Commit a small improvement that is already in the x86 and ia64 backends to
not generate unnecessary register copies. This improves compile time by
2-5% depending on the test.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22210 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCISelPattern.cpp b/lib/Target/PowerPC/PPCISelPattern.cpp
index 750161c..5b4c6e5 100644
--- a/lib/Target/PowerPC/PPCISelPattern.cpp
+++ b/lib/Target/PowerPC/PPCISelPattern.cpp
@@ -1572,6 +1572,11 @@
SDNode *Node = N.Val;
MVT::ValueType DestType = N.getValueType();
+ if (Node->getOpcode() == ISD::CopyFromReg &&
+ MRegisterInfo::isVirtualRegister(cast<RegSDNode>(Node)->getReg()))
+ // Just use the specified register as our input.
+ return cast<RegSDNode>(Node)->getReg();
+
unsigned &Reg = ExprMap[N];
if (Reg) return Reg;