[clang] Make -masm=intel affect inline asm style

[thakis]

Summary

With this,

void f() {  __asm__("mov eax, ebx"); }

now compiles with clang with -masm=intel.

This matches gcc.

The flag is not accepted in clang-cl mode. It has no effect on
MSVC-style __asm {} blocks, which are unconditionally in intel
mode both before and after this change.

One difference to gcc is that in clang, inline asm strings are
"local" while they're "global" in gcc. Building the following with
-masm=intel works with clang, but not with gcc where the ".att_syntax"
from the 2nd asm() is in effect until file end (or until a
".intel_syntax" somewhere later in the file):

__asm__("mov eax, ebx");
__asm__(".att_syntax\nmovl %ebx, %eax");
__asm__("mov eax, ebx");

This also updates clang's intrinsic headers to work both in
-masm=att (the default) and -masm=intel modes.
The official solution for this according to "Multiple assembler dialects in asm
templates" in gcc docs->Extensions->Inline Assembly->Extended Asm
is to write every inline asm snippet twice:

bt{l %[Offset],%[Base] | %[Base],%[Offset]}

This works in LLVM after D113932 and D113894, so use that.
(Just putting .att_syntax at the start of the snippet works in some but not
all cases: When LLVM interpolates in parameters like %0, it uses at&t or
intel syntax according to the inline asm snippet's flavor, so the .att_syntax
within the snippet happens to late: The interpolated-in parameter is already
in intel style, and then won't parse in the switched .att_syntax)
It might be nice to invent a #pragma clang asm_dialect push "att" /
#pragma clang asm_dialect pop to be able to force asm style per snippet,
so that the inline asm string doesn't contain the same code in two variants,
but let's leave that for a follow-up.

Fixes PR21401 and PR20241.

[rnk]

This seems reasonable, but I worry about headers that contain AT&T style inline asm blobs, such as clang's own intrinsic headers. As you say, the directive is local. I would hate to end up in a place where we have to prefix every asm blob in clang/lib/Headers/*mmintrin.h with ".att_syntax on;".

Actually, git grep __asm__ ../clang/lib/Headers shows that there are not very many blobs. Maybe we should just prefix them.

[thakis]

Thanks for pointing out built-in headers, that's a great point. I started adding .att_syntax lines where needed, but the I realized that that doens't work: it's too late for things taking memory, since %0 replacement is done with asm writer setting before getting to reading the snippet. So %0 is replaced with (say) [eax] before things get to the asm parser, and then .att_syntax switches it to att syntax, and then it says "can't do [eax] in att syntax".

The official solution for this according to "Multiple assembler dialects in asm templates" in gcc docs->Extensions->Inline Assembly->Extended Asm is to write every inline asm snippet twice: bt{l %[Offset],%[Base] | %[Base],%[Offset]}. clang doesn't yet support {|}. So I think I have to update this patch to make clang support {|} and use that in the intrinsic headers where needed.

[rnk]

One alternative would be to control this setting with a pragma stack, like we do for warnings, struct packing, etc. Something like:

// foo.h
#pragma clang asm_dialect push "att"
static inline ... foo { asm("..."); }
#pragma clang asm_dialect pop

The pragma really would just control the dialect on the inline asm blob, not the output assembly.

It seems more user friendly since they don't have to write two variants of their inline asm, but it is new and not compatible with any existing code.

[thakis]

• rebase on top of recent (partially still pending) llvm patches
• use {...|...} in intrinsic headers

[thakis]

Fairly big update. I'd like to punt on the pragma for now since this became a lot more involved than expected already (see dependent patches; several of them have already landed).

[thakis]

minor test expectations update

[rnk]

In D113707#3132812, @thakis wrote:

Fairly big update. I'd like to punt on the pragma for now since this became a lot more involved than expected already (see dependent patches; several of them have already landed).

No problem.

This seems very reasonable.

[thakis]

(Here are a few revisions I read through while researching this patch:

da081a8e1f295ffdd670f87dba19f470a9a5acaa
and fc416faaa07c5
(and 4f2791617e2fa)
and aa23fa9f435d2

1778831a3d1d2 split the "ms" inline asm out

isSimple added in 19fe116fc0b35, meaningfully used in b737b6247f051)

[hans]

lgtm

clang/lib/Headers/x86gprintrin.h

29

the 'l' suffix is probably not even needed for any of these movs?

clang/test/CodeGen/inline-asm-intel.c

3

Could the interesting flags (-triple x86_64-unknown-unknown -mllvm -x86-asm-syntax=att -inline-asm=intel) be put right at the beginning or end of the run lines? They're pretty long, so easy to get lost in the woods otherwise.

(I think the triple slash prefix is uncommon in clang tests.)

11

Maybe give these a comment too?

[thakis]

Derp, I landed this without replying to the comments. I'll do a follow-up commit for them right now.

[thakis]

https://reviews.llvm.org/rGb1ad813b474a

[thakis]

This contained a bug in that I didn't change CompilerInvocation::GenerateCodeGenArgs() to serialize the new flag correctly, so in build configs that do roundtripping the test failed.

I fixed the marshalling in https://reviews.llvm.org/rG36873fb768dbedeb3e9167117d3bb63b3720d214 (and https://reviews.llvm.org/rG3623163ae83799933bbeabe2cb3060537250c4b3), and I made https://reviews.llvm.org/D114120 to make sure more build configs do roundtripping (with that, I would've seen this locally instead of only on the bots).

clang/include/clang/Basic/CodeGenOptions.h

public:
 
   enum EmbedBitcodeKind {
     Embed_Off,      // No embedded bitcode.
     Embed_All,      // Embed both bitcode and commandline in the output.
     Embed_Bitcode,  // Embed just the bitcode in the output.
     Embed_Marker    // Embed a marker as a placeholder for bitcode.
   };
 
