[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

1 files changed, 5 insertions, 5 deletions

diff --git a/llvm/lib/Target/Mips/MipsSEFrameLowering.cpp b/llvm/lib/Target/Mips/MipsSEFrameLowering.cpp
index a19d1504e1e..5b4608fad2b 100644
--- a/llvm/lib/Target/Mips/MipsSEFrameLowering.cpp
+++ b/llvm/lib/Target/Mips/MipsSEFrameLowering.cpp
@@ -381,7 +381,7 @@ void MipsSEFrameLowering::emitPrologue(MachineFunction &MF,
   unsigned SP = ABI.GetStackPtr();
   unsigned FP = ABI.GetFramePtr();
   unsigned ZERO = ABI.GetNullPtr();
-  unsigned ADDu = ABI.GetPtrAdduOp();
+  unsigned MOVE = ABI.GetGPRMoveOp();
   unsigned ADDiu = ABI.GetPtrAddiuOp();
   unsigned AND = ABI.IsN64() ? Mips::AND64 : Mips::AND;
 
@@ -491,7 +491,7 @@ void MipsSEFrameLowering::emitPrologue(MachineFunction &MF,
   // if framepointer enabled, set it to point to the stack pointer.
   if (hasFP(MF)) {
     // Insert instruction "move $fp, $sp" at this location.
-    BuildMI(MBB, MBBI, dl, TII.get(ADDu), FP).addReg(SP).addReg(ZERO)
+    BuildMI(MBB, MBBI, dl, TII.get(MOVE), FP).addReg(SP).addReg(ZERO)
       .setMIFlag(MachineInstr::FrameSetup);
 
     // emit ".cfi_def_cfa_register $fp"
@@ -514,7 +514,7 @@ void MipsSEFrameLowering::emitPrologue(MachineFunction &MF,
       if (hasBP(MF)) {
         // move $s7, $sp
         unsigned BP = STI.isABI_N64() ? Mips::S7_64 : Mips::S7;
-        BuildMI(MBB, MBBI, dl, TII.get(ADDu), BP)
+        BuildMI(MBB, MBBI, dl, TII.get(MOVE), BP)
           .addReg(SP)
           .addReg(ZERO);
       }
@@ -538,7 +538,7 @@ void MipsSEFrameLowering::emitEpilogue(MachineFunction &MF,
   unsigned SP = ABI.GetStackPtr();
   unsigned FP = ABI.GetFramePtr();
   unsigned ZERO = ABI.GetNullPtr();
-  unsigned ADDu = ABI.GetPtrAdduOp();
+  unsigned MOVE = ABI.GetGPRMoveOp();
 
   // if framepointer enabled, restore the stack pointer.
   if (hasFP(MF)) {
@@ -549,7 +549,7 @@ void MipsSEFrameLowering::emitEpilogue(MachineFunction &MF,
       --I;
 
     // Insert instruction "move $sp, $fp" at this location.
-    BuildMI(MBB, I, dl, TII.get(ADDu), SP).addReg(FP).addReg(ZERO);
+    BuildMI(MBB, I, dl, TII.get(MOVE), SP).addReg(FP).addReg(ZERO);
   }
 
   if (MipsFI->callsEhReturn()) {