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

1 files changed, 6 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 149cec26411..b5dd2d4cca8 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -1396,7 +1396,12 @@ static std::string scalarConstantToHexString(const Constant *C) {
 MCSection *TargetLoweringObjectFileCOFF::getSectionForConstant(
     const DataLayout &DL, SectionKind Kind, const Constant *C,
     unsigned &Align) const {
-  if (Kind.isMergeableConst() && C) {
+  if (Kind.isMergeableConst() && C &&
+      getContext().getAsmInfo()->hasCOFFComdatConstants()) {
+    // This creates comdat sections with the given symbol name, but unless
+    // AsmPrinter::GetCPISymbol actually makes the symbol global, the symbol
+    // will be created with a null storage class, which makes GNU binutils
+    // error out.
     const unsigned Characteristics = COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
                                      COFF::IMAGE_SCN_MEM_READ |
                                      COFF::IMAGE_SCN_LNK_COMDAT;