+  enum InlineAsmDialectKind {
+    IAD_ATT,
+    IAD_Intel,
+  };
+
   // This field stores one of the allowed values for the option
   // -fbasic-block-sections=.  The allowed values with this option are:
   // {"labels", "all", "list=<file>", "none"}.
   //
   // "labels":      Only generate basic block symbols (labels) for all basic
   //                blocks, do not generate unique sections for basic blocks.
   //                Use the machine basic block id in the symbol name to
   //                associate profile info from virtual address to machine

clang/include/clang/Basic/CodeGenOptions.def

 CODEGENOPT(EmitVersionIdentMetadata , 1, 1) ///< Emit compiler version metadata.
 CODEGENOPT(EmitGcovArcs      , 1, 0) ///< Emit coverage data files, aka. GCDA.
 CODEGENOPT(EmitGcovNotes     , 1, 0) ///< Emit coverage "notes" files, aka GCNO.
 CODEGENOPT(EmitOpenCLArgMetadata , 1, 0) ///< Emit OpenCL kernel arg metadata.
 CODEGENOPT(EmulatedTLS       , 1, 0) ///< Set by default or -f[no-]emulated-tls.
 CODEGENOPT(ExplicitEmulatedTLS , 1, 0) ///< Set if -f[no-]emulated-tls is used.
 /// Embed Bitcode mode (off/all/bitcode/marker).
 ENUM_CODEGENOPT(EmbedBitcode, EmbedBitcodeKind, 2, Embed_Off)
+/// Inline asm dialect, -masm=(att|intel)
+ENUM_CODEGENOPT(InlineAsmDialect, InlineAsmDialectKind, 1, IAD_ATT)
 CODEGENOPT(ForbidGuardVariables , 1, 0) ///< Issue errors if C++ guard variables
                                         ///< are required.
 CODEGENOPT(FunctionSections  , 1, 0) ///< Set when -ffunction-sections is enabled.
 CODEGENOPT(InstrumentFunctions , 1, 0) ///< Set when -finstrument-functions is
                                        ///< enabled.
 CODEGENOPT(InstrumentFunctionsAfterInlining , 1, 0) ///< Set when
                           ///< -finstrument-functions-after-inlining is enabled.
 CODEGENOPT(InstrumentFunctionEntryBare , 1, 0) ///< Set when

clang/include/clang/Driver/Options.td

 def mappletvos_version_min_EQ : Joined<["-"], "mappletvos-version-min=">, Alias<mtvos_version_min_EQ>;
 def mtvos_simulator_version_min_EQ : Joined<["-"], "mtvos-simulator-version-min=">;
 def mappletvsimulator_version_min_EQ : Joined<["-"], "mappletvsimulator-version-min=">, Alias<mtvos_simulator_version_min_EQ>;
 def mwatchos_version_min_EQ : Joined<["-"], "mwatchos-version-min=">, Group<m_Group>;
 def mwatchos_simulator_version_min_EQ : Joined<["-"], "mwatchos-simulator-version-min=">;
 def mwatchsimulator_version_min_EQ : Joined<["-"], "mwatchsimulator-version-min=">, Alias<mwatchos_simulator_version_min_EQ>;
 def march_EQ : Joined<["-"], "march=">, Group<m_Group>, Flags<[CoreOption]>;
 def masm_EQ : Joined<["-"], "masm=">, Group<m_Group>, Flags<[NoXarchOption]>;
+def inline_asm_EQ : Joined<["-"], "inline-asm=">, Group<m_Group>, Flags<[CC1Option]>;
 def mcmodel_EQ : Joined<["-"], "mcmodel=">, Group<m_Group>, Flags<[CC1Option]>,
   MarshallingInfoString<TargetOpts<"CodeModel">, [{"default"}]>;
 def mtls_size_EQ : Joined<["-"], "mtls-size=">, Group<m_Group>, Flags<[NoXarchOption, CC1Option]>,
   HelpText<"Specify bit size of immediate TLS offsets (AArch64 ELF only): "
            "12 (for 4KB) | 24 (for 16MB, default) | 32 (for 4GB) | 48 (for 256TB, needs -mcmodel=large)">,
   MarshallingInfoInt<CodeGenOpts<"TLSSize">>;
 def mimplicit_it_EQ : Joined<["-"], "mimplicit-it=">, Group<m_Group>;
 def mdefault_build_attributes : Joined<["-"], "mdefault-build-attributes">, Group<m_Group>;

clang/lib/CodeGen/CGStmt.cpp

else if (ResultRegTypes.size() == 1)
     ResultType = ResultRegTypes[0];
   else
     ResultType = llvm::StructType::get(getLLVMContext(), ResultRegTypes);
 
   llvm::FunctionType *FTy =
     llvm::FunctionType::get(ResultType, ArgTypes, false);
 
   bool HasSideEffect = S.isVolatile() || S.getNumOutputs() == 0;
+
+  llvm::InlineAsm::AsmDialect GnuAsmDialect =
+      CGM.getCodeGenOpts().getInlineAsmDialect() == CodeGenOptions::IAD_ATT
+          ? llvm::InlineAsm::AD_ATT
+          : llvm::InlineAsm::AD_Intel;
   llvm::InlineAsm::AsmDialect AsmDialect = isa<MSAsmStmt>(&S) ?
-    llvm::InlineAsm::AD_Intel : llvm::InlineAsm::AD_ATT;
+    llvm::InlineAsm::AD_Intel : GnuAsmDialect;
+
   llvm::InlineAsm *IA = llvm::InlineAsm::get(
       FTy, AsmString, Constraints, HasSideEffect,
       /* IsAlignStack */ false, AsmDialect, HasUnwindClobber);
   std::vector<llvm::Value*> RegResults;
   if (IsGCCAsmGoto) {
     llvm::CallBrInst *Result =
         Builder.CreateCallBr(IA, Fallthrough, Transfer, Args);
     EmitBlock(Fallthrough);

clang/lib/Driver/ToolChains/Clang.cpp

void Clang::AddX86TargetArgs(const ArgList &Args,
   if (NoImplicitFloat)
     CmdArgs.push_back("-no-implicit-float");
 
   if (Arg *A = Args.getLastArg(options::OPT_masm_EQ)) {
     StringRef Value = A->getValue();
     if (Value == "intel" || Value == "att") {
       CmdArgs.push_back("-mllvm");
       CmdArgs.push_back(Args.MakeArgString("-x86-asm-syntax=" + Value));
+      CmdArgs.push_back(Args.MakeArgString("-inline-asm=" + Value));
     } else {
       D.Diag(diag::err_drv_unsupported_option_argument)
           << A->getOption().getName() << Value;
     }
   } else if (D.IsCLMode()) {
     CmdArgs.push_back("-mllvm");
     CmdArgs.push_back("-x86-asm-syntax=intel");
   }

clang/lib/Frontend/CompilerInvocation.cpp

if (Opts.OptimizationLevel > 0) {
         Opts.setInlining(CodeGenOptions::NormalInlining);
       else if (InlineOpt.matches(options::OPT_finline_hint_functions))
         Opts.setInlining(CodeGenOptions::OnlyHintInlining);
       else
         Opts.setInlining(CodeGenOptions::OnlyAlwaysInlining);
     }
   }
 
