[PowerPC] Remove zexts after i32 ctlz
The 64-bit semantics of cntlzw are not special, the 32-bit population count is
stored as a 64-bit value in the range [0,32]. As a result, it is always zero
extended, and it can be added to the PPCISelDAGToDAG peephole optimization as a
frontier instruction for the removal of unnecessary zero extensions.
llvm-svn: 225192
diff --git a/llvm/lib/Target/PowerPC/PPCInstr64Bit.td b/llvm/lib/Target/PowerPC/PPCInstr64Bit.td
index 29b13f8..1b6fcbe 100644
--- a/llvm/lib/Target/PowerPC/PPCInstr64Bit.td
+++ b/llvm/lib/Target/PowerPC/PPCInstr64Bit.td
@@ -551,7 +551,10 @@
"srad", "$rA, $rS, $rB", IIC_IntRotateD,
[(set i64:$rA, (PPCsra i64:$rS, i32:$rB))]>, isPPC64;
-let Interpretation64Bit = 1, isCodeGenOnly = 1 in {
+let Interpretation64Bit = 1, isCodeGenOnly = 1 in {
+defm CNTLZW8 : XForm_11r<31, 26, (outs g8rc:$rA), (ins g8rc:$rS),
+ "cntlzw", "$rA, $rS", IIC_IntGeneral, []>;
+
defm EXTSB8 : XForm_11r<31, 954, (outs g8rc:$rA), (ins g8rc:$rS),
"extsb", "$rA, $rS", IIC_IntSimple,
[(set i64:$rA, (sext_inreg i64:$rS, i8))]>;