[MC] Add assembler support for .cg_profile.

Object FIle Representation
At codegen time this is emitted into the ELF file a pair of symbol indices and a weight. In assembly it looks like:

.cg_profile a, b, 32
.cg_profile freq, a, 11
.cg_profile freq, b, 20

When writing an ELF file these are put into a SHT_LLVM_CALL_GRAPH_PROFILE (0x6fff4c02) section as (uint32_t, uint32_t, uint64_t) tuples as (from symbol index, to symbol index, weight).

Differential Revision: https://reviews.llvm.org/D44965

llvm-svn: 333823

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
index d19c8c21dd0..5c7bbeafec2 100644
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -304,6 +304,9 @@ public:
                         SMLoc Loc) override;
   void EmitWinEHHandlerData(SMLoc Loc) override;
 
+  void emitCGProfileEntry(const MCSymbolRefExpr *From,
+                          const MCSymbolRefExpr *To, uint64_t Count) override;
+
   void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
                        bool PrintSchedInfo) override;
 
@@ -1650,6 +1653,17 @@ void MCAsmStreamer::EmitWinCFIEndProlog(SMLoc Loc) {
   EmitEOL();
 }
 
+void MCAsmStreamer::emitCGProfileEntry(const MCSymbolRefExpr *From,
+                                       const MCSymbolRefExpr *To,
+                                       uint64_t Count) {
+  OS << "\t.cg_profile ";
+  From->getSymbol().print(OS, MAI);
+  OS << ", ";
+  To->getSymbol().print(OS, MAI);
+  OS << ", " << Count;
+  EmitEOL();
+}
+
 void MCAsmStreamer::AddEncodingComment(const MCInst &Inst,
                                        const MCSubtargetInfo &STI,
                                        bool PrintSchedInfo) {