+  if (Arg *A = Args.getLastArg(options::OPT_inline_asm_EQ)) {
+    StringRef Value = A->getValue();
+    if (Value == "att") {
+      Opts.InlineAsmDialect = CodeGenOptions::IAD_ATT;
+    } else if (Value == "intel") {
+      Opts.InlineAsmDialect = CodeGenOptions::IAD_Intel;
+    } else {
+      Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args)
+                                                << A->getValue();
+    }
+  }
+
   // PIC defaults to -fno-direct-access-external-data while non-PIC defaults to
   // -fdirect-access-external-data.
   Opts.DirectAccessExternalData =
       Args.hasArg(OPT_fdirect_access_external_data) ||
       (!Args.hasArg(OPT_fno_direct_access_external_data) &&
        LangOpts->PICLevel == 0);
 
   if (Arg *A = Args.getLastArg(OPT_debug_info_kind_EQ)) {

clang/lib/Headers/immintrin.h

 extern "C" {
 #endif
 /*----------------------------------------------------------------------------*\
 |* Interlocked Exchange HLE
 \*----------------------------------------------------------------------------*/
 #if defined(__i386__) || defined(__x86_64__)
 static __inline__ long __DEFAULT_FN_ATTRS
 _InterlockedExchange_HLEAcquire(long volatile *_Target, long _Value) {
-  __asm__ __volatile__(".byte 0xf2 ; lock ; xchg %0, %1"
+  __asm__ __volatile__(".byte 0xf2 ; lock ; xchg {%0, %1|%1, %0}"
                        : "+r" (_Value), "+m" (*_Target) :: "memory");
   return _Value;
 }
 static __inline__ long __DEFAULT_FN_ATTRS
 _InterlockedExchange_HLERelease(long volatile *_Target, long _Value) {
-  __asm__ __volatile__(".byte 0xf3 ; lock ; xchg %0, %1"
+  __asm__ __volatile__(".byte 0xf3 ; lock ; xchg {%0, %1|%1, %0}"
                        : "+r" (_Value), "+m" (*_Target) :: "memory");
   return _Value;
 }
 #endif
 #if defined(__x86_64__)
 static __inline__ __int64 __DEFAULT_FN_ATTRS
 _InterlockedExchange64_HLEAcquire(__int64 volatile *_Target, __int64 _Value) {
-  __asm__ __volatile__(".byte 0xf2 ; lock ; xchg %0, %1"
+  __asm__ __volatile__(".byte 0xf2 ; lock ; xchg {%0, %1|%1, %0}"
                        : "+r" (_Value), "+m" (*_Target) :: "memory");
   return _Value;
 }
 static __inline__ __int64 __DEFAULT_FN_ATTRS
 _InterlockedExchange64_HLERelease(__int64 volatile *_Target, __int64 _Value) {
-  __asm__ __volatile__(".byte 0xf3 ; lock ; xchg %0, %1"
+  __asm__ __volatile__(".byte 0xf3 ; lock ; xchg {%0, %1|%1, %0}"
                        : "+r" (_Value), "+m" (*_Target) :: "memory");
   return _Value;
 }
 #endif
 /*----------------------------------------------------------------------------*\
 |* Interlocked Compare Exchange HLE
 \*----------------------------------------------------------------------------*/
 #if defined(__i386__) || defined(__x86_64__)
 static __inline__ long __DEFAULT_FN_ATTRS
 _InterlockedCompareExchange_HLEAcquire(long volatile *_Destination,
                               long _Exchange, long _Comparand) {
-  __asm__ __volatile__(".byte 0xf2 ; lock ; cmpxchg %2, %1"
+  __asm__ __volatile__(".byte 0xf2 ; lock ; cmpxchg {%2, %1|%1, %2}"
                        : "+a" (_Comparand), "+m" (*_Destination)
                        : "r" (_Exchange) : "memory");
   return _Comparand;
 }
 static __inline__ long __DEFAULT_FN_ATTRS
 _InterlockedCompareExchange_HLERelease(long volatile *_Destination,
                               long _Exchange, long _Comparand) {
-  __asm__ __volatile__(".byte 0xf3 ; lock ; cmpxchg %2, %1"
+  __asm__ __volatile__(".byte 0xf3 ; lock ; cmpxchg {%2, %1|%1, %2}"
                        : "+a" (_Comparand), "+m" (*_Destination)
                        : "r" (_Exchange) : "memory");
   return _Comparand;
 }
 #endif
 #if defined(__x86_64__)
 static __inline__ __int64 __DEFAULT_FN_ATTRS
 _InterlockedCompareExchange64_HLEAcquire(__int64 volatile *_Destination,
                               __int64 _Exchange, __int64 _Comparand) {
-  __asm__ __volatile__(".byte 0xf2 ; lock ; cmpxchg %2, %1"
+  __asm__ __volatile__(".byte 0xf2 ; lock ; cmpxchg {%2, %1|%1, %2}"
                        : "+a" (_Comparand), "+m" (*_Destination)
                        : "r" (_Exchange) : "memory");
   return _Comparand;
 }
 static __inline__ __int64 __DEFAULT_FN_ATTRS
 _InterlockedCompareExchange64_HLERelease(__int64 volatile *_Destination,
                               __int64 _Exchange, __int64 _Comparand) {
-  __asm__ __volatile__(".byte 0xf3 ; lock ; cmpxchg %2, %1"
+  __asm__ __volatile__(".byte 0xf3 ; lock ; cmpxchg {%2, %1|%1, %2}"
                        : "+a" (_Comparand), "+m" (*_Destination)
                        : "r" (_Exchange) : "memory");
   return _Comparand;
 }
 #endif
 #ifdef __cplusplus
 }
 #endif
 
