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
diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
index 581be1f..7089c1f 100644
--- a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -770,6 +770,7 @@
return getSTI().getFeatureBits()[X86::Mode16Bit];
}
void SwitchMode(unsigned mode) {
+ MCSubtargetInfo &STI = copySTI();
FeatureBitset AllModes({X86::Mode64Bit, X86::Mode32Bit, X86::Mode16Bit});
FeatureBitset OldMode = STI.getFeatureBits() & AllModes;
unsigned FB = ComputeAvailableFeatures(
@@ -799,7 +800,7 @@
/// }
public:
- X86AsmParser(MCSubtargetInfo &sti, MCAsmParser &Parser,
+ X86AsmParser(const MCSubtargetInfo &sti, MCAsmParser &Parser,
const MCInstrInfo &mii, const MCTargetOptions &Options)
: MCTargetAsmParser(Options, sti), MII(mii), InstInfo(nullptr) {