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[WinEH] Update SplitAnalysis::computeLastSplitPoint to cope with multiple EH successors 

We didn't have logic to correctly handle CFGs where there was more than
one EH-pad successor (these are novel with WinEH).
There were situations where a register was live in one exceptional
successor but not another but the code as written would only consider
the first exceptional successor it found.

This resulted in split points which were insufficiently early if an
invoke was present.

This fixes PR27501.

N.B.  This removes getLandingPadSuccessor.

llvm-svn: 267412
This commit is contained in:
David Majnemer 2016-04-25 14:31:32 +00:00
parent 82d04260b7
commit dd21523653
5 changed files with 87 additions and 18 deletions
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8
llvm/include/llvm/ADT/STLExtras.h
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@ -383,6 +383,14 @@ bool any_of(R &&Range, UnaryPredicate &&P) {
std::forward<UnaryPredicate>(P));
}
/// Provide wrappers to std::none_of which take ranges instead of having to pass
/// begin/end explicitly.
template <typename R, class UnaryPredicate>
bool none_of(R &&Range, UnaryPredicate &&P) {
return std::none_of(Range.begin(), Range.end(),
std::forward<UnaryPredicate>(P));
}
/// Provide wrappers to std::find which take ranges instead of having to pass
/// begin/end explicitly.
template<typename R, class T>

4
llvm/include/llvm/CodeGen/MachineBasicBlock.h
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@ -342,10 +342,6 @@ public:
/// via an exception handler.
void setIsEHPad(bool V = true) { IsEHPad = V; }
/// If this block has a successor that is a landing pad, return it. Otherwise
/// return NULL.
const MachineBasicBlock *getLandingPadSuccessor() const;
bool hasEHPadSuccessor() const;
/// Returns true if this is the entry block of an EH funclet.

10
llvm/lib/CodeGen/MachineBasicBlock.cpp
View File

@ -198,16 +198,6 @@ MachineBasicBlock::iterator MachineBasicBlock::getLastNonDebugInstr() {
return end();
}
const MachineBasicBlock *MachineBasicBlock::getLandingPadSuccessor() const {
// A block with a landing pad successor only has one other successor.
if (succ_size() > 2)
return nullptr;
for (const_succ_iterator I = succ_begin(), E = succ_end(); I != E; ++I)
if ((*I)->isEHPad())
return *I;
return nullptr;
}
bool MachineBasicBlock::hasEHPadSuccessor() const {
for (const_succ_iterator I = succ_begin(), E = succ_end(); I != E; ++I)
if ((*I)->isEHPad())

16
llvm/lib/CodeGen/SplitKit.cpp
View File

@ -57,11 +57,14 @@ void SplitAnalysis::clear() {
SlotIndex SplitAnalysis::computeLastSplitPoint(unsigned Num) {
const MachineBasicBlock *MBB = MF.getBlockNumbered(Num);
// FIXME: Handle multiple EH pad successors.
const MachineBasicBlock *LPad = MBB->getLandingPadSuccessor();
std::pair<SlotIndex, SlotIndex> &LSP = LastSplitPoint[Num];
SlotIndex MBBEnd = LIS.getMBBEndIdx(MBB);
SmallVector<const MachineBasicBlock *, 1> EHPadSucessors;
for (const MachineBasicBlock *SMBB : MBB->successors())
if (SMBB->isEHPad())
EHPadSucessors.push_back(SMBB);
// Compute split points on the first call. The pair is independent of the
// current live interval.
if (!LSP.first.isValid()) {
@ -72,7 +75,7 @@ SlotIndex SplitAnalysis::computeLastSplitPoint(unsigned Num) {
LSP.first = LIS.getInstructionIndex(*FirstTerm);
// If there is a landing pad successor, also find the call instruction.
if (!LPad)
if (EHPadSucessors.empty())
return LSP.first;
// There may not be a call instruction (?) in which case we ignore LPad.
LSP.second = LSP.first;
@ -88,7 +91,12 @@ SlotIndex SplitAnalysis::computeLastSplitPoint(unsigned Num) {
// If CurLI is live into a landing pad successor, move the last split point
// back to the call that may throw.
if (!LPad || !LSP.second || !LIS.isLiveInToMBB(*CurLI, LPad))
if (!LSP.second)
return LSP.first;
if (none_of(EHPadSucessors, [&](const MachineBasicBlock *EHPad) {
return LIS.isLiveInToMBB(*CurLI, EHPad);
}))
return LSP.first;
// Find the value leaving MBB.

67
llvm/test/CodeGen/X86/pr27501.ll Normal file
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@ -0,0 +1,67 @@
; RUN: llc < %s | FileCheck %s
target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-windows-msvc"
define void @test1(i64* %result.repack) personality i32 (...)* @__CxxFrameHandler3 {
bb:
invoke void @may_throw(i32 1)
to label %postinvoke unwind label %cleanuppad
; CHECK: movl $1, %ecx
; CHECK: callq may_throw
postinvoke: ; preds = %bb
store i64 19, i64* %result.repack, align 8
; CHECK: movq $19, (%rsi)
; CHECK: movl $2, %ecx
; CHECK-NEXT: movq %rsi, -8(%rbp)
; CHECK-NEXT: callq may_throw
invoke void @may_throw(i32 2)
to label %assertFailed unwind label %catch.dispatch
catch.dispatch: ; preds = %cleanuppad9, %postinvoke
%tmp3 = catchswitch within none [label %catch.object.Throwable] unwind label %cleanuppad
catch.object.Throwable: ; preds = %catch.dispatch
%tmp2 = catchpad within %tmp3 [i8* null, i32 64, i8* null]
catchret from %tmp2 to label %catchhandler
catchhandler: ; preds = %catch.object.Throwable
invoke void @may_throw(i32 3)
to label %try.success.or.caught unwind label %cleanuppad
try.success.or.caught: ; preds = %catchhandler
invoke void @may_throw(i32 4)
to label %postinvoke27 unwind label %cleanuppad24
; CHECK: movl $4, %ecx
; CHECK-NEXT: callq may_throw
postinvoke27: ; preds = %try.success.or.caught
store i64 42, i64* %result.repack, align 8
; CHECK: movq -8(%rbp), %[[reload:r..]]
; CHECK-NEXT: movq $42, (%[[reload]])
ret void
cleanuppad24: ; preds = %try.success.or.caught
%tmp5 = cleanuppad within none []
cleanupret from %tmp5 unwind to caller
cleanuppad: ; preds = %catchhandler, %catch.dispatch, %bb
%tmp1 = cleanuppad within none []
cleanupret from %tmp1 unwind to caller
assertFailed: ; preds = %postinvoke
invoke void @may_throw(i32 5)
to label %postinvoke13 unwind label %cleanuppad9
postinvoke13: ; preds = %assertFailed
unreachable
cleanuppad9: ; preds = %assertFailed
%tmp4 = cleanuppad within none []
cleanupret from %tmp4 unwind label %catch.dispatch
}
declare void @may_throw(i32)
declare i32 @__CxxFrameHandler3(...)