 #undef __DEFAULT_FN_ATTRS
 
 #endif /* defined(_MSC_VER) && __has_extension(gnu_asm) */
 
 #endif /* __IMMINTRIN_H */

clang/lib/Headers/intrin.h

static __inline__ void __DEFAULT_FN_ATTRS __movsb(unsigned char *__dst,
                                                   unsigned char const *__src,
                                                   size_t __n) {
 #if defined(__x86_64__)
   __asm__ __volatile__("rep movsb"
                        : "+D"(__dst), "+S"(__src), "+c"(__n)
                        :
                        : "memory");
 #else
-  __asm__ __volatile__("xchg %%esi, %1\nrep movsb\nxchg %%esi, %1"
+  __asm__ __volatile__("xchg {%%esi, %1|%1, esi}\n"
+                       "rep movsb\n"
+                       "xchg {%%esi, %1|%1, esi}"
                        : "+D"(__dst), "+r"(__src), "+c"(__n)
                        :
                        : "memory");
 #endif
 }
 static __inline__ void __DEFAULT_FN_ATTRS __movsd(unsigned long *__dst,
                                                   unsigned long const *__src,
                                                   size_t __n) {
 #if defined(__x86_64__)
-  __asm__ __volatile__("rep movsl"
+  __asm__ __volatile__("rep movs{l|d}"
                        : "+D"(__dst), "+S"(__src), "+c"(__n)
                        :
                        : "memory");
 #else
-  __asm__ __volatile__("xchg %%esi, %1\nrep movsl\nxchg %%esi, %1"
+  __asm__ __volatile__("xchg {%%esi, %1|%1, esi}\n"
+                       "rep movs{l|d}\n"
+                       "xchg {%%esi, %1|%1, esi}"
                        : "+D"(__dst), "+r"(__src), "+c"(__n)
                        :
                        : "memory");
 #endif
 }
 static __inline__ void __DEFAULT_FN_ATTRS __movsw(unsigned short *__dst,
                                                   unsigned short const *__src,
                                                   size_t __n) {
 #if defined(__x86_64__)
   __asm__ __volatile__("rep movsw"
                        : "+D"(__dst), "+S"(__src), "+c"(__n)
                        :
                        : "memory");
 #else
-  __asm__ __volatile__("xchg %%esi, %1\nrep movsw\nxchg %%esi, %1"
+  __asm__ __volatile__("xchg {%%esi, %1|%1, esi}\n"
+                       "rep movsw\n"
+                       "xchg {%%esi, %1|%1, esi}"
                        : "+D"(__dst), "+r"(__src), "+c"(__n)
                        :
                        : "memory");
 #endif
 }
 static __inline__ void __DEFAULT_FN_ATTRS __stosd(unsigned long *__dst,
                                                   unsigned long __x,
                                                   size_t __n) {
-  __asm__ __volatile__("rep stosl"
+  __asm__ __volatile__("rep stos{l|d}"
                        : "+D"(__dst), "+c"(__n)
                        : "a"(__x)
                        : "memory");
 }
 static __inline__ void __DEFAULT_FN_ATTRS __stosw(unsigned short *__dst,
                                                   unsigned short __x,
                                                   size_t __n) {
   __asm__ __volatile__("rep stosw"

 #if defined(__i386__)
 #define __cpuid_count(__leaf, __count, __eax, __ebx, __ecx, __edx)             \
   __asm("cpuid"                                                                \
         : "=a"(__eax), "=b"(__ebx), "=c"(__ecx), "=d"(__edx)                   \
         : "0"(__leaf), "2"(__count))
 #else
 /* x86-64 uses %rbx as the base register, so preserve it. */
 #define __cpuid_count(__leaf, __count, __eax, __ebx, __ecx, __edx)             \
-  __asm("xchgq %%rbx,%q1\n"                                                    \
+  __asm("xchg{q} {%%rbx, %q1|%q1, rbx}\n"                                      \
         "cpuid\n"                                                              \
-        "xchgq %%rbx,%q1"                                                      \
+        "xchg{q} {%%rbx, %q1|%q1, rbx}"                                        \
         : "=a"(__eax), "=r"(__ebx), "=c"(__ecx), "=d"(__edx)                   \
         : "0"(__leaf), "2"(__count))
 #endif
 static __inline__ void __DEFAULT_FN_ATTRS __cpuid(int __info[4], int __level) {
   __cpuid_count(__level, 0, __info[0], __info[1], __info[2], __info[3]);
 }
 static __inline__ void __DEFAULT_FN_ATTRS __cpuidex(int __info[4], int __level,
                                                     int __ecx) {
__readmsr(unsigned long __register) {
   unsigned long __eax;
   __asm__ ("rdmsr" : "=d"(__edx), "=a"(__eax) : "c"(__register));
   return (((unsigned __int64)__edx) << 32) | (unsigned __int64)__eax;
 }
 #endif
 
 static __inline__ unsigned __LPTRINT_TYPE__ __DEFAULT_FN_ATTRS __readcr3(void) {
   unsigned __LPTRINT_TYPE__ __cr3_val;
-  __asm__ __volatile__ ("mov %%cr3, %0" : "=r"(__cr3_val) : : "memory");
+  __asm__ __volatile__(
+                       "mov {%%cr3, %0|%0, cr3}"
+                       : "=r"(__cr3_val)
+                       :
+                       : "memory");
   return __cr3_val;
 }
 
 static __inline__ void __DEFAULT_FN_ATTRS
 __writecr3(unsigned __INTPTR_TYPE__ __cr3_val) {
-  __asm__ ("mov %0, %%cr3" : : "r"(__cr3_val) : "memory");
+  __asm__ ("mov {%0, %%cr3|cr3, %0}" : : "r"(__cr3_val) : "memory");
 }
 
