PNaCl: Extend ExpandMulWithOverflow pass to handle uadd.with.overflow too

lib/Transforms/NaCl/ExpandMulWithOverflow.cpp

Index: lib/Transforms/NaCl/ExpandMulWithOverflow.cpp
diff --git a/lib/Transforms/NaCl/ExpandMulWithOverflow.cpp b/lib/Transforms/NaCl/ExpandMulWithOverflow.cpp
deleted file mode 100644
index 171dda1f09290fd06a04c45caf73503b73b2c402..0000000000000000000000000000000000000000
--- a/lib/Transforms/NaCl/ExpandMulWithOverflow.cpp
+++ /dev/null
@@ -1,141 +0,0 @@
-//===- ExpandMulWithOverflow.cpp - Expand out usage of umul.with.overflow--===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// The llvm.*.with.overflow.*() intrinsics are awkward for PNaCl
-// support because they return structs, and we want to omit struct
-// types from IR in PNaCl's stable ABI.
-//
-// However, llvm.umul.with.overflow.*() is used by Clang to implement
-// an overflow check for C++'s new[] operator.  This pass expands out
-// these uses so that PNaCl does not have to support
-// umul.with.overflow as part of PNaCl's stable ABI.
-//
-// This pass only handles multiplication by a constant, which is the
-// only case of umul.with.overflow that is currently generated by
-// Clang (unless '-ftrapv' is passed to Clang).
-//
-// X * Const overflows iff X > UINT_MAX / Const, where UINT_MAX is the
-// maximum value for the integer type being multiplied.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/IR/Function.h"
-#include "llvm/IR/Instructions.h"
-#include "llvm/IR/Intrinsics.h"
-#include "llvm/IR/Module.h"
-#include "llvm/Pass.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Transforms/NaCl.h"
-
-using namespace llvm;
-
-namespace {
-  // This is a ModulePass so that the pass can easily iterate over all
-  // uses of the intrinsics.
-  class ExpandMulWithOverflow : public ModulePass {
-  public:
-    static char ID; // Pass identification, replacement for typeid
-    ExpandMulWithOverflow() : ModulePass(ID) {
-      initializeExpandMulWithOverflowPass(*PassRegistry::getPassRegistry());
-    }
-
-    virtual bool runOnModule(Module &M);
-  };
-}
-
-char ExpandMulWithOverflow::ID = 0;
-INITIALIZE_PASS(ExpandMulWithOverflow, "expand-mul-with-overflow",
-                "Expand out uses of llvm.umul.with.overflow intrinsics",
-                false, false)
-
-static uint64_t UintTypeMax(unsigned Bits) {
-  // Avoid doing 1 << 64 because that is undefined on a uint64_t.
-  if (Bits == 64)
-    return ~(uint64_t) 0;
-  return (((uint64_t) 1) << Bits) - 1;
-}
-
-static bool ExpandForIntSize(Module *M, unsigned Bits) {
-  IntegerType *IntTy = IntegerType::get(M->getContext(), Bits);
-  SmallVector<Type *, 1> Types;
-  Types.push_back(IntTy);
-  std::string Name = Intrinsic::getName(Intrinsic::umul_with_overflow, Types);
-  Function *Intrinsic = M->getFunction(Name);
-  if (!Intrinsic)
-    return false;
-  for (Value::use_iterator CallIter = Intrinsic->use_begin(),
-         E = Intrinsic->use_end(); CallIter != E; ) {
-    CallInst *Call = dyn_cast<CallInst>(*CallIter++);
-    if (!Call) {
-      report_fatal_error("ExpandMulWithOverflow: Taking the address of a "
-                         "umul.with.overflow intrinsic is not allowed");
-    }
-    Value *VariableArg;
-    ConstantInt *ConstantArg;
-    if (ConstantInt *C = dyn_cast<ConstantInt>(Call->getArgOperand(0))) {
-      VariableArg = Call->getArgOperand(1);
-      ConstantArg = C;
-    } else if (ConstantInt *C = dyn_cast<ConstantInt>(Call->getArgOperand(1))) {
-      VariableArg = Call->getArgOperand(0);
-      ConstantArg = C;
-    } else {
-      errs() << "Use: " << *Call << "\n";
-      report_fatal_error("ExpandMulWithOverflow: At least one argument of "
-                         "umul.with.overflow must be a constant");
-    }
-
-    Value *Mul = BinaryOperator::Create(
-        Instruction::Mul, VariableArg, ConstantArg,
-        Call->getName() + ".mul", Call);
-
-    uint64_t ArgMax = UintTypeMax(Bits) / ConstantArg->getZExtValue();
-    Value *Overflow = new ICmpInst(
-        Call, CmpInst::ICMP_UGT, VariableArg, ConstantInt::get(IntTy, ArgMax),
-        Call->getName() + ".overflow");
-
-    for (Value::use_iterator FieldIter = Call->use_begin(),
-           E = Call->use_end(); FieldIter != E; ) {
-      User *U = *FieldIter++;
-      ExtractValueInst *Field = dyn_cast<ExtractValueInst>(U);
-      if (!Field) {
-        errs() << "Use: " << *U << "\n";
-        report_fatal_error(
-            "ExpandMulWithOverflow: Use is not an extractvalue");
-      }
-      if (Field->getNumIndices() != 1) {
-        report_fatal_error("ExpandMulWithOverflow: Unexpected indices");
-      }
-      unsigned Index = Field->getIndices()[0];
-      if (Index == 0) {
-        Field->replaceAllUsesWith(Mul);
-      } else if (Index == 1) {
-        Field->replaceAllUsesWith(Overflow);
-      } else {
-        report_fatal_error("ExpandMulWithOverflow: Unexpected index");
-      }
-      Field->eraseFromParent();
-    }
-    Call->eraseFromParent();
-  }
-  Intrinsic->eraseFromParent();
-  return true;
-}
-
-bool ExpandMulWithOverflow::runOnModule(Module &M) {
-  bool Modified = false;
-  Modified |= ExpandForIntSize(&M, 64);
-  Modified |= ExpandForIntSize(&M, 32);
-  Modified |= ExpandForIntSize(&M, 16);
-  Modified |= ExpandForIntSize(&M, 8);
-  return Modified;
-}
-
-ModulePass *llvm::createExpandMulWithOverflowPass() {
-  return new ExpandMulWithOverflow();
-}