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[X86] Avoid mangling frameescape labels 

x86 Windows uses the '_' prefix for all global symbols, and this was
mistakenly being applied to frameescape labels, which are not externally
visible global symbols. They use the private global prefix 'L'.

The *right* way to fix this is probably to stop masquerading this label
as an ExternalSymbol and create a new SDNode type. These labels are not
"external", and we know they will be resolved by assembly time. Having a
custom SDNode type would allow us to do better X86 address mode
matching, so it's probably worth doing eventually.

llvm-svn: 236123
This commit is contained in:
Reid Kleckner 2015-04-29 16:46:01 +00:00
parent d7d088f815
commit c695471365
4 changed files with 15 additions and 5 deletions
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6
llvm/lib/Target/X86/MCTargetDesc/X86BaseInfo.h
View File

@ -213,7 +213,11 @@ namespace X86II {
/// the offset from beginning of section.
///
/// This is the TLS offset for the COFF/Windows TLS mechanism.
MO_SECREL
MO_SECREL,
/// MO_NOPREFIX - On a symbol operand this indicates that the symbol should
/// not be mangled with a prefix.
MO_NOPREFIX,
};
enum : uint64_t {

2
llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
View File

@ -1009,7 +1009,9 @@ bool X86DAGToDAGISel::MatchAddressRecursively(SDValue N, X86ISelAddressMode &AM,
if (!AM.hasSymbolicDisplacement())
if (const auto *ESNode = dyn_cast<ExternalSymbolSDNode>(N.getOperand(0)))
if (ESNode->getOpcode() == ISD::TargetExternalSymbol) {
// Use the symbol and don't prefix it.
AM.ES = ESNode->getSymbol();
AM.SymbolFlags = X86II::MO_NOPREFIX;
return false;
}
break;

6
llvm/lib/Target/X86/X86MCInstLower.cpp
View File

@ -154,7 +154,10 @@ GetSymbolFromOperand(const MachineOperand &MO) const {
const GlobalValue *GV = MO.getGlobal();
AsmPrinter.getNameWithPrefix(Name, GV);
} else if (MO.isSymbol()) {
getMang()->getNameWithPrefix(Name, MO.getSymbolName());
if (MO.getTargetFlags() == X86II::MO_NOPREFIX)
Name += MO.getSymbolName();
else
getMang()->getNameWithPrefix(Name, MO.getSymbolName());
} else if (MO.isMBB()) {
Name += MO.getMBB()->getSymbol()->getName();
}
@ -231,6 +234,7 @@ MCOperand X86MCInstLower::LowerSymbolOperand(const MachineOperand &MO,
case X86II::MO_DARWIN_NONLAZY:
case X86II::MO_DLLIMPORT:
case X86II::MO_DARWIN_STUB:
case X86II::MO_NOPREFIX:
break;
case X86II::MO_TLVP: RefKind = MCSymbolRefExpr::VK_TLVP; break;

6
llvm/test/CodeGen/X86/frameescape.ll
View File

@ -37,15 +37,15 @@ define void @print_framealloc_from_fp(i8* %fp) {
; X86: pushl %esi
; X86: subl $8, %esp
; X86: movl 16(%esp), %esi
; X86: movl _Lalloc_func$frame_escape_0(%esi), %eax
; X86: movl Lalloc_func$frame_escape_0(%esi), %eax
; X86: movl %eax, 4(%esp)
; X86: movl $_str, (%esp)
; X86: calll _printf
; X86: movl _Lalloc_func$frame_escape_1(%esi), %eax
; X86: movl Lalloc_func$frame_escape_1(%esi), %eax
; X86: movl %eax, 4(%esp)
; X86: movl $_str, (%esp)
; X86: calll _printf
; X86: movl $42, _Lalloc_func$frame_escape_1(%esi)
; X86: movl $42, Lalloc_func$frame_escape_1(%esi)
; X86: addl $8, %esp
; X86: popl %esi
; X86: retl