Re-land "[WinEH] Add an EH registration and state insertion pass for 32-bit x86"

This reverts commit r236360.

This change exposed a bug in WinEHPrepare by opting win32 code into EH
preparation. We already knew that WinEHPrepare has bugs, and is the
status quo for x64, so I don't think that's a reason to hold off on this
change. I disabled exceptions in the sanitizer tests in r236505 and an
earlier revision.

llvm-svn: 236508

1 files changed, 317 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86WinEHState.cpp b/llvm/lib/Target/X86/X86WinEHState.cpp
new file mode 100644
index 0000000..e4bbffc
--- /dev/null
+++ b/llvm/lib/Target/X86/X86WinEHState.cpp
@@ -0,0 +1,317 @@
+//===-- X86WinEHState - Insert EH state updates for win32 exceptions ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// All functions using an MSVC EH personality use an explicitly updated state
+// number stored in an exception registration stack object. The registration
+// object is linked into a thread-local chain of registrations stored at fs:00.
+// This pass adds the registration object and EH state updates.
+//
+//===----------------------------------------------------------------------===//
+
+#include "X86.h"
+#include "llvm/Analysis/LibCallSemantics.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/WinEHFuncInfo.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/PatternMatch.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Transforms/Utils/Local.h"
+
+using namespace llvm;
+using namespace llvm::PatternMatch;
+
+#define DEBUG_TYPE "winehstate"
+
+namespace {
+class WinEHStatePass : public FunctionPass {
+public:
+  static char ID; // Pass identification, replacement for typeid.
+
+  WinEHStatePass() : FunctionPass(ID) {}
+
+  bool runOnFunction(Function &Fn) override;
+
+  bool doInitialization(Module &M) override;
+
+  bool doFinalization(Module &M) override;
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+  const char *getPassName() const override {
+    return "Windows 32-bit x86 EH state insertion";
+  }
+
+private:
+  void emitExceptionRegistrationRecord(Function *F);
+
+  void linkExceptionRegistration(IRBuilder<> &Builder, Value *RegNode,
+                                 Value *Handler);
+  void unlinkExceptionRegistration(IRBuilder<> &Builder, Value *RegNode);
+
+  // Module-level type getters.
+  Type *getEHRegistrationType();
+  Type *getSEH3RegistrationType();
+  Type *getSEH4RegistrationType();
+  Type *getCXXEH3RegistrationType();
+
+  // Per-module data.
+  Module *TheModule = nullptr;
+  StructType *EHRegistrationTy = nullptr;
+  StructType *CXXEH3RegistrationTy = nullptr;
+  StructType *SEH3RegistrationTy = nullptr;
+  StructType *SEH4RegistrationTy = nullptr;
+
+  // Per-function state
+  EHPersonality Personality = EHPersonality::Unknown;
+  Function *PersonalityFn = nullptr;
+};
+}
+
+FunctionPass *llvm::createX86WinEHStatePass() { return new WinEHStatePass(); }
+
+char WinEHStatePass::ID = 0;
+
+bool WinEHStatePass::doInitialization(Module &M) {
+  TheModule = &M;
+  return false;
+}
+
+bool WinEHStatePass::doFinalization(Module &M) {
+  assert(TheModule == &M);
+  TheModule = nullptr;
+  EHRegistrationTy = nullptr;
+  CXXEH3RegistrationTy = nullptr;
+  SEH3RegistrationTy = nullptr;
+  SEH4RegistrationTy = nullptr;
+  return false;
+}
+
+void WinEHStatePass::getAnalysisUsage(AnalysisUsage &AU) const {
+  // This pass should only insert a stack allocation, memory accesses, and
+  // framerecovers.
+  AU.setPreservesCFG();
+}
+
+bool WinEHStatePass::runOnFunction(Function &F) {
+  // Check the personality. Do nothing if this is not an MSVC personality.
+  LandingPadInst *LP = nullptr;
+  for (BasicBlock &BB : F) {
+    LP = BB.getLandingPadInst();
+    if (LP)
+      break;
+  }
+  if (!LP)
+    return false;
+  PersonalityFn =
+      dyn_cast<Function>(LP->getPersonalityFn()->stripPointerCasts());
+  if (!PersonalityFn)
+    return false;
+  Personality = classifyEHPersonality(PersonalityFn);
+  if (!isMSVCEHPersonality(Personality))
+    return false;
+
+  emitExceptionRegistrationRecord(&F);
+  // FIXME: State insertion.
+
+  // Reset per-function state.
