llvm16 targets

1 files changed, 306 insertions, 0 deletions

diff --git a/contrib/libs/llvm16/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp b/contrib/libs/llvm16/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp
new file mode 100644
index 00000000000..b3fe110a092
--- /dev/null
+++ b/contrib/libs/llvm16/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp
@@ -0,0 +1,306 @@
+//===-- WebAssemblyFixFunctionBitcasts.cpp - Fix function bitcasts --------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Fix bitcasted functions.
+///
+/// WebAssembly requires caller and callee signatures to match, however in LLVM,
+/// some amount of slop is vaguely permitted. Detect mismatch by looking for
+/// bitcasts of functions and rewrite them to use wrapper functions instead.
+///
+/// This doesn't catch all cases, such as when a function's address is taken in
+/// one place and casted in another, but it works for many common cases.
+///
+/// Note that LLVM already optimizes away function bitcasts in common cases by
+/// dropping arguments as needed, so this pass only ends up getting used in less
+/// common cases.
+///
+//===----------------------------------------------------------------------===//
+
+#include "WebAssembly.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Operator.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "wasm-fix-function-bitcasts"
+
+namespace {
+class FixFunctionBitcasts final : public ModulePass {
+  StringRef getPassName() const override {
+    return "WebAssembly Fix Function Bitcasts";
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    ModulePass::getAnalysisUsage(AU);
+  }
+
+  bool runOnModule(Module &M) override;
+
+public:
+  static char ID;
+  FixFunctionBitcasts() : ModulePass(ID) {}
+};
+} // End anonymous namespace
+
+char FixFunctionBitcasts::ID = 0;
+INITIALIZE_PASS(FixFunctionBitcasts, DEBUG_TYPE,
+                "Fix mismatching bitcasts for WebAssembly", false, false)
+
+ModulePass *llvm::createWebAssemblyFixFunctionBitcasts() {
+  return new FixFunctionBitcasts();
+}
+
+// Recursively descend the def-use lists from V to find non-bitcast users of
+// bitcasts of V.
+static void findUses(Value *V, Function &F,
+                     SmallVectorImpl<std::pair<CallBase *, Function *>> &Uses) {
+  for (User *U : V->users()) {
+    if (auto *BC = dyn_cast<BitCastOperator>(U))
+      findUses(BC, F, Uses);
+    else if (auto *A = dyn_cast<GlobalAlias>(U))
+      findUses(A, F, Uses);
+    else if (auto *CB = dyn_cast<CallBase>(U)) {
+      Value *Callee = CB->getCalledOperand();
+      if (Callee != V)
+        // Skip calls where the function isn't the callee
+        continue;
+      if (CB->getFunctionType() == F.getValueType())
+        // Skip uses that are immediately called
+        continue;
+      Uses.push_back(std::make_pair(CB, &F));
+    }
+  }
+}
+
+// Create a wrapper function with type Ty that calls F (which may have a
+// different type). Attempt to support common bitcasted function idioms:
+//  - Call with more arguments than needed: arguments are dropped
+//  - Call with fewer arguments than needed: arguments are filled in with undef
+//  - Return value is not needed: drop it
+//  - Return value needed but not present: supply an undef
+//
+// If the all the argument types of trivially castable to one another (i.e.
+// I32 vs pointer type) then we don't create a wrapper at all (return nullptr
+// instead).
+//
+// If there is a type mismatch that we know would result in an invalid wasm
+// module then generate wrapper that contains unreachable (i.e. abort at
+// runtime).  Such programs are deep into undefined behaviour territory,
+// but we choose to fail at runtime rather than generate and invalid module
+// or fail at compiler time.  The reason we delay the error is that we want
+// to support the CMake which expects to be able to compile and link programs
+// that refer to functions with entirely incorrect signatures (this is how
+// CMake detects the existence of a function in a toolchain).
+//
+// For bitcasts that involve struct types we don't know at this stage if they
+// would be equivalent at the wasm level and so we can't know if we need to
+// generate a wrapper.
+static Function *createWrapper(Function *F, FunctionType *Ty) {
+  Module *M = F->getParent();
+
+  Function *Wrapper = Function::Create(Ty, Function::PrivateLinkage,
+                                       F->getName() + "_bitcast", M);
+  BasicBlock *BB = BasicBlock::Create(M->getContext(), "body", Wrapper);
+  const DataLayout &DL = BB->getModule()->getDataLayout();
+
+  // Determine what arguments to pass.
