[XCOFF] ignore the cold attribute.

[Esme]

Summary

AIX assembly doesn't support the cold feature.
While it shouldn't be a function error when XCOFF catching the cold attribute.
As with the behavior of other formats, we just ignore the attribute for now.

[DiggerLin]

llvm/lib/MC/MCXCOFFStreamer.cpp

40

prefer to add comment here .
MCXCOFFStreamer will be called when generate the xcoff object file.
so "AIX XCOFF doesn't support the cold feature" instead of AIX "assembly doesn't support the cold feature." ?

[Esme]

llvm/lib/MC/MCXCOFFStreamer.cpp

40

Addressed. Thanks.

[DiggerLin]

LGTM

llvm/test/CodeGen/PowerPC/aix-xcoff-cold.ll

10

nit: delete the last line ? for the last line not related to the cold attribute, and deleting the line will make the test case more simple and readable.

llvm/lib/MC/MCXCOFFStreamer.cpp

: MCObjectStreamer(Context, std::move(MAB), std::move(OW),
                        std::move(Emitter)) {}
 
 bool MCXCOFFStreamer::emitSymbolAttribute(MCSymbol *Sym,
                                           MCSymbolAttr Attribute) {
   auto *Symbol = cast<MCSymbolXCOFF>(Sym);
   getAssembler().registerSymbol(*Symbol);
 
   switch (Attribute) {
+  // XCOFF doesn't support the cold feature.
+  case MCSA_Cold:
+    return false;
+
   case MCSA_Global:
   case MCSA_Extern:
     Symbol->setStorageClass(XCOFF::C_EXT);
     Symbol->setExternal(true);
     break;
   case MCSA_LGlobal:
     Symbol->setStorageClass(XCOFF::C_HIDEXT);
     Symbol->setExternal(true);

llvm/test/CodeGen/PowerPC/aix-xcoff-cold.ll

+; RUN: llc -mtriple powerpc64-ibm-aix-xcoff -filetype=obj -o %t.o < %s
+; RUN: llvm-objdump --syms %t.o | FileCheck %s
+
+; CHECK:      SYMBOL TABLE:
+; CHECK-NEXT: 0000000000000000      df *DEBUG* 0000000000000000 <stdin>
+; CHECK-NEXT: 0000000000000000 l       .text   000000000000001e .text
+; CHECK-NEXT: 0000000000000000 g     F .text (csect: .text)  0000000000000000 .cold_fun
+; CHECK-NEXT: 0000000000000020 g     O .data   0000000000000018 cold_fun
+
+define dso_local void @cold_fun() #1 {
+entry:
+  ret void
+}
+
+attributes #1 = { cold }