Reduce the size of MCRelaxableFragment.

MCRelaxableFragment previously kept a copy of MCSubtargetInfo and
MCInst to enable re-encoding the MCInst later during relaxation. A copy
of MCSubtargetInfo (instead of a reference or pointer) was needed
because the feature bits could be modified by the parser.

This commit replaces the MCSubtargetInfo copy in MCRelaxableFragment
with a constant reference to MCSubtargetInfo. The copies of
MCSubtargetInfo are kept in MCContext, and the target parsers are now
responsible for asking MCContext to provide a copy whenever the feature
bits of MCSubtargetInfo have to be toggled.
 
With this patch, I saw a 4% reduction in peak memory usage when I
compiled verify-uselistorder.lto.bc using llc.

rdar://problem/21736951

Differential Revision: http://reviews.llvm.org/D14346

llvm-svn: 253127

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Target/Sparc/AsmParser/SparcAsmParser.cpp b/llvm/lib/Target/Sparc/AsmParser/SparcAsmParser.cpp
index c739efb7814..a55274744fd 100644
--- a/llvm/lib/Target/Sparc/AsmParser/SparcAsmParser.cpp
+++ b/llvm/lib/Target/Sparc/AsmParser/SparcAsmParser.cpp
@@ -88,7 +88,7 @@ class SparcAsmParser : public MCTargetAsmParser {
                  SmallVectorImpl<MCInst> &Instructions);
 
 public:
-  SparcAsmParser(MCSubtargetInfo &sti, MCAsmParser &parser,
+  SparcAsmParser(const MCSubtargetInfo &sti, MCAsmParser &parser,
                 const MCInstrInfo &MII,
                 const MCTargetOptions &Options)
       : MCTargetAsmParser(Options, sti), Parser(parser) {