From d51425a82da3d519b85f86e380358aa22e63442d Mon Sep 17 00:00:00 2001 From: Evan Cheng Date: Thu, 16 Feb 2006 01:50:02 +0000 Subject: [PATCH] Use movaps / movapd (instead of movss / movsd) to do FR32 / FR64 reg to reg transfer. According to the Intel P4 Optimization Manual: Moves that write a portion of a register can introduce unwanted dependences. The movsd reg, reg instruction writes only the bottom 64 bits of a register, not to all 128 bits. This introduces a dependence on the preceding instruction that produces the upper 64 bits (even if those bits are not longer wanted). The dependence inhibits register renaming, and thereby reduces parallelism. Not to mention movaps is shorter than movss. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26226 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/X86/X86RegisterInfo.cpp | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/Target/X86/X86RegisterInfo.cpp b/lib/Target/X86/X86RegisterInfo.cpp index fdbe4225a06..571bef18db6 100644 --- a/lib/Target/X86/X86RegisterInfo.cpp +++ b/lib/Target/X86/X86RegisterInfo.cpp @@ -106,9 +106,9 @@ void X86RegisterInfo::copyRegToReg(MachineBasicBlock &MBB, } else if (RC == &X86::RFPRegClass || RC == &X86::RSTRegClass) { Opc = X86::FpMOV; } else if (RC == &X86::FR32RegClass || RC == &X86::V4F4RegClass) { - Opc = X86::MOVSSrr; + Opc = X86::MOVAPSrr; } else if (RC == &X86::FR64RegClass || RC == &X86::V2F8RegClass) { - Opc = X86::MOVSDrr; + Opc = X86::MOVAPDrr; } else { assert(0 && "Unknown regclass"); abort();