+  PersonalityFn = nullptr;
+  Personality = EHPersonality::Unknown;
+  return true;
+}
+
+/// Get the common EH registration subobject:
+///   struct EHRegistrationNode {
+///     EHRegistrationNode *Next;
+///     EXCEPTION_DISPOSITION (*Handler)(...);
+///   };
+Type *WinEHStatePass::getEHRegistrationType() {
+  if (EHRegistrationTy)
+    return EHRegistrationTy;
+  LLVMContext &Context = TheModule->getContext();
+  EHRegistrationTy = StructType::create(Context, "EHRegistrationNode");
+  Type *FieldTys[] = {
+      EHRegistrationTy->getPointerTo(0), // EHRegistrationNode *Next
+      Type::getInt8PtrTy(Context) // EXCEPTION_DISPOSITION (*Handler)(...)
+  };
+  EHRegistrationTy->setBody(FieldTys, false);
+  return EHRegistrationTy;
+}
+
+/// The __CxxFrameHandler3 registration node:
+///   struct CXXExceptionRegistration {
+///     void *SavedESP;
+///     EHRegistrationNode SubRecord;
+///     int32_t TryLevel;
+///   };
+Type *WinEHStatePass::getCXXEH3RegistrationType() {
+  if (CXXEH3RegistrationTy)
+    return CXXEH3RegistrationTy;
+  LLVMContext &Context = TheModule->getContext();
+  Type *FieldTys[] = {
+      Type::getInt8PtrTy(Context), // void *SavedESP
+      getEHRegistrationType(),     // EHRegistrationNode SubRecord
+      Type::getInt32Ty(Context)    // int32_t TryLevel
+  };
+  CXXEH3RegistrationTy =
+      StructType::create(FieldTys, "CXXExceptionRegistration");
+  return CXXEH3RegistrationTy;
+}
+
+/// The _except_handler3 registration node:
+///   struct EH3ExceptionRegistration {
+///     EHRegistrationNode SubRecord;
+///     void *ScopeTable;
+///     int32_t TryLevel;
+///   };
+Type *WinEHStatePass::getSEH3RegistrationType() {
+  if (SEH3RegistrationTy)
+    return SEH3RegistrationTy;
+  LLVMContext &Context = TheModule->getContext();
+  Type *FieldTys[] = {
+      getEHRegistrationType(),     // EHRegistrationNode SubRecord
+      Type::getInt8PtrTy(Context), // void *ScopeTable
+      Type::getInt32Ty(Context)    // int32_t TryLevel
+  };
+  SEH3RegistrationTy = StructType::create(FieldTys, "EH3ExceptionRegistration");
+  return SEH3RegistrationTy;
+}
+
+/// The _except_handler4 registration node:
+///   struct EH4ExceptionRegistration {
+///     void *SavedESP;
+///     _EXCEPTION_POINTERS *ExceptionPointers;
+///     EHRegistrationNode SubRecord;
+///     int32_t EncodedScopeTable;
+///     int32_t TryLevel;
+///   };
+Type *WinEHStatePass::getSEH4RegistrationType() {
+  if (SEH4RegistrationTy)
+    return SEH4RegistrationTy;
+  LLVMContext &Context = TheModule->getContext();
+  Type *FieldTys[] = {
+      Type::getInt8PtrTy(Context), // void *SavedESP
+      Type::getInt8PtrTy(Context), // void *ExceptionPointers
+      getEHRegistrationType(),     // EHRegistrationNode SubRecord
+      Type::getInt32Ty(Context),   // int32_t EncodedScopeTable
+      Type::getInt32Ty(Context)    // int32_t TryLevel
+  };
+  SEH4RegistrationTy = StructType::create(FieldTys, "EH4ExceptionRegistration");
+  return SEH4RegistrationTy;
+}
+
+// Emit an exception registration record. These are stack allocations with the
+// common subobject of two pointers: the previous registration record (the old
+// fs:00) and the personality function for the current frame. The data before
+// and after that is personality function specific.
+void WinEHStatePass::emitExceptionRegistrationRecord(Function *F) {
+  assert(Personality == EHPersonality::MSVC_CXX ||
+         Personality == EHPersonality::MSVC_X86SEH);
+
+  StringRef PersonalityName = PersonalityFn->getName();
+  IRBuilder<> Builder(&F->getEntryBlock(), F->getEntryBlock().begin());
+  Type *Int8PtrType = Builder.getInt8PtrTy();
+  Value *SubRecord = nullptr;
+  if (PersonalityName == "__CxxFrameHandler3") {
+    Type *RegNodeTy = getCXXEH3RegistrationType();
+    Value *RegNode = Builder.CreateAlloca(RegNodeTy);
+    // FIXME: We can skip this in -GS- mode, when we figure that out.
