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65c98b9da4
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
63 lines
2.2 KiB
C++
63 lines
2.2 KiB
C++
//=== X86CallingConv.h - X86 Custom Calling Convention Routines -*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the custom routines for the X86 Calling Convention that
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// aren't done by tablegen.
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//
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//===----------------------------------------------------------------------===//
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#ifndef X86CALLINGCONV_H
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#define X86CALLINGCONV_H
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#include "llvm/CodeGen/CallingConvLower.h"
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#include "llvm/IR/CallingConv.h"
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namespace llvm {
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inline bool CC_X86_AnyReg_Error(unsigned &, MVT &, MVT &,
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CCValAssign::LocInfo &, ISD::ArgFlagsTy &,
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CCState &) {
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llvm_unreachable("The AnyReg calling convention is only supported by the " \
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"stackmap and patchpoint intrinsics.");
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// gracefully fallback to X86 C calling convention on Release builds.
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return false;
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}
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inline bool CC_X86_CDeclMethod_SRet(unsigned &ValNo, MVT &ValVT, MVT &LocVT,
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CCValAssign::LocInfo &LocInfo,
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ISD::ArgFlagsTy &ArgFlags, CCState &State) {
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// Swap the order of the first two parameters if the first parameter is sret.
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if (ArgFlags.isSRet()) {
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assert(ValNo == 0);
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assert(ValVT == MVT::i32);
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State.AllocateStack(8, 4);
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State.addLoc(CCValAssign::getCustomMem(ValNo, ValVT, 4, LocVT, LocInfo));
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// Indicate that we need to swap the order of the first and second
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// parameters by "allocating" register zero. There are no register
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// parameters with cdecl methods, so we can use this to communicate to the
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// next call.
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State.AllocateReg(1);
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return true;
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} else if (ValNo == 1 && State.isAllocated(1)) {
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assert(ValVT == MVT::i32 && "non-i32-sized this param unsupported");
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// Stack was already allocated while processing sret.
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State.addLoc(CCValAssign::getCustomMem(ValNo, ValVT, 0, LocVT, LocInfo));
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return true;
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}
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// All other args use the C calling convention.
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return false;
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}
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} // End llvm namespace
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#endif
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