Add ori reg, reg, 0 as a move instruction. This can be generated from

loading a 32bit constant into a register whose low halfword is all zeroes.

We now omit the ori after the lis for the following C code:

int bar(int y) { return y * 0x00F0000; }

_bar:
.LBB_bar_0:     ; entry
        ; IMPLICIT_DEF
        lis r2, 15
        mullw r3, r3, r2
        blr

llvm-svn: 16825

1 files changed, 11 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPC32InstrInfo.cpp b/llvm/lib/Target/PowerPC/PPC32InstrInfo.cpp
index ceb4d5044f4..ec25239721d 100644
--- a/llvm/lib/Target/PowerPC/PPC32InstrInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPC32InstrInfo.cpp
@@ -46,6 +46,17 @@ bool PPC32InstrInfo::isMoveInstr(const MachineInstr& MI,
       destReg = MI.getOperand(0).getReg();
       return true;
     }
+  } else if (oc == PPC::ORI) {             // ori r1, r2, 0
+    assert(MI.getNumOperands() == 3 &&
+           MI.getOperand(0).isRegister() &&
+           MI.getOperand(1).isRegister() &&
+           MI.getOperand(2).isImmediate() &&
+           "invalid PPC ORI instruction!");
+    if (MI.getOperand(2).getImmedValue()==0) {
+      sourceReg = MI.getOperand(1).getReg();
+      destReg = MI.getOperand(0).getReg();
+      return true;
+    }
   } else if (oc == PPC::FMR) {              // fmr r1, r2
     assert(MI.getNumOperands() == 2 &&
            MI.getOperand(0).isRegister() &&