1 files changed, 118 insertions, 0 deletions
diff --git a/lib/Transforms/NaCl/LowerEmExceptionsPass.cpp b/lib/Transforms/NaCl/LowerEmExceptionsPass.cpp
new file mode 100644
index 0000000000..3690537c4e
--- /dev/null
+++ b/lib/Transforms/NaCl/LowerEmExceptionsPass.cpp
@@ -0,0 +1,118 @@
+//===- LowerEmExceptions - Lower exceptions for Emscripten/JS   -----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This is based off the 'cheap' version of LowerInvoke. It does two things:
+//
+//  1) Lower
+//         invoke() to l1 unwind l2
+//     into
+//         preinvoke(); // (will clear __THREW__)
+//         call();
+//         threw = postinvoke(); (check __THREW__)
+//         br threw, l1, l2
+//
+//  2) Lower landingpads to return a single i8*, avoid the structural type
+//     which is unneeded anyhow.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/NaCl.h"
+
+using namespace llvm;
+
+namespace {
+  class LowerEmExceptions : public ModulePass {
+    Function *PreInvoke, *PostInvoke;
+    Module *TheModule;
+
+  public:
+    static char ID; // Pass identification, replacement for typeid
+    explicit LowerEmExceptions() : ModulePass(ID), PreInvoke(NULL), PostInvoke(NULL), TheModule(NULL) {
+      initializeLowerEmExceptionsPass(*PassRegistry::getPassRegistry());
+    }
+    bool runOnModule(Module &M);
+  };
+}
+
+char LowerEmExceptions::ID = 0;
+INITIALIZE_PASS(LowerEmExceptions, "loweremexceptions",
+                "Lower invoke and unwind for js/emscripten",
+                false, false)
+
+Instruction *getSingleUse(Instruction *I) {
+  Instruction *Ret = NULL;
+  for (Instruction::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE; ++UI) {
+    assert(Ret == NULL);
+    Ret = cast<ExtractElementInst>(*UI);
+  }
+  assert(Ret != NULL);
+  return Ret;
+}
+
+bool LowerEmExceptions::runOnModule(Module &M) {
+  TheModule = &M;
+
+  Type *Void = Type::getVoidTy(M.getContext());
+  Type *i32 = Type::getInt32Ty(M.getContext());
+
+  SmallVector<Type*, 0> ArgTypes;
+  FunctionType *VoidFunc = FunctionType::get(Void, ArgTypes, false);
+  FunctionType *IntFunc = FunctionType::get(i32, ArgTypes, false);
+
+  PreInvoke = Function::Create(VoidFunc, GlobalValue::ExternalLinkage, "preInvoke", TheModule);
+  PostInvoke = Function::Create(IntFunc, GlobalValue::ExternalLinkage, "postInvoke", TheModule);
+
+  bool Changed = false;
+
+  for (Module::iterator Iter = M.begin(), E = M.end(); Iter != E; ) {
+    Function *F = Iter++;
+    for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
+      if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
+        // Fix up the landingpad. First, make a copy returning just an integer
+        LandingPadInst *LP = II->getLandingPadInst();
+        unsigned Num = LP->getNumClauses();
+        LandingPadInst *NewLP = LandingPadInst::Create(i32, LP->getPersonalityFn(), Num, "", LP);
+        NewLP->setCleanup(LP->isCleanup());
+        for (unsigned i = 0; i < Num; i++) NewLP->addClause(LP->getClause(i));
+
+        // Next, replace the old LP's single use, which is an extractelement, to eliminate the ee's and use the value directly
+        ExtractElementInst *EE = cast<ExtractElementInst>(getSingleUse(LP));
+        EE->replaceAllUsesWith(NewLP);
+        EE->eraseFromParent();
+
+        // Finish the LP by replacing it
+        LP->replaceAllUsesWith(NewLP);
+        LP->eraseFromParent();
+
+        Changed = true;
+      }
+    }
+  }
+
+  return Changed;
+}
+
+ModulePass *llvm::createLowerEmExceptionsPass() {
+  return new LowerEmExceptions();
+}
+