+  SmallVector<Value *, 4> Args;
+  Function::arg_iterator AI = Wrapper->arg_begin();
+  Function::arg_iterator AE = Wrapper->arg_end();
+  FunctionType::param_iterator PI = F->getFunctionType()->param_begin();
+  FunctionType::param_iterator PE = F->getFunctionType()->param_end();
+  bool TypeMismatch = false;
+  bool WrapperNeeded = false;
+
+  Type *ExpectedRtnType = F->getFunctionType()->getReturnType();
+  Type *RtnType = Ty->getReturnType();
+
+  if ((F->getFunctionType()->getNumParams() != Ty->getNumParams()) ||
+      (F->getFunctionType()->isVarArg() != Ty->isVarArg()) ||
+      (ExpectedRtnType != RtnType))
+    WrapperNeeded = true;
+
+  for (; AI != AE && PI != PE; ++AI, ++PI) {
+    Type *ArgType = AI->getType();
+    Type *ParamType = *PI;
+
+    if (ArgType == ParamType) {
+      Args.push_back(&*AI);
+    } else {
+      if (CastInst::isBitOrNoopPointerCastable(ArgType, ParamType, DL)) {
+        Instruction *PtrCast =
+            CastInst::CreateBitOrPointerCast(AI, ParamType, "cast");
+        PtrCast->insertInto(BB, BB->end());
+        Args.push_back(PtrCast);
+      } else if (ArgType->isStructTy() || ParamType->isStructTy()) {
+        LLVM_DEBUG(dbgs() << "createWrapper: struct param type in bitcast: "
+                          << F->getName() << "\n");
+        WrapperNeeded = false;
+      } else {
+        LLVM_DEBUG(dbgs() << "createWrapper: arg type mismatch calling: "
+                          << F->getName() << "\n");
+        LLVM_DEBUG(dbgs() << "Arg[" << Args.size() << "] Expected: "
+                          << *ParamType << " Got: " << *ArgType << "\n");
+        TypeMismatch = true;
+        break;
+      }
+    }
+  }
+
+  if (WrapperNeeded && !TypeMismatch) {
+    for (; PI != PE; ++PI)
+      Args.push_back(UndefValue::get(*PI));
+    if (F->isVarArg())
+      for (; AI != AE; ++AI)
+        Args.push_back(&*AI);
+
+    CallInst *Call = CallInst::Create(F, Args, "", BB);
+
+    Type *ExpectedRtnType = F->getFunctionType()->getReturnType();
+    Type *RtnType = Ty->getReturnType();
+    // Determine what value to return.
+    if (RtnType->isVoidTy()) {
+      ReturnInst::Create(M->getContext(), BB);
+    } else if (ExpectedRtnType->isVoidTy()) {
+      LLVM_DEBUG(dbgs() << "Creating dummy return: " << *RtnType << "\n");
+      ReturnInst::Create(M->getContext(), UndefValue::get(RtnType), BB);
+    } else if (RtnType == ExpectedRtnType) {
+      ReturnInst::Create(M->getContext(), Call, BB);
+    } else if (CastInst::isBitOrNoopPointerCastable(ExpectedRtnType, RtnType,
+                                                    DL)) {
+      Instruction *Cast =
+          CastInst::CreateBitOrPointerCast(Call, RtnType, "cast");
+      Cast->insertInto(BB, BB->end());
+      ReturnInst::Create(M->getContext(), Cast, BB);
+    } else if (RtnType->isStructTy() || ExpectedRtnType->isStructTy()) {
+      LLVM_DEBUG(dbgs() << "createWrapper: struct return type in bitcast: "
+                        << F->getName() << "\n");
+      WrapperNeeded = false;
+    } else {
+      LLVM_DEBUG(dbgs() << "createWrapper: return type mismatch calling: "
+                        << F->getName() << "\n");
+      LLVM_DEBUG(dbgs() << "Expected: " << *ExpectedRtnType
+                        << " Got: " << *RtnType << "\n");
+      TypeMismatch = true;
+    }
+  }
+
+  if (TypeMismatch) {
+    // Create a new wrapper that simply contains `unreachable`.
