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FastISel: do not fold a swifterror load into anything. #2631

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Merged
merged 1 commit into from
Mar 8, 2021
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FastISel: do not fold a swifterror load into anything. #2631

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6 changes: 6 additions & 0 deletions llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2413,6 +2413,12 @@ bool FastISel::tryToFoldLoad(const LoadInst *LI, const Instruction *FoldInst) {
if (LI->isVolatile())
return false;

// Swifterror loads are not actually loads.
if (auto AI = dyn_cast<AllocaInst>(LI->getPointerOperand())) {
if (AI->isSwiftError())
return false;
}

// Figure out which vreg this is going into. If there is no assigned vreg yet
// then there actually was no reference to it. Perhaps the load is referenced
// by a dead instruction.
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20 changes: 20 additions & 0 deletions llvm/test/CodeGen/X86/swifterror-O0.ll
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@@ -0,0 +1,20 @@
; RUN: llc -mtriple=x86_64-apple-darwin -O0 %s -o - | FileCheck %s

define i32 @foo() {
; CHECK-LABEL: foo:
; CHECK: cmpq $0, %r12

%swifterror = alloca swifterror i8*
call void @callee(i8** swifterror %swifterror)
%err = load i8*, i8** %swifterror
%tst = icmp ne i8* %err, null
br i1 %tst, label %true, label %false

true:
ret i32 0

false:
ret i32 1
}

declare void @callee(i8** swifterror)