From 53b59d1d974184657edfd22779e0bb3653d164ec Mon Sep 17 00:00:00 2001 From: Manman Ren Date: Tue, 31 Jul 2012 18:10:39 +0000 Subject: MachineSink: Sort the successors before trying to find SuccToSinkTo. One motivating example is to sink an instruction from a basic block which has two successors: one outside the loop, the other inside the loop. We should try to sink the instruction outside the loop. rdar://11980766 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161062 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/MachineSink.cpp | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) (limited to 'lib/CodeGen/MachineSink.cpp') diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp index 1ce546b578..d02aa6fe60 100644 --- a/lib/CodeGen/MachineSink.cpp +++ b/lib/CodeGen/MachineSink.cpp @@ -99,6 +99,16 @@ namespace { bool PerformTrivialForwardCoalescing(MachineInstr *MI, MachineBasicBlock *MBB); }; + + // SuccessorSorter - Sort Successors according to their loop depth. + struct SuccessorSorter { + SuccessorSorter(MachineLoopInfo *LoopInfo) : LI(LoopInfo) {} + bool operator()(const MachineBasicBlock *LHS, + const MachineBasicBlock *RHS) const { + return LI->getLoopDepth(LHS) < LI->getLoopDepth(RHS); + } + MachineLoopInfo *LI; + }; } // end anonymous namespace char MachineSinking::ID = 0; @@ -526,8 +536,11 @@ MachineBasicBlock *MachineSinking::FindSuccToSinkTo(MachineInstr *MI, // Otherwise, we should look at all the successors and decide which one // we should sink to. - for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(), - E = MBB->succ_end(); SI != E; ++SI) { + // We give successors with smaller loop depth higher priority. + SmallVector Succs(MBB->succ_begin(), MBB->succ_end()); + std::sort(Succs.begin(), Succs.end(), SuccessorSorter(LI)); + for (SmallVector::iterator SI = Succs.begin(), + E = Succs.end(); SI != E; ++SI) { MachineBasicBlock *SuccBlock = *SI; bool LocalUse = false; if (AllUsesDominatedByBlock(Reg, SuccBlock, MBB, -- cgit v1.2.3-70-g09d2