[PowerPC] Remove zexts after byte-swapping loads
lhbrx and lwbrx not only load their data with byte swapping, but also clear the
upper 32 bits (at least). As a result, they can be added to the PPCISelDAGToDAG
peephole optimization as frontier instructions for the removal of unnecessary
zero extensions.
llvm-svn: 225189
diff --git a/llvm/lib/Target/PowerPC/PPCInstr64Bit.td b/llvm/lib/Target/PowerPC/PPCInstr64Bit.td
index 75f4656..29b13f8 100644
--- a/llvm/lib/Target/PowerPC/PPCInstr64Bit.td
+++ b/llvm/lib/Target/PowerPC/PPCInstr64Bit.td
@@ -843,6 +843,13 @@
"ldbrx $rD, $src", IIC_LdStLoad,
[(set i64:$rD, (PPClbrx xoaddr:$src, i64))]>, isPPC64;
+let mayLoad = 1, hasSideEffects = 0, isCodeGenOnly = 1 in {
+def LHBRX8 : XForm_1<31, 790, (outs g8rc:$rD), (ins memrr:$src),
+ "lhbrx $rD, $src", IIC_LdStLoad, []>;
+def LWBRX8 : XForm_1<31, 534, (outs g8rc:$rD), (ins memrr:$src),
+ "lwbrx $rD, $src", IIC_LdStLoad, []>;
+}
+
let mayLoad = 1, hasSideEffects = 0 in {
def LDU : DSForm_1<58, 1, (outs g8rc:$rD, ptr_rc_nor0:$ea_result), (ins memrix:$addr),
"ldu $rD, $addr", IIC_LdStLDU,