 #ifdef __cplusplus
 }
 #endif
 
 #undef __LPTRINT_TYPE__
 
 #undef __DEFAULT_FN_ATTRS
 
 #endif /* __INTRIN_H */
 #endif /* _MSC_VER */

clang/lib/Headers/x86gprintrin.h

 #endif
 
 #if !(defined(_MSC_VER) || defined(__SCE__)) || __has_feature(modules) ||      \
     defined(__CRC32__)
 #include <crc32intrin.h>
 #endif
 
 #define __SSC_MARK(Tag)                                                        \
-  __asm__ __volatile__("movl %%ebx, %%eax; movl %0, %%ebx; .byte 0x64, 0x67, " \
-                       "0x90; movl %%eax, %%ebx;" ::"i"(Tag)                   \
+  __asm__ __volatile__("mov{l} {%%ebx, %%eax|eax, ebx}; "                      \
+                       "mov{l} {%0, %%ebx|ebx, %0}; "                          \
+                       ".byte 0x64, 0x67, 0x90; "                              \
+                       "mov{l} {%%eax, %%ebx|ebx, eax};" ::"i"(Tag)            \
                        : "%eax");
 
 #endif /* __X86GPRINTRIN_H */

clang/test/CodeGen/inline-asm-intel.c

+// REQUIRES: x86-registered-target
+
+/// Accept intel inline asm but write it out as att:
+// RUN: %clang_cc1 -Werror -target-feature +hreset -target-feature +pconfig -target-feature +sgx -ffreestanding -triple i386-unknown-unknown -mllvm -x86-asm-syntax=att -inline-asm=intel -O0 -S %s -o - | FileCheck --check-prefix=ATT %s
+// RUN: %clang_cc1 -Werror -target-feature +hreset -target-feature +pconfig -target-feature +sgx -ffreestanding -triple x86_64-unknown-unknown -mllvm -x86-asm-syntax=att -inline-asm=intel -O0 -S %s -o - | FileCheck --check-prefix=ATT %s
+
+/// Accept intel inline asm and write it out as intel:
+// RUN: %clang_cc1 -Werror -target-feature +hreset -target-feature +pconfig -target-feature +sgx -ffreestanding -triple i386-unknown-unknown -mllvm -x86-asm-syntax=intel -inline-asm=intel -O0 -S %s -o - | FileCheck  --check-prefix=INTEL %s
+// RUN: %clang_cc1 -Werror -target-feature +hreset -target-feature +pconfig -target-feature +sgx -ffreestanding -triple x86_64-unknown-unknown -mllvm -x86-asm-syntax=intel -inline-asm=intel -O0 -S %s -o - | FileCheck  --check-prefix=INTEL %s
+
+// RUN: %clang_cc1 -Werror -target-feature +hreset -target-feature +pconfig -target-feature +sgx -ffreestanding -triple i386-pc-win32 -mllvm -x86-asm-syntax=intel -inline-asm=intel -O0 -S %s -o - -fms-extensions -fms-compatibility -fms-compatibility-version=17.00 | FileCheck  --check-prefix=INTEL %s
+// RUN: %clang_cc1 -Werror -target-feature +hreset -target-feature +pconfig -target-feature +sgx -ffreestanding -triple x86_64-pc-win32 -mllvm -x86-asm-syntax=intel -inline-asm=intel -O0 -S %s -o - -fms-extensions -fms-compatibility -fms-compatibility-version=17.00 | FileCheck  --check-prefix=INTEL %s
+
+// Test that intrinsics headers still work with -masm=intel.
+#ifdef _MSC_VER
+#include <intrin.h>
+#else
+#include <x86intrin.h>
+#endif
+
+void f() {
+  // Intrinsic headers contain macros and inline functions.
+  // Inline assembly in both are checked only when they are
+  // referenced, so reference a few intrinsics here.
+  __SSC_MARK(4);
+  int a;
+  _hreset(a);
+  _pconfig_u32(0, (void*)0);
+
+  _encls_u32(0, (void*)0);
+  _enclu_u32(0, (void*)0);
+  _enclv_u32(0, (void*)0);
+#ifdef _MSC_VER
+  __movsb((void*)0, (void*)0, 0);
+  __movsd((void*)0, (void*)0, 0);
+  __movsw((void*)0, (void*)0, 0);
+  __stosb((void*)0, 0, 0);
+  __stosd((void*)0, 0, 0);
+  __stosw((void*)0, 0, 0);
+#ifdef __x86_64__
+  __movsq((void*)0, (void*)0, 0);
+  __stosq((void*)0, 0, 0);
+#endif
+  __cpuid((void*)0, 0);
+  __cpuidex((void*)0, 0, 0);
+  __halt();
+  __nop();
+  __readmsr(0);
+  __readcr3();
+  __writecr3(0);
+
+  _InterlockedExchange_HLEAcquire((void*)0, 0);
+  _InterlockedExchange_HLERelease((void*)0, 0);
+  _InterlockedCompareExchange_HLEAcquire((void*)0, 0, 0);
+  _InterlockedCompareExchange_HLERelease((void*)0, 0, 0);
+#ifdef __x86_64__
+  _InterlockedExchange64_HLEAcquire((void*)0, 0);
+  _InterlockedExchange64_HLERelease((void*)0, 0);
+  _InterlockedCompareExchange64_HLEAcquire((void*)0, 0, 0);
+  _InterlockedCompareExchange64_HLERelease((void*)0, 0, 0);
+#endif
+#endif
+
+
+  __asm__("mov eax, ebx");
+  // ATT: movl %ebx, %eax
+  // INTEL: mov eax, ebx
+
+  // Explicitly overriding asm style per block works:
+  __asm__(".att_syntax\nmovl %ebx, %eax");
+  // ATT: movl %ebx, %eax
+  // INTEL: mov eax, ebx
+
+  // The .att_syntax was only scoped to the previous statement.
+  // (This is different from gcc, where `.att_syntax` is in
+  // effect from that point on, so portable code would want an
+  // explicit `.intel_syntax noprefix\n` at the start of this string).
+  __asm__("mov eax, ebx");
+  // ATT: movl %ebx, %eax
+  // INTEL: mov eax, ebx
+}
+

clang/test/CodeGen/inline-asm-mixed-style.c

-// RUN: %clang_cc1 -triple i386-unknown-unknown -fasm-blocks -O0 -emit-llvm -S %s -o - | FileCheck %s
+// RUN: %clang_cc1 -ffreestanding -triple i386-unknown-unknown -fasm-blocks -O0 -emit-llvm -S %s -o - | FileCheck %s
+// RUN: %clang_cc1 -ffreestanding -triple x86_64-unknown-unknown -fasm-blocks -O0 -emit-llvm -S %s -o - | FileCheck %s
 // REQUIRES: x86-registered-target
 
