llvm-mirror/lib/IR/User.cpp
Yaron Keren 3d4f34c936 In Release modes, Visual Studio complains that the Operator destructor in User.cpp
never returns, which is true by design. 

Initially assumed that the reason is llvm_unreachable being dependent on NDEBUG.

However, even if llvm_unreachable is replaced by __assume(false), VC still warns in
Release modes but not in Debug modes...

The real reason turned out to be optimization flags.
With /Od in Debug modes the warning is not issued whereas with /O1 it is.

I could not find any documentation to this effect, but it is reproducable:

Try compiling http://msdn.microsoft.com/en-us/library/khwfyc5d(v=vs.90).aspx
with /O1 and then with /Od.

llvm-svn: 204659
2014-03-24 19:48:13 +00:00

111 lines
4.2 KiB
C++

//===-- User.cpp - Implement the User class -------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/IR/User.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/Operator.h"
namespace llvm {
//===----------------------------------------------------------------------===//
// User Class
//===----------------------------------------------------------------------===//
void User::anchor() {}
// replaceUsesOfWith - Replaces all references to the "From" definition with
// references to the "To" definition.
//
void User::replaceUsesOfWith(Value *From, Value *To) {
if (From == To) return; // Duh what?
assert((!isa<Constant>(this) || isa<GlobalValue>(this)) &&
"Cannot call User::replaceUsesOfWith on a constant!");
for (unsigned i = 0, E = getNumOperands(); i != E; ++i)
if (getOperand(i) == From) { // Is This operand is pointing to oldval?
// The side effects of this setOperand call include linking to
// "To", adding "this" to the uses list of To, and
// most importantly, removing "this" from the use list of "From".
setOperand(i, To); // Fix it now...
}
}
//===----------------------------------------------------------------------===//
// User allocHungoffUses Implementation
//===----------------------------------------------------------------------===//
Use *User::allocHungoffUses(unsigned N) const {
// Allocate the array of Uses, followed by a pointer (with bottom bit set) to
// the User.
size_t size = N * sizeof(Use) + sizeof(Use::UserRef);
Use *Begin = static_cast<Use*>(::operator new(size));
Use *End = Begin + N;
(void) new(End) Use::UserRef(const_cast<User*>(this), 1);
return Use::initTags(Begin, End);
}
//===----------------------------------------------------------------------===//
// User operator new Implementations
//===----------------------------------------------------------------------===//
void *User::operator new(size_t s, unsigned Us) {
void *Storage = ::operator new(s + sizeof(Use) * Us);
Use *Start = static_cast<Use*>(Storage);
Use *End = Start + Us;
User *Obj = reinterpret_cast<User*>(End);
Obj->OperandList = Start;
Obj->NumOperands = Us;
Use::initTags(Start, End);
return Obj;
}
//===----------------------------------------------------------------------===//
// User operator delete Implementation
//===----------------------------------------------------------------------===//
void User::operator delete(void *Usr) {
User *Start = static_cast<User*>(Usr);
Use *Storage = static_cast<Use*>(Usr) - Start->NumOperands;
// If there were hung-off uses, they will have been freed already and
// NumOperands reset to 0, so here we just free the User itself.
::operator delete(Storage);
}
//===----------------------------------------------------------------------===//
// Operator Class
//===----------------------------------------------------------------------===//
#if defined(_MSC_VER)
// In Release modes, Visual Studio complains that the Operator destructor
// never returns, which is true by design.
// This does *not* depend on llvm_unreachable being dependent on NDEBUG:
// even if llvm_unreachable is replaced by __assume(false), VC still warns in
// Release modes but not in Debug modes. The real reason is optimization flags.
// With /Od in Debug modes the warning is not issued whereas with /O1 it is.
// I could not find any documentation to this effect, it is reproducable:
// Try compiling http://msdn.microsoft.com/en-us/library/khwfyc5d(v=vs.90).aspx
// with /O1 and then with /Od.
// Anyhow, solution is same as lib/Support/Process.cpp:~self_process().
#pragma warning(push)
#pragma warning(disable:4722)
#endif
Operator::~Operator() {
llvm_unreachable("should never destroy an Operator");
}
#if defined(_MSC_VER)
#pragma warning(pop)
#endif
} // End llvm namespace