From 9df3605dea17e84f8183581f6103bd0c79e2a606 Mon Sep 17 00:00:00 2001 From: Dimitry Andric Date: Sat, 1 Jul 2017 13:22:02 +0000 Subject: Vendor import of llvm trunk r306956: https://llvm.org/svn/llvm-project/llvm/trunk@306956 --- lib/CodeGen/TwoAddressInstructionPass.cpp | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'lib/CodeGen/TwoAddressInstructionPass.cpp') diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp index 552a89f76ca2..83c00e24d14f 100644 --- a/lib/CodeGen/TwoAddressInstructionPass.cpp +++ b/lib/CodeGen/TwoAddressInstructionPass.cpp @@ -68,6 +68,13 @@ EnableRescheduling("twoaddr-reschedule", cl::desc("Coalesce copies by rescheduling (default=true)"), cl::init(true), cl::Hidden); +// Limit the number of dataflow edges to traverse when evaluating the benefit +// of commuting operands. +static cl::opt MaxDataFlowEdge( + "dataflow-edge-limit", cl::Hidden, cl::init(3), + cl::desc("Maximum number of dataflow edges to traverse when evaluating " + "the benefit of commuting operands")); + namespace { class TwoAddressInstructionPass : public MachineFunctionPass { MachineFunction *MF; @@ -637,10 +644,10 @@ isProfitableToCommute(unsigned regA, unsigned regB, unsigned regC, // To more generally minimize register copies, ideally the logic of two addr // instruction pass should be integrated with register allocation pass where // interference graph is available. - if (isRevCopyChain(regC, regA, 3)) + if (isRevCopyChain(regC, regA, MaxDataFlowEdge)) return true; - if (isRevCopyChain(regB, regA, 3)) + if (isRevCopyChain(regB, regA, MaxDataFlowEdge)) return false; // Since there are no intervening uses for both registers, then commute -- cgit v1.3