+#include <immintrin.h>
+
 void f() {
   __asm mov eax, ebx
   __asm mov ebx, ecx
   __asm__("movl %ecx, %edx");
   // CHECK: movl    %ebx, %eax
   // CHECK: movl    %ecx, %ebx
   // CHECK: movl    %ecx, %edx
 

clang/test/CodeGen/ms-intrinsics-cpuid.c

void test__cpuid(int *info, int level) {
   __cpuid(info, level);
 }
 // X86-LABEL: define {{.*}} @test__cpuid(i32* %{{.*}}, i32 %{{.*}})
 // X86: call { i32, i32, i32, i32 } asm "cpuid",
 // X86-SAME:   "={ax},={bx},={cx},={dx},0,2,~{dirflag},~{fpsr},~{flags}"
 // X86-SAME:   (i32 %{{.*}}, i32 0)
 
 // X64-LABEL: define {{.*}} @test__cpuid(i32* %{{.*}}, i32 %{{.*}})
-// X64: call { i32, i32, i32, i32 } asm "xchgq %rbx{{.*}}cpuid{{.*}}xchgq %rbx{{.*}}",
+// X64: call { i32, i32, i32, i32 } asm "xchg$(q$) $(%rbx{{.*}}$){{.*}}cpuid{{.*}}xchg$(q$) $(%rbx{{.*}}$)",
 // X64-SAME:   "={ax},=r,={cx},={dx},0,2,~{dirflag},~{fpsr},~{flags}"
 // X64-SAME:   (i32 %{{.*}}, i32 0)

clang/test/CodeGen/ms-intrinsics.c

 // CHECK-X64:   tail call void @llvm.memset.p0i8.i64(i8* align 1 %Dest, i8 %Data, i64 %Count, i1 true)
 // CHECK-X64:   ret void
 // CHECK-X64: }
 
 void test__movsb(unsigned char *Dest, unsigned char *Src, size_t Count) {
   return __movsb(Dest, Src, Count);
 }
 // CHECK-I386-LABEL: define{{.*}} void @test__movsb
-// CHECK-I386:   tail call { i8*, i8*, i32 } asm sideeffect "xchg %esi, $1\0Arep movsb\0Axchg %esi, $1", "={di},=r,={cx},0,1,2,~{memory},~{dirflag},~{fpsr},~{flags}"(i8* %Dest, i8* %Src, i32 %Count)
+// CHECK-I386:   tail call { i8*, i8*, i32 } asm sideeffect "xchg $(%esi, $1$|$1, esi$)\0Arep movsb\0Axchg $(%esi, $1$|$1, esi$)", "={di},=r,={cx},0,1,2,~{memory},~{dirflag},~{fpsr},~{flags}"(i8* %Dest, i8* %Src, i32 %Count)
 // CHECK-I386:   ret void
 // CHECK-I386: }
 
 // CHECK-X64-LABEL: define{{.*}} void @test__movsb
 // CHECK-X64:   call { i8*, i8*, i64 } asm sideeffect "rep movsb", "={di},={si},={cx},0,1,2,~{memory},~{dirflag},~{fpsr},~{flags}"(i8* %Dest, i8* %Src, i64 %Count)
 // CHECK-X64:   ret void
 // CHECK-X64: }
 

 // CHECK-X64:   call { i16*, i64 } asm sideeffect "rep stosw", "={di},={cx},{ax},0,1,~{memory},~{dirflag},~{fpsr},~{flags}"(i16 %Data, i16* %Dest, i64 %Count)
 // CHECK-X64:   ret void
 // CHECK-X64: }
 
 void test__movsw(unsigned short *Dest, unsigned short *Src, size_t Count) {
   return __movsw(Dest, Src, Count);
 }
 // CHECK-I386-LABEL: define{{.*}} void @test__movsw
-// CHECK-I386:   tail call { i16*, i16*, i32 } asm sideeffect "xchg %esi, $1\0Arep movsw\0Axchg %esi, $1", "={di},=r,={cx},0,1,2,~{memory},~{dirflag},~{fpsr},~{flags}"(i16* %Dest, i16* %Src, i32 %Count)
+// CHECK-I386:   tail call { i16*, i16*, i32 } asm sideeffect "xchg $(%esi, $1$|$1, esi$)\0Arep movsw\0Axchg $(%esi, $1$|$1, esi$)", "={di},=r,={cx},0,1,2,~{memory},~{dirflag},~{fpsr},~{flags}"(i16* %Dest, i16* %Src, i32 %Count)
 // CHECK-I386:   ret void
 // CHECK-I386: }
 
 // CHECK-X64-LABEL: define{{.*}} void @test__movsw
 // CHECK-X64:   call { i16*, i16*, i64 } asm sideeffect "rep movsw", "={di},={si},={cx},0,1,2,~{memory},~{dirflag},~{fpsr},~{flags}"(i16* %Dest, i16* %Src, i64 %Count)
 // CHECK-X64:   ret void
 // CHECK-X64: }
 
 void test__stosd(unsigned long *Dest, unsigned long Data, size_t Count) {
   return __stosd(Dest, Data, Count);
 }
 // CHECK-I386-LABEL: define{{.*}} void @test__stosd
-// CHECK-I386:   call { i32*, i32 } asm sideeffect "rep stosl", "={di},={cx},{ax},0,1,~{memory},~{dirflag},~{fpsr},~{flags}"(i32 %Data, i32* %Dest, i32 %Count)
+// CHECK-I386:   call { i32*, i32 } asm sideeffect "rep stos$(l$|d$)", "={di},={cx},{ax},0,1,~{memory},~{dirflag},~{fpsr},~{flags}"(i32 %Data, i32* %Dest, i32 %Count)
 // CHECK-I386:   ret void
 // CHECK-I386: }
 
