From 178ae081fb6c1cf8393e80755dac941defbfc6a4 Mon Sep 17 00:00:00 2001 From: Quentin Colombet Date: Wed, 8 Jun 2016 01:17:10 +0000 Subject: [PATCH] [RegisterBankInfo] Adapt the copy cost logic to give something sane by default. The generic implementation stated that all copies were free, which is unlikely. Now, only the copies within the same register bank are free. We assume they will get coalesced. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@272085 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h b/include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h index cc2c80d186c..e9b2a069a53 100644 --- a/include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h +++ b/include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h @@ -359,7 +359,11 @@ public: /// \note Since this is a copy, both registers have the same size. virtual unsigned copyCost(const RegisterBank &A, const RegisterBank &B, unsigned Size) const { - return 0; + // Optimistically assume that copies are coalesced. I.e., when + // they are on the same bank, they are free. + // Otherwise assume a non-zero cost of 1. The targets are supposed + // to override that properly anyway if they care. + return &A != &B; } /// Identifier used when the related instruction mapping instance -- 2.11.0