+    Wrapper->eraseFromParent();
+    Wrapper = Function::Create(Ty, Function::PrivateLinkage,
+                               F->getName() + "_bitcast_invalid", M);
+    BasicBlock *BB = BasicBlock::Create(M->getContext(), "body", Wrapper);
+    new UnreachableInst(M->getContext(), BB);
+    Wrapper->setName(F->getName() + "_bitcast_invalid");
+  } else if (!WrapperNeeded) {
+    LLVM_DEBUG(dbgs() << "createWrapper: no wrapper needed: " << F->getName()
+                      << "\n");
+    Wrapper->eraseFromParent();
+    return nullptr;
+  }
+  LLVM_DEBUG(dbgs() << "createWrapper: " << F->getName() << "\n");
+  return Wrapper;
+}
+
+// Test whether a main function with type FuncTy should be rewritten to have
+// type MainTy.
+static bool shouldFixMainFunction(FunctionType *FuncTy, FunctionType *MainTy) {
+  // Only fix the main function if it's the standard zero-arg form. That way,
+  // the standard cases will work as expected, and users will see signature
+  // mismatches from the linker for non-standard cases.
+  return FuncTy->getReturnType() == MainTy->getReturnType() &&
+         FuncTy->getNumParams() == 0 &&
+         !FuncTy->isVarArg();
+}
+
+bool FixFunctionBitcasts::runOnModule(Module &M) {
+  LLVM_DEBUG(dbgs() << "********** Fix Function Bitcasts **********\n");
+
+  Function *Main = nullptr;
+  CallInst *CallMain = nullptr;
+  SmallVector<std::pair<CallBase *, Function *>, 0> Uses;
+
+  // Collect all the places that need wrappers.
+  for (Function &F : M) {
+    // Skip to fix when the function is swiftcc because swiftcc allows
+    // bitcast type difference for swiftself and swifterror.
+    if (F.getCallingConv() == CallingConv::Swift)
+      continue;
+    findUses(&F, F, Uses);
+
+    // If we have a "main" function, and its type isn't
+    // "int main(int argc, char *argv[])", create an artificial call with it
+    // bitcasted to that type so that we generate a wrapper for it, so that
+    // the C runtime can call it.
+    if (F.getName() == "main") {
+      Main = &F;
+      LLVMContext &C = M.getContext();
+      Type *MainArgTys[] = {Type::getInt32Ty(C),
+                            PointerType::get(Type::getInt8PtrTy(C), 0)};
+      FunctionType *MainTy = FunctionType::get(Type::getInt32Ty(C), MainArgTys,
+                                               /*isVarArg=*/false);
+      if (shouldFixMainFunction(F.getFunctionType(), MainTy)) {
+        LLVM_DEBUG(dbgs() << "Found `main` function with incorrect type: "
+                          << *F.getFunctionType() << "\n");
+        Value *Args[] = {UndefValue::get(MainArgTys[0]),
+                         UndefValue::get(MainArgTys[1])};
+        Value *Casted =
+            ConstantExpr::getBitCast(Main, PointerType::get(MainTy, 0));
+        CallMain = CallInst::Create(MainTy, Casted, Args, "call_main");
+        Uses.push_back(std::make_pair(CallMain, &F));
+      }
+    }
+  }
+
+  DenseMap<std::pair<Function *, FunctionType *>, Function *> Wrappers;
+
+  for (auto &UseFunc : Uses) {
+    CallBase *CB = UseFunc.first;
+    Function *F = UseFunc.second;
+    FunctionType *Ty = CB->getFunctionType();
+
+    auto Pair = Wrappers.insert(std::make_pair(std::make_pair(F, Ty), nullptr));
+    if (Pair.second)
+      Pair.first->second = createWrapper(F, Ty);
+
+    Function *Wrapper = Pair.first->second;
+    if (!Wrapper)
+      continue;
+
+    CB->setCalledOperand(Wrapper);
+  }
+
+  // If we created a wrapper for main, rename the wrapper so that it's the
+  // one that gets called from startup.
+  if (CallMain) {
+    Main->setName("__original_main");
+    auto *MainWrapper =
+        cast<Function>(CallMain->getCalledOperand()->stripPointerCasts());
+    delete CallMain;
+    if (Main->isDeclaration()) {
+      // The wrapper is not needed in this case as we don't need to export
+      // it to anyone else.
+      MainWrapper->eraseFromParent();
+    } else {
+      // Otherwise give the wrapper the same linkage as the original main
+      // function, so that it can be called from the same places.
+      MainWrapper->setName("main");
+      MainWrapper->setLinkage(Main->getLinkage());
+      MainWrapper->setVisibility(Main->getVisibility());
+    }
+  }
+
+  return true;
+}