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[WebAssembly] Fix a bug deleting instruction in a ranged for loop 

Summary: We shouldn't delete elements while iterating a ranged for loop.

Reviewers: dschuff

Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58519

llvm-svn: 354844
This commit is contained in:
Heejin Ahn 2019-02-26 04:08:49 +00:00
parent f0d2733e50
commit d2a56ac661
2 changed files with 26 additions and 2 deletions
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8
llvm/lib/Target/WebAssembly/WebAssemblyLateEHPrepare.cpp
View File

@ -222,18 +222,22 @@ bool WebAssemblyLateEHPrepare::addExceptionExtraction(MachineFunction &MF) {
const auto &TII = *MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo();
auto *EHInfo = MF.getWasmEHFuncInfo();
SmallVector<MachineInstr *, 16> ExtractInstrs;
SmallVector<MachineInstr *, 8> ToDelete;
for (auto &MBB : MF) {
for (auto &MI : MBB) {
if (MI.getOpcode() == WebAssembly::EXTRACT_EXCEPTION_I32) {
if (MI.getOperand(0).isDead())
MI.eraseFromParent();
ToDelete.push_back(&MI);
else
ExtractInstrs.push_back(&MI);
}
}
}
bool Changed = !ToDelete.empty() || !ExtractInstrs.empty();
for (auto *MI : ToDelete)
MI->eraseFromParent();
if (ExtractInstrs.empty())
return false;
return Changed;
// Find terminate pads.
SmallSet<MachineBasicBlock *, 8> TerminatePads;

20
llvm/test/CodeGen/WebAssembly/exception.ll
View File

@ -340,6 +340,26 @@ try.cont: ; preds = %entry, %catch.start
ret void
}
; When the result of @llvm.wasm.get.exception is not used. This is created to
; fix a bug in LateEHPrepare and this should not crash.
define void @test_get_exception_wo_use() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
entry:
invoke void @foo()
to label %try.cont unwind label %catch.dispatch
catch.dispatch: ; preds = %entry
%0 = catchswitch within none [label %catch.start] unwind to caller
catch.start: ; preds = %catch.dispatch
%1 = catchpad within %0 [i8* null]
%2 = call i8* @llvm.wasm.get.exception(token %1)
%3 = call i32 @llvm.wasm.get.ehselector(token %1)
catchret from %1 to label %try.cont
try.cont: ; preds = %entry, %catch.start
ret void
}
declare void @foo()
declare void @bar(i32*)
declare i32 @__gxx_wasm_personality_v0(...)