Enable assembly output of local commons for AIX

Summary:
This patch enable assembly output of local commons for AIX using .lcomm
directives. Adds a EmitXCOFFLocalCommonSymbol to MCStreamer so we can emit the
AIX version of .lcomm assembly directives which include a csect name. Handle the
case of BSS locals in PPCAIXAsmPrinter by using EmitXCOFFLocalCommonSymbol. Adds
a test for generating .lcomm on AIX Targets.

Reviewers: cebowleratibm, hubert.reinterpretcast, Xiangling_L, jasonliu, sfertile

Reviewed By: sfertile

Subscribers: wuzish, nemanjai, hiraditya, kbarton, MaskRay, jsji, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64825

llvm-svn: 368306

1 files changed, 20 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
index c0890b59fe3..967ee8b3c5f 100644
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -162,6 +162,8 @@ public:
   void EmitCOFFSectionIndex(MCSymbol const *Symbol) override;
   void EmitCOFFSecRel32(MCSymbol const *Symbol, uint64_t Offset) override;
   void EmitCOFFImgRel32(MCSymbol const *Symbol, int64_t Offset) override;
+  void EmitXCOFFLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                  unsigned ByteAlign) override;
   void emitELFSize(MCSymbol *Symbol, const MCExpr *Value) override;
   void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                         unsigned ByteAlignment) override;
@@ -757,6 +759,24 @@ void MCAsmStreamer::EmitCOFFImgRel32(MCSymbol const *Symbol, int64_t Offset) {
   EmitEOL();
 }
 
+// We need an XCOFF specific version of this directive as the AIX syntax
+// requires a QualName argument identifying the csect name and storage mapping
+// class to appear before the alignment if we are specifying it.
+void MCAsmStreamer::EmitXCOFFLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                               unsigned ByteAlignment) {
+  assert(MAI->getLCOMMDirectiveAlignmentType() == LCOMM::Log2Alignment &&
+         "We only support writing log base-2 alignment format with XCOFF");
+  assert(isPowerOf2_32(ByteAlignment) && "alignment must be a power of 2");
+
+  OS << "\t.lcomm\t";
+  Symbol->print(OS, MAI);
+  OS << ',' << Size;
+  OS << ',' << Symbol->getName();
+  OS << ',' << Log2_32(ByteAlignment);
+
+  EmitEOL();
+}
+
 void MCAsmStreamer::emitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
   assert(MAI->hasDotTypeDotSizeDirective());
   OS << "\t.size\t";