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llvm-mirror/lib/MC/MCAsmInfoCOFF.cpp
Martin Storsjo a4fa0f747f Revert "[COFF] Use comdat shared constants for MinGW as well"
This reverts commit r337951.

While that kind of shared constant generally works fine in a MinGW
setting, it broke some cases of inline assembly that worked before:

$ cat const-asm.c
int MULH(int a, int b) {
    int rt, dummy;
    __asm__ (
        "imull %3"
        :"=d"(rt), "=a"(dummy)
        :"a"(a), "rm"(b)
    );
    return rt;
}
int func(int a) {
    return MULH(a, 1);
}
$ clang -target x86_64-win32-gnu -c const-asm.c -O2
const-asm.c:4:9: error: invalid variant '00000001'
        "imull %3"
        ^
<inline asm>:1:15: note: instantiated into assembly here
        imull __real@00000001(%rip)
                     ^

A similar error is produced for i686 as well. The same test with a
target of x86_64-win32-msvc or i686-win32-msvc works fine.

llvm-svn: 338018
2018-07-26 10:48:20 +00:00

70 lines
2.2 KiB
C++

//===- MCAsmInfoCOFF.cpp - COFF asm properties ----------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines target asm properties related what form asm statements
// should take in general on COFF-based targets
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCAsmInfoCOFF.h"
#include "llvm/MC/MCDirectives.h"
using namespace llvm;
void MCAsmInfoCOFF::anchor() {}
MCAsmInfoCOFF::MCAsmInfoCOFF() {
// MingW 4.5 and later support .comm with log2 alignment, but .lcomm uses byte
// alignment.
COMMDirectiveAlignmentIsInBytes = false;
LCOMMDirectiveAlignmentType = LCOMM::ByteAlignment;
HasDotTypeDotSizeDirective = false;
HasSingleParameterDotFile = false;
WeakRefDirective = "\t.weak\t";
HasLinkOnceDirective = true;
// Doesn't support visibility:
HiddenVisibilityAttr = HiddenDeclarationVisibilityAttr = MCSA_Invalid;
ProtectedVisibilityAttr = MCSA_Invalid;
// Set up DWARF directives
SupportsDebugInformation = true;
NeedsDwarfSectionOffsetDirective = true;
UseIntegratedAssembler = true;
// At least MSVC inline-asm does AShr.
UseLogicalShr = false;
// If this is a COFF target, assume that it supports associative comdats. It's
// part of the spec.
HasCOFFAssociativeComdats = true;
// We can generate constants in comdat sections that can be shared,
// but in order not to create null typed symbols, we actually need to
// make them global symbols as well.
HasCOFFComdatConstants = true;
}
void MCAsmInfoMicrosoft::anchor() {}
MCAsmInfoMicrosoft::MCAsmInfoMicrosoft() = default;
void MCAsmInfoGNUCOFF::anchor() {}
MCAsmInfoGNUCOFF::MCAsmInfoGNUCOFF() {
// If this is a GNU environment (mingw or cygwin), don't use associative
// comdats for jump tables, unwind information, and other data associated with
// a function.
HasCOFFAssociativeComdats = false;
// We don't create constants in comdat sections for MinGW.
HasCOFFComdatConstants = false;
}