[llvm-commits] Fwd: Re: [LLVMdev] [PATCH] Fix for bug in JIT exception table allocation
Michael Muller
mmuller at enduden.com
Mon Sep 24 08:21:00 PDT 2012
Pinging again, more loudly :-)
Michael Muller wrote:
>
> Ping. (looking for someone to review or commit this, thanks)
>
> Michael Muller wrote:
> >
> > Thanks, Duncan -
> >
> > > Hi Michael,
> > >
> > > > --- lib/ExecutionEngine/JIT/JITEmitter.cpp (revision 163478)
> > > > +++ lib/ExecutionEngine/JIT/JITEmitter.cpp (working copy)
> > > > @@ -974,14 +974,24 @@
> > > > SavedBufferBegin = BufferBegin;
> > > > SavedBufferEnd = BufferEnd;
> > > > SavedCurBufferPtr = CurBufferPtr;
> > > > + uint8_t *FrameRegister;
> > > >
> > > > - BufferBegin = CurBufferPtr =
> > > > MemMgr->startExceptionTable(F.getFunction(),
> > > > - ActualSize);
> > > > - BufferEnd = BufferBegin+ActualSize;
> > > > - EmittedFunctions[F.getFunction()].ExceptionTable = BufferBegin;
> > > > - uint8_t *EhStart;
> > > > - uint8_t *FrameRegister = DE->EmitDwarfTable(F, *this, FnStart, FnEnd,
> > > > - EhStart);
> > > > + while (true) {
> > > > + BufferBegin = CurBufferPtr =
> > > > MemMgr->startExceptionTable(F.getFunction(),
> > > > +
> > > > ActualSize);
> > > > + BufferEnd = BufferBegin+ActualSize;
> > > > + EmittedFunctions[F.getFunction()].ExceptionTable = BufferBegin;
> > > > + uint8_t *EhStart;
> > > > + FrameRegister = DE->EmitDwarfTable(F, *this, FnStart, FnEnd,
> > > > EhStart);
> > > > +
> > > > + // If we've run out of memory, try again with twice as much space.
> > > > + if (CurBufferPtr == BufferEnd) {
> > > > + ActualSize = (CurBufferPtr-BufferBegin)*2;
> > > > + MemMgr->deallocateExceptionTable(BufferBegin);
> > > > + } else {
> > > > + break;
> > > > + }
> > >
> > > here I think it would be more conformant with LLVM style to do:
> > >
> > > // If the buffer was large enough to hold the table then we are
> > > done.
> > > if (CurBufferPtr != BufferEnd)
> > > break;
> > >
> > > // Try again with twice as much space.
> > > ActualSize = (CurBufferPtr-BufferBegin)*2;
> > > MemMgr->deallocateExceptionTable(BufferBegin);
> >
> > Done. New patch attached.
> >
> > >
> > > Otherwise looks good to me, though that's not saying much since I don't know
> > > this part of LLVM.
> >
> >
> > It looks like that code segment has been touched by a number of people:
> >
> >
> > 147615 rafael if (JITExceptionHandling) {
> > 49924 geoffray uintptr_t ActualSize = 0;
> > 91464 jyasskin SavedBufferBegin = BufferBegin;
> > 91464 jyasskin SavedBufferEnd = BufferEnd;
> > 91464 jyasskin SavedCurBufferPtr = CurBufferPtr;
> > 82418 rnk
> > 47079 geoffray BufferBegin = CurBufferPtr =
> > MemMgr->startExceptionTable(F.getFunction(),
> > 47079 geoffray
> > ActualSize);
> > 47079 geoffray BufferEnd = BufferBegin+ActualSize;
> > 84651 jyasskin EmittedFunctions[F.getFunction()].ExceptionTable =
> > BufferBegin;
> > 82418 rnk uint8_t *EhStart;
> > 82418 rnk uint8_t *FrameRegister = DE->EmitDwarfTable(F, *this,
> > FnStart, FnEnd,
> > 82418 rnk EhStart);
> > 48019 lattner MemMgr->endExceptionTable(F.getFunction(), BufferBegin,
> > CurBufferPtr,
> > 48019 lattner FrameRegister);
> > 91464 jyasskin BufferBegin = SavedBufferBegin;
> > 91464 jyasskin BufferEnd = SavedBufferEnd;
> > 91464 jyasskin CurBufferPtr = SavedCurBufferPtr;
> > 47079 geoffray
> > 102865 baldrick if (JITExceptionHandling) {
> > 127047 echristo TheJIT->RegisterTable(F.getFunction(), FrameRegister);
> > 82418 rnk }
> > 47079 geoffray }
> >
> > Any suggestions as to who would be the best qualified to look at it?
> >
> >
> > >
> > > Ciao, Duncan.
> > >
> > > > + }
> > > > MemMgr->endExceptionTable(F.getFunction(), BufferBegin, CurBufferPtr,
> > > > FrameRegister);
> > > > BufferBegin = SavedBufferBegin;
> >
> >
> > =============================================================================
> > michaelMuller = mmuller at enduden.com | http://www.mindhog.net/~mmuller
> > -----------------------------------------------------------------------------
> > Government is not reason, it is not eloquence; it is force. Like fire, it
> > is a dangerous servant and a fearsome master. - George Washington
> > =============================================================================
>
>
> =============================================================================
> michaelMuller = mmuller at enduden.com | http://www.mindhog.net/~mmuller
> -----------------------------------------------------------------------------
> Government is not reason, it is not eloquence; it is force. Like fire, it
> is a dangerous servant and a fearsome master. - George Washington
> =============================================================================
>
=============================================================================
michaelMuller = mmuller at enduden.com | http://www.mindhog.net/~mmuller
-----------------------------------------------------------------------------
Lokah Samasta Sukhino Bhavantu - May all beings everywhere be happy and free.
