Fix bug in exception table allocation (PR13678)

Patch by Michael Muller.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172214 91177308-0d34-0410-b5e6-96231b3b80d8

lib/ExecutionEngine/JIT/JITEmitter.cpp

@@ -969,14 +969,24 @@ bool JITEmitter::finishFunction(MachineFunction &F) {
     SavedBufferBegin = BufferBegin;
     SavedBufferEnd = BufferEnd;
     SavedCurBufferPtr = CurBufferPtr;
+    uint8_t *FrameRegister;
 
-    BufferBegin = CurBufferPtr = MemMgr->startExceptionTable(F.getFunction(),
+    while (true) {
-                                                             ActualSize);
+      BufferBegin = CurBufferPtr = MemMgr->startExceptionTable(F.getFunction(),
-    BufferEnd = BufferBegin+ActualSize;
+                                                               ActualSize);
-    EmittedFunctions[F.getFunction()].ExceptionTable = BufferBegin;
+      BufferEnd = BufferBegin+ActualSize;
-    uint8_t *EhStart;
+      EmittedFunctions[F.getFunction()].ExceptionTable = BufferBegin;
-    uint8_t *FrameRegister = DE->EmitDwarfTable(F, *this, FnStart, FnEnd,
+      uint8_t *EhStart;
-                                                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;

unittests/ExecutionEngine/JIT/JITTest.cpp

@@ -161,7 +161,7 @@ public:
     uintptr_t ActualSizeResult;
   };
   std::vector<StartExceptionTableCall> startExceptionTableCalls;
-  virtual uint8_t* startExceptionTable(const Function* F,
+  virtual uint8_t *startExceptionTable(const Function *F,
                                        uintptr_t &ActualSize) {
     uintptr_t InitialActualSize = ActualSize;
     uint8_t *Result = Base->startExceptionTable(F, ActualSize);
@@ -203,14 +203,21 @@ bool LoadAssemblyInto(Module *M, const char *assembly) {
 
 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;
   }
 
@@ -297,6 +304,46 @@ TEST(JIT, GlobalInFunction) {
 
 #endif // !defined(__arm__) && !defined(__powerpc__)
 
+// 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;
 }