 // CHECK-X64-LABEL: define{{.*}} void @test__stosd
-// CHECK-X64:   call { i32*, i64 } asm sideeffect "rep stosl", "={di},={cx},{ax},0,1,~{memory},~{dirflag},~{fpsr},~{flags}"(i32 %Data, i32* %Dest, i64 %Count)
+// CHECK-X64:   call { i32*, i64 } asm sideeffect "rep stos$(l$|d$)", "={di},={cx},{ax},0,1,~{memory},~{dirflag},~{fpsr},~{flags}"(i32 %Data, i32* %Dest, i64 %Count)
 // CHECK-X64:   ret void
 // CHECK-X64: }
 
 void test__movsd(unsigned long *Dest, unsigned long *Src, size_t Count) {
   return __movsd(Dest, Src, Count);
 }
 // CHECK-I386-LABEL: define{{.*}} void @test__movsd
-// CHECK-I386:   tail call { i32*, i32*, i32 } asm sideeffect "xchg %esi, $1\0Arep movsl\0Axchg %esi, $1", "={di},=r,={cx},0,1,2,~{memory},~{dirflag},~{fpsr},~{flags}"(i32* %Dest, i32* %Src, i32 %Count)
+// CHECK-I386:   tail call { i32*, i32*, i32 } asm sideeffect "xchg $(%esi, $1$|$1, esi$)\0Arep movs$(l$|d$)\0Axchg $(%esi, $1$|$1, esi$)", "={di},=r,={cx},0,1,2,~{memory},~{dirflag},~{fpsr},~{flags}"(i32* %Dest, i32* %Src, i32 %Count)
 // CHECK-I386:   ret void
 // CHECK-I386: }
 
 // CHECK-X64-LABEL: define{{.*}} void @test__movsd
-// CHECK-X64:   call { i32*, i32*, i64 } asm sideeffect "rep movsl", "={di},={si},={cx},0,1,2,~{memory},~{dirflag},~{fpsr},~{flags}"(i32* %Dest, i32* %Src, i64 %Count)
+// CHECK-X64:   call { i32*, i32*, i64 } asm sideeffect "rep movs$(l$|d$)", "={di},={si},={cx},0,1,2,~{memory},~{dirflag},~{fpsr},~{flags}"(i32* %Dest, i32* %Src, i64 %Count)
 // CHECK-X64:   ret void
 // CHECK-X64: }
 
 #ifdef __x86_64__
 void test__stosq(unsigned __int64 *Dest, unsigned __int64 Data, size_t Count) {
   return __stosq(Dest, Data, Count);
 }
 // CHECK-X64-LABEL: define{{.*}} void @test__stosq

