[llvm] [MC][AArch64][ARM][X86] Push target-dependent assembler flags into targets (PR #139844)

[Fangrui Song via llvm-commits]

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@@ -918,8 +918,11 @@ void X86AsmPrinter::emitStartOfAsmFile(Module &M) {
   // If this is not inline asm and we're in 16-bit
   // mode prefix assembly with .code16.
   bool is16 = TT.getEnvironment() == Triple::CODE16;
-  if (M.getModuleInlineAsm().empty() && is16)
-    OutStreamer->emitAssemblerFlag(MCAF_Code16);
+  if (M.getModuleInlineAsm().empty() && is16) {
+    auto *XTS =
+        static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer());
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MaskRay wrote:

X86AsmPrinter should probably define a convenience method that returns X86TargetStreamer

https://github.com/llvm/llvm-project/pull/139844