From 0c1ba91a54e7088fab3a3b9820f8b8366be0e11b Mon Sep 17 00:00:00 2001 From: Anton Korobeynikov Date: Fri, 15 Jan 2010 21:18:02 +0000 Subject: [PATCH] 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 --- lib/Target/MSP430/MSP430ISelLowering.cpp | 32 ++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/lib/Target/MSP430/MSP430ISelLowering.cpp b/lib/Target/MSP430/MSP430ISelLowering.cpp index d3dce4b4ba2..d1ce3cfe99c 100644 --- a/lib/Target/MSP430/MSP430ISelLowering.cpp +++ b/lib/Target/MSP430/MSP430ISelLowering.cpp @@ -675,21 +675,53 @@ static SDValue EmitCMP(SDValue &LHS, SDValue &RHS, SDValue &TargetCC, 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(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(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(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(LHS)) { + LHS = RHS; + RHS = DAG.getConstant(C->getSExtValue() + 1, C->getValueType(0)); + TCC = MSP430CC::COND_GE; + break; + } TCC = MSP430CC::COND_L; break; } -- 2.34.1