[mips] Remap move as or.
Summary:
This patch remaps the assembly idiom 'move' to 'or' instead of 'daddu' or
'addu'. The use of addu/daddu instead of or as move was highlighted as a
performance issue during the analysis of a recent 64bit design. Originally
move was encoded as 'or' by binutils but was changed for the r10k cpu family
due to their pipeline which had 2 arithmetic units and a single logical unit,
and so could issue multiple (d)addu based moves at the same time but only 1
logical move.
This patch preserves the disassembly behaviour so that disassembling a old style
(d)addu move still appears as move, but assembling move always gives an or
Patch by Simon Dardis.
Reviewers: vkalintiris
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D11796
llvm-svn: 244579
diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp b/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
index e4da2df..dc4673d 100644
--- a/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
+++ b/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
@@ -766,7 +766,7 @@
// Either store the old $gp in a register or on the stack
if (IsReg) {
// move $save, $gpreg
- Inst.setOpcode(Mips::DADDu);
+ Inst.setOpcode(Mips::OR64);
Inst.addOperand(MCOperand::createReg(RegOrOffset));
Inst.addOperand(MCOperand::createReg(Mips::GP));
Inst.addOperand(MCOperand::createReg(Mips::ZERO));