And may my own thoughts and actions contribute to that happiness and freedom.
=============================================================================
-------------- next part --------------
Index: unittests/ExecutionEngine/JIT/JITTest.cpp
===================================================================
--- unittests/ExecutionEngine/JIT/JITTest.cpp (revision 163809)
+++ unittests/ExecutionEngine/JIT/JITTest.cpp (working copy)
@@ -203,14 +203,21 @@
class JITTest : public testing::Test {
protected:
+ virtual RecordingJITMemoryManager* CreateMemoryManager() {
+ return new RecordingJITMemoryManager;
+ }
+
virtual void SetUp() {
M = new Module("<main>", Context);
- RJMM = new RecordingJITMemoryManager;
+ RJMM = CreateMemoryManager();
RJMM->setPoisonMemory(true);
std::string Error;
+ TargetOptions Options;
+ Options.JITExceptionHandling = true;
TheJIT.reset(EngineBuilder(M).setEngineKind(EngineKind::JIT)
.setJITMemoryManager(RJMM)
- .setErrorStr(&Error).create());
+ .setErrorStr(&Error)
+ .setTargetOptions(Options).create());
ASSERT_TRUE(TheJIT.get() != NULL) << Error;
}
@@ -292,6 +299,46 @@
EXPECT_EQ(3, *GPtr);
}
+// Regression test for a bug. The JITEmitter wasn't checking to verify that
+// it hadn't run out of space while generating the DWARF exception information
+// for an emitted function.
+
+class ExceptionMemoryManagerMock : public RecordingJITMemoryManager {
+ public:
+ virtual uint8_t* startExceptionTable(const Function* F,
+ uintptr_t &ActualSize) {
+ // force an insufficient size the first time through.
+ bool ChangeActualSize = false;
+ if (ActualSize == 0)
+ ChangeActualSize = true;;
+ uint8_t* result =
+ RecordingJITMemoryManager::startExceptionTable(F, ActualSize);
+ if (ChangeActualSize)
+ ActualSize = 1;
+ return result;
+ }
+};
+
+class JITExceptionMemoryTest : public JITTest {
+ protected:
+ virtual RecordingJITMemoryManager* CreateMemoryManager() {
+ return new ExceptionMemoryManagerMock;
+ }
+};
+
+TEST_F(JITExceptionMemoryTest, ExceptionTableOverflow) {
+ Function *F = Function::Create(TypeBuilder<void(void), false>::get(Context),
+ Function::ExternalLinkage,
+ "func1", M);
+ BasicBlock *Block = BasicBlock::Create(Context, "block", F);
+ IRBuilder<> Builder(Block);
+ Builder.CreateRetVoid();
+ TheJIT->getPointerToFunction(F);
+ ASSERT_TRUE(RJMM->startExceptionTableCalls.size() == 2);
+ ASSERT_TRUE(RJMM->deallocateExceptionTableCalls.size() == 1);
+ ASSERT_TRUE(RJMM->endExceptionTableCalls.size() == 1);
+}
+
int PlusOne(int arg) {
return arg + 1;
}
Index: lib/ExecutionEngine/JIT/JITEmitter.cpp
===================================================================
--- lib/ExecutionEngine/JIT/JITEmitter.cpp (revision 163809)
+++ lib/ExecutionEngine/JIT/JITEmitter.cpp (working copy)
@@ -974,14 +974,24 @@
SavedBufferBegin = BufferBegin;
SavedBufferEnd = BufferEnd;
SavedCurBufferPtr = CurBufferPtr;
+ uint8_t *FrameRegister;
- BufferBegin = CurBufferPtr = MemMgr->startExceptionTable(F.getFunction(),
- ActualSize);
- BufferEnd = BufferBegin+ActualSize;
- EmittedFunctions[F.getFunction()].ExceptionTable = BufferBegin;
- uint8_t *EhStart;
- uint8_t *FrameRegister = DE->EmitDwarfTable(F, *this, FnStart, FnEnd,
- EhStart);
+ while (true) {
+ BufferBegin = CurBufferPtr = MemMgr->startExceptionTable(F.getFunction(),
+ ActualSize);
+ BufferEnd = BufferBegin+ActualSize;
+ EmittedFunctions[F.getFunction()].ExceptionTable = BufferBegin;
+ uint8_t *EhStart;
+ FrameRegister = DE->EmitDwarfTable(F, *this, FnStart, FnEnd, EhStart);
+
+ // If the buffer was large enough to hold the table then we are done.
+ if (CurBufferPtr != BufferEnd)
+ break;
+
+ // Try again with twice as much space.
+ ActualSize = (CurBufferPtr-BufferBegin)*2;
+ MemMgr->deallocateExceptionTable(BufferBegin);
+ }
MemMgr->endExceptionTable(F.getFunction(), BufferBegin, CurBufferPtr,
FrameRegister);
BufferBegin = SavedBufferBegin;
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