llvm-6502/lib/Target/X86/X86CallingConv.h
Reid Kleckner 65c98b9da4 [ms-cxxabi] Add a new calling convention that swaps 'this' and 'sret'
MSVC always places the 'this' parameter for a method first.  The
implicit 'sret' pointer for methods always comes second.  We already
implement this for __thiscall by putting sret parameters on the stack,
but __cdecl methods require putting both parameters on the stack in
opposite order.

Using a special calling convention allows frontends to keep the sret
parameter first, which avoids breaking lots of assumptions in LLVM and
Clang.

Fixes PR15768 with the corresponding change in Clang.

Reviewers: ributzka, majnemer

Differential Revision: http://llvm-reviews.chandlerc.com/D2663

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200561 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-31 17:41:22 +00:00

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//=== X86CallingConv.h - X86 Custom Calling Convention Routines -*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the custom routines for the X86 Calling Convention that
// aren't done by tablegen.
//
//===----------------------------------------------------------------------===//
#ifndef X86CALLINGCONV_H
#define X86CALLINGCONV_H
#include "llvm/CodeGen/CallingConvLower.h"
#include "llvm/IR/CallingConv.h"
namespace llvm {
inline bool CC_X86_AnyReg_Error(unsigned &, MVT &, MVT &,
CCValAssign::LocInfo &, ISD::ArgFlagsTy &,
CCState &) {
llvm_unreachable("The AnyReg calling convention is only supported by the " \
"stackmap and patchpoint intrinsics.");
// gracefully fallback to X86 C calling convention on Release builds.
return false;
}
inline bool CC_X86_CDeclMethod_SRet(unsigned &ValNo, MVT &ValVT, MVT &LocVT,
CCValAssign::LocInfo &LocInfo,
ISD::ArgFlagsTy &ArgFlags, CCState &State) {
// Swap the order of the first two parameters if the first parameter is sret.
if (ArgFlags.isSRet()) {
assert(ValNo == 0);
assert(ValVT == MVT::i32);
State.AllocateStack(8, 4);
State.addLoc(CCValAssign::getCustomMem(ValNo, ValVT, 4, LocVT, LocInfo));
// Indicate that we need to swap the order of the first and second
// parameters by "allocating" register zero. There are no register
// parameters with cdecl methods, so we can use this to communicate to the
// next call.
State.AllocateReg(1);
return true;
} else if (ValNo == 1 && State.isAllocated(1)) {
assert(ValVT == MVT::i32 && "non-i32-sized this param unsupported");
// Stack was already allocated while processing sret.
State.addLoc(CCValAssign::getCustomMem(ValNo, ValVT, 0, LocVT, LocInfo));
return true;
}
// All other args use the C calling convention.
return false;
}
} // End llvm namespace
#endif