]
; CHECK-NEXT: ret i32 [[OR]]
;
%or = or i32 %y, %x
%cmp = icmp eq i32 %or, 0
Expand All @@ -33,9 +29,7 @@ define i32 @select_or_2(i32 %x, i32 %y) {
define i32 @select_or_3(i32 %x, i32 %y) {
; CHECK-LABEL: @select_or_3(
; CHECK-NEXT: [[OR:%.*]] = or i32 [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[OR]], 0
; CHECK-NEXT: [[RET:%.*]] = select i1 [[CMP]], i32 [[OR]], i32 [[X]]
; CHECK-NEXT: ret i32 [[RET]]
; CHECK-NEXT: ret i32 [[OR]]
;
%or = or i32 %y, %x
%cmp = icmp ne i32 %or, 0
Expand All @@ -47,9 +41,7 @@ define i32 @select_or_3(i32 %x, i32 %y) {
define i32 @select_or_4(i32 %x, i32 %y) {
; CHECK-LABEL: @select_or_4(
; CHECK-NEXT: [[OR:%.*]] = or i32 [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[OR]], 0
; CHECK-NEXT: [[RET:%.*]] = select i1 [[CMP]], i32 [[OR]], i32 [[Y]]
; CHECK-NEXT: ret i32 [[RET]]
; CHECK-NEXT: ret i32 [[OR]]
;
%or = or i32 %y, %x
%cmp = icmp ne i32 %or, 0
Expand All @@ -61,9 +53,7 @@ define i32 @select_or_4(i32 %x, i32 %y) {
define <4 x i32> @select_or_vec(<4 x i32> %x, <4 x i32> %y) {
; CHECK-LABEL: @select_or_vec(
; CHECK-NEXT: [[OR:%.*]] = or <4 x i32> [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ne <4 x i32> [[OR]], zeroinitializer
; CHECK-NEXT: [[RET:%.*]] = select <4 x i1> [[CMP]], <4 x i32> [[OR]], <4 x i32> [[Y]]
; CHECK-NEXT: ret <4 x i32> [[RET]]
; CHECK-NEXT: ret <4 x i32> [[OR]]
;
%or = or <4 x i32> %y, %x
%cmp = icmp ne <4 x i32> %or, zeroinitializer
Expand Down Expand Up @@ -115,9 +105,7 @@ define i32 @select_or_not_3(i32 %x, i32 %y) {
define i32 @select_and_1(i32 %x, i32 %y) {
; CHECK-LABEL: @select_and_1(
; CHECK-NEXT: [[AND:%.*]] = and i32 [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[AND]], -1
; CHECK-NEXT: [[RET:%.*]] = select i1 [[CMP]], i32 [[X]], i32 [[AND]]
; CHECK-NEXT: ret i32 [[RET]]
; CHECK-NEXT: ret i32 [[AND]]
;
%and = and i32 %y, %x
%cmp = icmp eq i32 %and, -1
Expand All @@ -129,9 +117,7 @@ define i32 @select_and_1(i32 %x, i32 %y) {
define i32 @select_and_2(i32 %x, i32 %y) {
; CHECK-LABEL: @select_and_2(
; CHECK-NEXT: [[AND:%.*]] = and i32 [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[AND]], -1
; CHECK-NEXT: [[RET:%.*]] = select i1 [[CMP]], i32 [[Y]], i32 [[AND]]
; CHECK-NEXT: ret i32 [[RET]]
; CHECK-NEXT: ret i32 [[AND]]
;
%and = and i32 %y, %x
%cmp = icmp eq i32 %and, -1
Expand All @@ -144,9 +130,7 @@ define i32 @select_and_2(i32 %x, i32 %y) {
define i32 @select_and_3(i32 %x, i32 %y) {
; CHECK-LABEL: @select_and_3(
; CHECK-NEXT: [[AND:%.*]] = and i32 [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[AND]], -1
; CHECK-NEXT: [[RET:%.*]] = select i1 [[CMP]], i32 [[AND]], i32 [[X]]
; CHECK-NEXT: ret i32 [[RET]]
; CHECK-NEXT: ret i32 [[AND]]
;
%and = and i32 %y, %x
%cmp = icmp ne i32 %and, -1
Expand All @@ -158,9 +142,7 @@ define i32 @select_and_3(i32 %x, i32 %y) {
define i32 @select_and_4(i32 %x, i32 %y) {
; CHECK-LABEL: @select_and_4(
; CHECK-NEXT: [[AND:%.*]] = and i32 [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[AND]], -1
; CHECK-NEXT: [[RET:%.*]] = select i1 [[CMP]], i32 [[AND]], i32 [[Y]]
; CHECK-NEXT: ret i32 [[RET]]
; CHECK-NEXT: ret i32 [[AND]]
;
%and = and i32 %y, %x
%cmp = icmp ne i32 %and, -1
Expand Down

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