+    // SavedESP = llvm.stacksave()
+    Value *SP = Builder.CreateCall(
+        Intrinsic::getDeclaration(TheModule, Intrinsic::stacksave));
+    Builder.CreateStore(SP, Builder.CreateStructGEP(RegNodeTy, RegNode, 0));
+    // TryLevel = -1
+    Builder.CreateStore(Builder.getInt32(-1),
+                        Builder.CreateStructGEP(RegNodeTy, RegNode, 2));
+    // FIXME: 'Personality' is incorrect here. We need to generate a trampoline
+    // that effectively gets the LSDA.
+    SubRecord = Builder.CreateStructGEP(RegNodeTy, RegNode, 1);
+    linkExceptionRegistration(Builder, SubRecord, PersonalityFn);
+  } else if (PersonalityName == "_except_handler3") {
+    Type *RegNodeTy = getSEH3RegistrationType();
+    Value *RegNode = Builder.CreateAlloca(RegNodeTy);
+    // TryLevel = -1
+    Builder.CreateStore(Builder.getInt32(-1),
+                        Builder.CreateStructGEP(RegNodeTy, RegNode, 2));
+    // FIXME: Generalize llvm.eh.sjljl.lsda for this.
+    // ScopeTable = nullptr
+    Builder.CreateStore(Constant::getNullValue(Int8PtrType),
+                        Builder.CreateStructGEP(RegNodeTy, RegNode, 1));
+    SubRecord = Builder.CreateStructGEP(RegNodeTy, RegNode, 0);
+    linkExceptionRegistration(Builder, SubRecord, PersonalityFn);
+  } else if (PersonalityName == "_except_handler4") {
+    Type *RegNodeTy = getSEH4RegistrationType();
+    Value *RegNode = Builder.CreateAlloca(RegNodeTy);
+    // SavedESP = llvm.stacksave()
+    Value *SP = Builder.CreateCall(
+        Intrinsic::getDeclaration(TheModule, Intrinsic::stacksave));
+    Builder.CreateStore(SP, Builder.CreateStructGEP(RegNodeTy, RegNode, 0));
+    // TryLevel = -2
+    Builder.CreateStore(Builder.getInt32(-2),
+                        Builder.CreateStructGEP(RegNodeTy, RegNode, 4));
+    // FIXME: Generalize llvm.eh.sjljl.lsda for this, and then do the stack
+    // cookie xor.
+    // ScopeTable = nullptr
+    Builder.CreateStore(Builder.getInt32(0),
+                        Builder.CreateStructGEP(RegNodeTy, RegNode, 3));
+    SubRecord = Builder.CreateStructGEP(RegNodeTy, RegNode, 2);
+    linkExceptionRegistration(Builder, SubRecord, PersonalityFn);
+  } else {
+    llvm_unreachable("unexpected personality function");
+  }
+
+  // FIXME: Insert an unlink before all returns.
+  for (BasicBlock &BB : *F) {
+    TerminatorInst *T = BB.getTerminator();
+    if (!isa<ReturnInst>(T))
+      continue;
+    Builder.SetInsertPoint(T);
+    unlinkExceptionRegistration(Builder, SubRecord);
+  }
+}
+
+void WinEHStatePass::linkExceptionRegistration(IRBuilder<> &Builder,
+                                               Value *RegNode, Value *Handler) {
+  Type *RegNodeTy = getEHRegistrationType();
+  // Handler = Handler
+  Handler = Builder.CreateBitCast(Handler, Builder.getInt8PtrTy());
+  Builder.CreateStore(Handler, Builder.CreateStructGEP(RegNodeTy, RegNode, 1));
+  // Next = [fs:00]
+  Constant *FSZero =
+      Constant::getNullValue(RegNodeTy->getPointerTo()->getPointerTo(257));
+  Value *Next = Builder.CreateLoad(FSZero);
+  Builder.CreateStore(Next, Builder.CreateStructGEP(RegNodeTy, RegNode, 0));
+  // [fs:00] = RegNode
+  Builder.CreateStore(RegNode, FSZero);
+}
+
+void WinEHStatePass::unlinkExceptionRegistration(IRBuilder<> &Builder,
+                                                 Value *RegNode) {
+  // Clone RegNode into the current BB for better address mode folding.
+  if (auto *GEP = dyn_cast<GetElementPtrInst>(RegNode)) {
+    GEP = cast<GetElementPtrInst>(GEP->clone());
+    Builder.Insert(GEP);
+    RegNode = GEP;
+  }
+  Type *RegNodeTy = getEHRegistrationType();
+  // [fs:00] = RegNode->Next
+  Value *Next =
+      Builder.CreateLoad(Builder.CreateStructGEP(RegNodeTy, RegNode, 0));
+  Constant *FSZero =
+      Constant::getNullValue(RegNodeTy->getPointerTo()->getPointerTo(257));
+  Builder.CreateStore(Next, FSZero);
+}