[llvm] [MC][X86/M68k] Emit syntax directive for AT&T (PR #167234)

[Fangrui Song via llvm-commits]

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@@ -190,7 +190,11 @@ void M68kAsmPrinter::emitFunctionBodyStart() {}
 void M68kAsmPrinter::emitFunctionBodyEnd() {}
 
 void M68kAsmPrinter::emitStartOfAsmFile(Module &M) {
-  OutStreamer->emitSyntaxDirective();
+  // m68k assemblers generally don't support .att_syntax so we only emit the
+  // directive for Intel syntax.
+  if (MAI->getAssemblerDialect() == InlineAsm::AD_Intel) {
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MaskRay wrote:

I am not familiar with m68k, but does `AD_Intel` actually make sense or should we just use a constant here?

https://github.com/llvm/llvm-project/pull/167234