Fold TRUNCATE (LOAD P) into a smaller load from P.
llvm-svn: 19494
diff --git a/llvm/lib/Target/X86/X86ISelPattern.cpp b/llvm/lib/Target/X86/X86ISelPattern.cpp
index dacd513..34d1356 100644
--- a/llvm/lib/Target/X86/X86ISelPattern.cpp
+++ b/llvm/lib/Target/X86/X86ISelPattern.cpp
@@ -410,6 +410,7 @@
Result = MaxRegUse+NumExtraMaxRegUsers;
}
+
//std::cerr << " WEIGHT: " << Result << " "; N->dump(); std::cerr << "\n";
return Result;
}
@@ -1106,6 +1107,20 @@
return Result;
}
case ISD::TRUNCATE:
+ // Fold TRUNCATE (LOAD P) into a smaller load from P.
+ if (isFoldableLoad(N.getOperand(0))) {
+ switch (N.getValueType()) {
+ default: assert(0 && "Unknown truncate!");
+ case MVT::i1:
+ case MVT::i8: Opc = X86::MOV8rm; break;
+ case MVT::i16: Opc = X86::MOV16rm; break;
+ }
+ X86AddressMode AM;
+ EmitFoldedLoad(N.getOperand(0), AM);
+ addFullAddress(BuildMI(BB, Opc, 4, Result), AM);
+ return Result;
+ }
+
// Handle cast of LARGER int to SMALLER int using a move to EAX followed by
// a move out of AX or AL.
switch (N.getOperand(0).getValueType()) {