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[WinEH] Emit the LSDA even if no lpads remain but outlining occurred

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The outlined funclets call intrinsics which reference labels from the
LSDA. This situation can easily arise in small functions with a single
cleanup at -O0, where Clang marks a definition as nounwind, and then
WinEHPrepare "discovers" that the landingpad is dead by accident and
deletes it.

We now need to ask the LLVM IR Function for it's personality directly,
rather than going through MachineModuleInfo.

Fixes PR23892.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242063 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Kleckner 2015-07-13 20:41:46 +00:00
parent 360ec4c35f
commit da9c587dad
2 changed files with 49 additions and 6 deletions
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20
lib/CodeGen/AsmPrinter/WinException.cpp
View File

@ -70,7 +70,9 @@ void WinException::beginFunction(const MachineFunction *MF) {
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
unsigned PerEncoding = TLOF.getPersonalityEncoding();
const Function *Per = MMI->getPersonality();
const Function *Per = nullptr;
if (F->hasPersonalityFn())
Per = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
shouldEmitPersonality = hasLandingPads &&
PerEncoding != dwarf::DW_EH_PE_omit && Per;
@ -79,10 +81,12 @@ void WinException::beginFunction(const MachineFunction *MF) {
shouldEmitLSDA = shouldEmitPersonality &&
LSDAEncoding != dwarf::DW_EH_PE_omit;
// If we're not using CFI, we don't want the CFI or the personality. Emit the
// LSDA if this is the parent function.
// If we're not using CFI, we don't want the CFI or the personality. If
// WinEHPrepare outlined something, we should emit the LSDA.
if (!Asm->MAI->usesWindowsCFI()) {
shouldEmitLSDA = (hasLandingPads && F == ParentF);
bool HasOutlinedChildren =
F->hasFnAttribute("wineh-parent") && F == ParentF;
shouldEmitLSDA = HasOutlinedChildren;
shouldEmitPersonality = false;
return;
}
@ -121,7 +125,10 @@ void WinException::endFunction(const MachineFunction *MF) {
if (!shouldEmitPersonality && !shouldEmitMoves && !shouldEmitLSDA)
return;
EHPersonality Per = MMI->getPersonalityType();
const Function *F = MF->getFunction();
EHPersonality Per = EHPersonality::Unknown;
if (F->hasPersonalityFn())
Per = classifyEHPersonality(F->getPersonalityFn());
// Get rid of any dead landing pads if we're not using a Windows EH scheme. In
// Windows EH schemes, the landing pad is not actually reachable. It only
@ -582,7 +589,8 @@ void WinException::emitExceptHandlerTable(const MachineFunction *MF) {
OS.EmitValueToAlignment(4);
OS.EmitLabel(LSDALabel);
const Function *Per = MMI->getPersonality();
const Function *Per =
dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
StringRef PerName = Per->getName();
int BaseState = -1;
if (PerName == "_except_handler4") {

35
test/CodeGen/X86/cppeh-nounwind.ll Normal file
View File

@ -0,0 +1,35 @@
; RUN: llc -mtriple=i686-pc-windows-msvc < %s | FileCheck %s
; Sometimes invokes of nounwind functions make it through to CodeGen, especially
; at -O0, where Clang sometimes optimistically annotates functions as nounwind.
; WinEHPrepare ends up outlining functions, and emitting references to LSDA
; labels. Make sure we emit the LSDA in that case.
declare i32 @__CxxFrameHandler3(...)
declare void @nounwind_func() nounwind
declare void @cleanup()
define void @should_emit_tables() personality i32 (...)* @__CxxFrameHandler3 {
entry:
invoke void @nounwind_func()
to label %done unwind label %lpad
done:
ret void
lpad:
%vals = landingpad { i8*, i32 }
cleanup
call void @cleanup()
resume { i8*, i32 } %vals
}
; CHECK: _should_emit_tables:
; CHECK: calll _nounwind_func
; CHECK: retl
; CHECK: L__ehtable$should_emit_tables:
; CHECK: ___ehhandler$should_emit_tables:
; CHECK: movl $L__ehtable$should_emit_tables, %eax
; CHECK: jmp ___CxxFrameHandler3 # TAILCALL