 // CHECK: ret i64 [[RESULT]]
 // CHECK: }
 
 #endif
 
 #if defined(__i386__) || defined(__x86_64__)
 long test_InterlockedExchange_HLEAcquire(long volatile *Target, long Value) {
 // CHECK-INTEL: define{{.*}} i32 @test_InterlockedExchange_HLEAcquire(i32*{{[a-z_ ]*}}%Target, i32{{[a-z_ ]*}}%Value)
-// CHECK-INTEL: call i32 asm sideeffect ".byte 0xf2 ; lock ; xchg $0, $1", "=r,=*m,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i32* %Target, i32 %Value, i32* %Target)
+// CHECK-INTEL: call i32 asm sideeffect ".byte 0xf2 ; lock ; xchg $($0, $1$|$1, $0$)", "=r,=*m,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i32* %Target, i32 %Value, i32* %Target)
   return _InterlockedExchange_HLEAcquire(Target, Value);
 }
 long test_InterlockedExchange_HLERelease(long volatile *Target, long Value) {
 // CHECK-INTEL: define{{.*}} i32 @test_InterlockedExchange_HLERelease(i32*{{[a-z_ ]*}}%Target, i32{{[a-z_ ]*}}%Value)
-// CHECK-INTEL: call i32 asm sideeffect ".byte 0xf3 ; lock ; xchg $0, $1", "=r,=*m,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i32* %Target, i32 %Value, i32* %Target)
+// CHECK-INTEL: call i32 asm sideeffect ".byte 0xf3 ; lock ; xchg $($0, $1$|$1, $0$)", "=r,=*m,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i32* %Target, i32 %Value, i32* %Target)
   return _InterlockedExchange_HLERelease(Target, Value);
 }
 long test_InterlockedCompareExchange_HLEAcquire(long volatile *Destination,
                                                 long Exchange, long Comparand) {
 // CHECK-INTEL: define{{.*}} i32 @test_InterlockedCompareExchange_HLEAcquire(i32*{{[a-z_ ]*}}%Destination, i32{{[a-z_ ]*}}%Exchange, i32{{[a-z_ ]*}}%Comparand)
-// CHECK-INTEL: call i32 asm sideeffect ".byte 0xf2 ; lock ; cmpxchg $2, $1", "={ax},=*m,r,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i32* %Destination, i32 %Exchange, i32 %Comparand, i32* %Destination)
+// CHECK-INTEL: call i32 asm sideeffect ".byte 0xf2 ; lock ; cmpxchg $($2, $1$|$1, $2$)", "={ax},=*m,r,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i32* %Destination, i32 %Exchange, i32 %Comparand, i32* %Destination)
   return _InterlockedCompareExchange_HLEAcquire(Destination, Exchange, Comparand);
 }
 long test_InterlockedCompareExchange_HLERelease(long volatile *Destination,
                                             long Exchange, long Comparand) {
 // CHECK-INTEL: define{{.*}} i32 @test_InterlockedCompareExchange_HLERelease(i32*{{[a-z_ ]*}}%Destination, i32{{[a-z_ ]*}}%Exchange, i32{{[a-z_ ]*}}%Comparand)
-// CHECK-INTEL: call i32 asm sideeffect ".byte 0xf3 ; lock ; cmpxchg $2, $1", "={ax},=*m,r,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i32* %Destination, i32 %Exchange, i32 %Comparand, i32* %Destination)
+// CHECK-INTEL: call i32 asm sideeffect ".byte 0xf3 ; lock ; cmpxchg $($2, $1$|$1, $2$)", "={ax},=*m,r,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i32* %Destination, i32 %Exchange, i32 %Comparand, i32* %Destination)
   return _InterlockedCompareExchange_HLERelease(Destination, Exchange, Comparand);
 }
 #endif
 #if defined(__x86_64__)
 __int64 test_InterlockedExchange64_HLEAcquire(__int64 volatile *Target, __int64 Value) {
 // CHECK-X64: define{{.*}} i64 @test_InterlockedExchange64_HLEAcquire(i64*{{[a-z_ ]*}}%Target, i64{{[a-z_ ]*}}%Value)
-// CHECK-X64: call i64 asm sideeffect ".byte 0xf2 ; lock ; xchg $0, $1", "=r,=*m,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i64* %Target, i64 %Value, i64* %Target)
+// CHECK-X64: call i64 asm sideeffect ".byte 0xf2 ; lock ; xchg $($0, $1$|$1, $0$)", "=r,=*m,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i64* %Target, i64 %Value, i64* %Target)
   return _InterlockedExchange64_HLEAcquire(Target, Value);
 }
 __int64 test_InterlockedExchange64_HLERelease(__int64 volatile *Target, __int64 Value) {
 // CHECK-X64: define{{.*}} i64 @test_InterlockedExchange64_HLERelease(i64*{{[a-z_ ]*}}%Target, i64{{[a-z_ ]*}}%Value)
-// CHECK-X64: call i64 asm sideeffect ".byte 0xf3 ; lock ; xchg $0, $1", "=r,=*m,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i64* %Target, i64 %Value, i64* %Target)
+// CHECK-X64: call i64 asm sideeffect ".byte 0xf3 ; lock ; xchg $($0, $1$|$1, $0$)", "=r,=*m,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i64* %Target, i64 %Value, i64* %Target)
   return _InterlockedExchange64_HLERelease(Target, Value);
 }
 __int64 test_InterlockedCompareExchange64_HLEAcquire(__int64 volatile *Destination,
                                                      __int64 Exchange, __int64 Comparand) {
 // CHECK-X64: define{{.*}} i64 @test_InterlockedCompareExchange64_HLEAcquire(i64*{{[a-z_ ]*}}%Destination, i64{{[a-z_ ]*}}%Exchange, i64{{[a-z_ ]*}}%Comparand)
-// CHECK-X64: call i64 asm sideeffect ".byte 0xf2 ; lock ; cmpxchg $2, $1", "={ax},=*m,r,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i64* %Destination, i64 %Exchange, i64 %Comparand, i64* %Destination)
+// CHECK-X64: call i64 asm sideeffect ".byte 0xf2 ; lock ; cmpxchg $($2, $1$|$1, $2$)", "={ax},=*m,r,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i64* %Destination, i64 %Exchange, i64 %Comparand, i64* %Destination)
   return _InterlockedCompareExchange64_HLEAcquire(Destination, Exchange, Comparand);
 }
 __int64 test_InterlockedCompareExchange64_HLERelease(__int64 volatile *Destination,
                                                      __int64 Exchange, __int64 Comparand) {
 // CHECK-X64: define{{.*}} i64 @test_InterlockedCompareExchange64_HLERelease(i64*{{[a-z_ ]*}}%Destination, i64{{[a-z_ ]*}}%Exchange, i64{{[a-z_ ]*}}%Comparand)
-// CHECK-X64: call i64 asm sideeffect ".byte 0xf3 ; lock ; cmpxchg $2, $1", "={ax},=*m,r,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i64* %Destination, i64 %Exchange, i64 %Comparand, i64* %Destination)
+// CHECK-X64: call i64 asm sideeffect ".byte 0xf3 ; lock ; cmpxchg $($2, $1$|$1, $2$)", "={ax},=*m,r,0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(i64* %Destination, i64 %Exchange, i64 %Comparand, i64* %Destination)
   return _InterlockedCompareExchange64_HLERelease(Destination, Exchange, Comparand);
 }
 #endif
 
 #if defined(__arm__) || defined(__aarch64__)
 char test_InterlockedExchangeAdd8_acq(char volatile *value, char mask) {
   return _InterlockedExchangeAdd8_acq(value, mask);
 }

clang/test/Driver/masm.c

 // RUN: %clang -target i386-unknown-linux -masm=intel -S %s -### 2>&1 | FileCheck --check-prefix=CHECK-INTEL %s
 // RUN: %clang -target i386-unknown-linux -masm=att -S %s -### 2>&1 | FileCheck --check-prefix=CHECK-ATT %s
 // RUN: %clang -target i386-unknown-linux -S -masm=somerequired %s -### 2>&1 | FileCheck --check-prefix=CHECK-SOMEREQUIRED %s
 // RUN: %clang -target arm-unknown-eabi -S -masm=intel %s -### 2>&1 | FileCheck --check-prefix=CHECK-ARM %s
 // RUN: %clang_cl --target=x86_64 /FA -### -- %s 2>&1 | FileCheck --check-prefix=CHECK-CL %s
 
 int f() {
 // CHECK-INTEL: -x86-asm-syntax=intel
+// CHECK-INTEL: -inline-asm=intel
 // CHECK-ATT: -x86-asm-syntax=att
+// CHECK-ATT: -inline-asm=att
 // CHECK-SOMEREQUIRED: error: unsupported argument 'somerequired' to option 'masm='
 // CHECK-ARM: warning: argument unused during compilation: '-masm=intel'
 // CHECK-CL: -x86-asm-syntax=intel
+// CHECK-CL-NOT: -inline-asm=intel
   return 0;
 }