Add micro-optimization which allows us to fold imm into cmp. This allows us to save 1 word (sometimes) and reduce register pressure.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93551 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/MSP430/MSP430ISelLowering.cpp b/lib/Target/MSP430/MSP430ISelLowering.cpp
index d3dce4b..d1ce3cf 100644
--- a/lib/Target/MSP430/MSP430ISelLowering.cpp
+++ b/lib/Target/MSP430/MSP430ISelLowering.cpp
@@ -675,21 +675,53 @@
case ISD::SETULE:
std::swap(LHS, RHS); // FALLTHROUGH
case ISD::SETUGE:
+ // Turn lhs u>= rhs with lhs constant into rhs u< lhs+1, this allows us to
+ // fold constant into instruction.
+ if (const ConstantSDNode * C = dyn_cast<ConstantSDNode>(LHS)) {
+ LHS = RHS;
+ RHS = DAG.getConstant(C->getSExtValue() + 1, C->getValueType(0));
+ TCC = MSP430CC::COND_LO;
+ break;
+ }
TCC = MSP430CC::COND_HS; // aka COND_C
break;
case ISD::SETUGT:
std::swap(LHS, RHS); // FALLTHROUGH
case ISD::SETULT:
+ // Turn lhs u< rhs with lhs constant into rhs u>= lhs+1, this allows us to
+ // fold constant into instruction.
+ if (const ConstantSDNode * C = dyn_cast<ConstantSDNode>(LHS)) {
+ LHS = RHS;
+ RHS = DAG.getConstant(C->getSExtValue() + 1, C->getValueType(0));
+ TCC = MSP430CC::COND_HS;
+ break;
+ }
TCC = MSP430CC::COND_LO; // aka COND_NC
break;
case ISD::SETLE:
std::swap(LHS, RHS); // FALLTHROUGH
case ISD::SETGE:
+ // Turn lhs >= rhs with lhs constant into rhs < lhs+1, this allows us to
+ // fold constant into instruction.
+ if (const ConstantSDNode * C = dyn_cast<ConstantSDNode>(LHS)) {
+ LHS = RHS;
+ RHS = DAG.getConstant(C->getSExtValue() + 1, C->getValueType(0));
+ TCC = MSP430CC::COND_L;
+ break;
+ }
TCC = MSP430CC::COND_GE;
break;
case ISD::SETGT:
std::swap(LHS, RHS); // FALLTHROUGH
case ISD::SETLT:
+ // Turn lhs < rhs with lhs constant into rhs >= lhs+1, this allows us to
+ // fold constant into instruction.
+ if (const ConstantSDNode * C = dyn_cast<ConstantSDNode>(LHS)) {
+ LHS = RHS;
+ RHS = DAG.getConstant(C->getSExtValue() + 1, C->getValueType(0));
+ TCC = MSP430CC::COND_GE;
+ break;
+ }
TCC = MSP430CC::COND_L;
break;
}