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[InstCombine] Fold "extract (select (cond, insert(agg, elem), FV))" #115969

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[InstCombine] Fold "extract (select (cond, insert(agg, elem), FV))" #115969

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[InstCombine] Fold "extract (select (cond, insert(agg, elem), FV))"
weiguozhi Nov 13, 2024
f44cade
Add new test cases.
weiguozhi Nov 13, 2024
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20 changes: 19 additions & 1 deletion llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1692,7 +1692,25 @@ Instruction *InstCombinerImpl::FoldOpIntoSelect(Instruction &Op, SelectInst *SI,

Value *TV = SI->getTrueValue();
Value *FV = SI->getFalseValue();
if (!(isa<Constant>(TV) || isa<Constant>(FV)))
if ((Op.getOpcode() == Instruction::ExtractValue) &&
(isa<InsertValueInst>(TV) || isa<InsertValueInst>(FV))) {
// extract (select (cond, insert(agg, elem), FV))
// -> select (cond, elem, extract(FV))
ExtractValueInst *EV = dyn_cast<ExtractValueInst>(&Op);
Value *NewTV = simplifyExtractValueInst(TV, EV->getIndices(),
SQ.getWithInstruction(&Op));
Value *NewFV = simplifyExtractValueInst(FV, EV->getIndices(),
SQ.getWithInstruction(&Op));
if (!NewTV && !NewFV)
return nullptr;
Builder.SetInsertPoint(SI);
if (!NewTV)
NewTV = Builder.CreateExtractValue(TV, EV->getIndices());
if (!NewFV)
NewFV = Builder.CreateExtractValue(FV, EV->getIndices());
return SelectInst::Create(SI->getCondition(), NewTV, NewFV, "", nullptr,
SI);
} else if (!(isa<Constant>(TV) || isa<Constant>(FV)))
return nullptr;

// Bool selects with constant operands can be folded to logical ops.
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31 changes: 24 additions & 7 deletions llvm/test/Transforms/InstCombine/extract-select-agg.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -56,14 +56,9 @@ define void @test_select_agg_multiuse(i1 %cond, i64 %v1, i64 %v2, i64 %v3, i64 %
; CHECK-LABEL: define void @test_select_agg_multiuse(
; CHECK-SAME: i1 [[COND:%.*]], i64 [[V1:%.*]], i64 [[V2:%.*]], i64 [[V3:%.*]], i64 [[V4:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[A0:%.*]] = insertvalue { i64, i64 } poison, i64 [[V1]], 0
; CHECK-NEXT: [[A1:%.*]] = insertvalue { i64, i64 } [[A0]], i64 [[V2]], 1
; CHECK-NEXT: [[B0:%.*]] = insertvalue { i64, i64 } poison, i64 [[V3]], 0
; CHECK-NEXT: [[B1:%.*]] = insertvalue { i64, i64 } [[B0]], i64 [[V4]], 1
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[COND]], { i64, i64 } [[A1]], { i64, i64 } [[B1]]
; CHECK-NEXT: [[X:%.*]] = extractvalue { i64, i64 } [[SEL]], 0
; CHECK-NEXT: [[X:%.*]] = select i1 [[COND]], i64 [[V1]], i64 [[V3]]
; CHECK-NEXT: call void @use(i64 [[X]])
; CHECK-NEXT: [[Y:%.*]] = extractvalue { i64, i64 } [[SEL]], 1
; CHECK-NEXT: [[Y:%.*]] = select i1 [[COND]], i64 [[V2]], i64 [[V4]]
; CHECK-NEXT: call void @use(i64 [[Y]])
; CHECK-NEXT: ret void
;
Expand All @@ -81,3 +76,25 @@ entry:
}

declare void @use(i64)

define i64 @test_extract_select_insert(ptr %p1, i64 %v) {
; CHECK-LABEL: define i64 @test_extract_select_insert(
; CHECK-SAME: ptr [[P1:%.*]], i64 [[V:%.*]]) {
; CHECK-NEXT: [[CALL:%.*]] = call { ptr, i64 } @foo()
; CHECK-NEXT: [[ELM1:%.*]] = extractvalue { ptr, i64 } [[CALL]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[ELM1]], [[V]]
; CHECK-NEXT: [[TMP1:%.*]] = extractvalue { ptr, i64 } [[CALL]], 1
; CHECK-NEXT: [[RES:%.*]] = select i1 [[CMP]], i64 4294967294, i64 [[TMP1]]
; CHECK-NEXT: ret i64 [[RES]]
;
%call = call { ptr, i64 } @foo()
%elm1 = extractvalue { ptr, i64 } %call, 1
%cmp = icmp eq i64 %elm1, %v
%fca0 = insertvalue { ptr, i64 } poison, ptr %p1, 0
%fca1 = insertvalue { ptr, i64 } %fca0, i64 4294967294, 1
%select = select i1 %cmp, { ptr, i64 } %fca1, { ptr, i64 } %call
%res = extractvalue { ptr, i64 } %select, 1
ret i64 %res
}

declare { ptr, i64 } @foo()
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