[DEBUGINFO, NVPTX] Try to pack bytes data into a single string.

Summary:
If the target does not support `.asciz` and `.ascii` directives, the
strings are represented as bytes and each byte is placed on the new line
as a separate byte directive `.b8 <data>`. NVPTX target allows to
represent the vector of the data of the same type as a vector, where
values are separated using `,` symbol: `.b8 <data1>,<data2>,...`. This
allows to reduce the size of the final PTX file. Ptxas tool includes ptx
files into the resulting binary object, so reducing the size of the PTX
file is important.

Reviewers: tra, jlebar, echristo

Subscribers: jholewinski, llvm-commits

Differential Revision: https://reviews.llvm.org/D45822

llvm-svn: 345142

2 files changed, 20 insertions, 4 deletions

diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
index c4744ac5d51..f75a8e077e4 100644
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -858,10 +858,14 @@ void MCAsmStreamer::EmitBytes(StringRef Data) {
   // supported, emit as vector of 8bits data.
   if (Data.size() == 1 ||
       !(MAI->getAscizDirective() || MAI->getAsciiDirective())) {
-    const char *Directive = MAI->getData8bitsDirective();
-    for (const unsigned char C : Data.bytes()) {
-      OS << Directive << (unsigned)C;
-      EmitEOL();
+    if (MCTargetStreamer *TS = getTargetStreamer()) {
+      TS->emitRawBytes(Data);
+    } else {
+      const char *Directive = MAI->getData8bitsDirective();
+      for (const unsigned char C : Data.bytes()) {
+        OS << Directive << (unsigned)C;
+        EmitEOL();
+      }
     }
     return;
   }
diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
index bfcf6d47a78..1b704b89320 100644
--- a/llvm/lib/MC/MCStreamer.cpp
+++ b/llvm/lib/MC/MCStreamer.cpp
@@ -72,6 +72,18 @@ void MCTargetStreamer::emitValue(const MCExpr *Value) {
   Streamer.EmitRawText(OS.str());
 }
 
+void MCTargetStreamer::emitRawBytes(StringRef Data) {
+  const MCAsmInfo *MAI = Streamer.getContext().getAsmInfo();
+  const char *Directive = MAI->getData8bitsDirective();
+  for (const unsigned char C : Data.bytes()) {
+    SmallString<128> Str;
+    raw_svector_ostream OS(Str);
+
+    OS << Directive << (unsigned)C;
+    Streamer.EmitRawText(OS.str());
+  }
+}
+
 void MCTargetStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {}
 
 MCStreamer::MCStreamer(MCContext &Ctx)