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MS inline asm: Use memory constraints for functions instead of registers

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This is consistent with how we parse them in a standalone .s file, and
inline assembly shouldn't differ.

This fixes errors about requiring more registers than available in
cases like this:
  void f();
  void __declspec(naked) g() {
    __asm pusha
    __asm call f
    __asm popa
    __asm ret
  }

There are no registers available to pass the address of 'f' into the asm
blob.  The asm should now directly call 'f'.

Tests will land in Clang shortly.

llvm-svn: 214550
This commit is contained in:
Reid Kleckner 2014-08-01 20:21:24 +00:00
parent a0f98c4e13
commit bfbea18b59
2 changed files with 31 additions and 10 deletions
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30
lib/Target/X86/AsmParser/X86AsmParser.cpp
View File

@ -731,6 +731,13 @@ private:
(X86::Mode64Bit | X86::Mode32Bit | X86::Mode16Bit)));
}
unsigned getPointerWidth() {
if (is16BitMode()) return 16;
if (is32BitMode()) return 32;
if (is64BitMode()) return 64;
llvm_unreachable("invalid mode");
}
bool isParsingIntelSyntax() {
return getParser().getAssemblerDialect();
}
@ -982,15 +989,20 @@ std::unique_ptr<X86Operand> X86AsmParser::CreateMemForInlineAsm(
unsigned SegReg, const MCExpr *Disp, unsigned BaseReg, unsigned IndexReg,
unsigned Scale, SMLoc Start, SMLoc End, unsigned Size, StringRef Identifier,
InlineAsmIdentifierInfo &Info) {
// If this is not a VarDecl then assume it is a FuncDecl or some other label
// reference. We need an 'r' constraint here, so we need to create register
// operand to ensure proper matching. Just pick a GPR based on the size of
// a pointer.
if (isa<MCSymbolRefExpr>(Disp) && !Info.IsVarDecl) {
unsigned RegNo =
is64BitMode() ? X86::RBX : (is32BitMode() ? X86::EBX : X86::BX);
return X86Operand::CreateReg(RegNo, Start, End, /*AddressOf=*/true,
SMLoc(), Identifier, Info.OpDecl);
// If we found a decl other than a VarDecl, then assume it is a FuncDecl or
// some other label reference.
if (isa<MCSymbolRefExpr>(Disp) && Info.OpDecl && !Info.IsVarDecl) {
// Insert an explicit size if the user didn't have one.
if (!Size) {
Size = getPointerWidth();
InstInfo->AsmRewrites->push_back(AsmRewrite(AOK_SizeDirective, Start,
/*Len=*/0, Size));
}
// Create an absolute memory reference in order to match against
// instructions taking a PC relative operand.
return X86Operand::CreateMem(Disp, Start, End, Size, Identifier,
Info.OpDecl);
}
// We either have a direct symbol reference, or an offset from a symbol. The

11
test/CodeGen/X86/ms-inline-asm.ll
View File

@ -110,7 +110,7 @@ define i32 @t31() {
entry:
%val = alloca i32, align 64
store i32 -1, i32* %val, align 64
call void asm sideeffect inteldialect "mov dword ptr $0, esp", "=*m,~{dirflag},~{fpsr},~{flags}"(i32* %val) #1
call void asm sideeffect inteldialect "mov dword ptr $0, esp", "=*m,~{dirflag},~{fpsr},~{flags}"(i32* %val)
%sp = load i32* %val, align 64
ret i32 %sp
; CHECK-LABEL: t31:
@ -125,3 +125,12 @@ entry:
; CHECK: movl (%esp), %eax
; CHECK: ret
}
declare void @other_func()
define void @naked() #0 {
call void asm sideeffect inteldialect "call dword ptr $0", "*m,~{eax},~{ebx},~{ecx},~{edx},~{edi},~{esi},~{esp},~{ebp},~{dirflag},~{fpsr},~{flags}"(void()* @other_func)
unreachable
}
attributes #0 = { naked }