From 1283c6a066eb31b2188c5e6810c3b5f948565d44 Mon Sep 17 00:00:00 2001 From: Evan Cheng Date: Mon, 15 Jun 2009 08:28:29 +0000 Subject: Part 1. - Change register allocation hint to a pair of unsigned integers. The hint type is zero (which means prefer the register specified as second part of the pair) or entirely target dependent. - Allow targets to specify alternative register allocation orders based on allocation hint. Part 2. - Use the register allocation hint system to implement more aggressive load / store multiple formation. - Aggressively form LDRD / STRD. These are formed *before* register allocation. It has to be done this way to shorten live interval of base and offset registers. e.g. v1025 = LDR v1024, 0 v1026 = LDR v1024, 0 => v1025,v1026 = LDRD v1024, 0 If this transformation isn't done before allocation, v1024 will overlap v1025 which means it more difficult to allocate a register pair. - Even with the register allocation hint, it may not be possible to get the desired allocation. In that case, the post-allocation load / store multiple pass must fix the ldrd / strd instructions. They can either become ldm / stm instructions or back to a pair of ldr / str instructions. This is work in progress, not yet enabled. llvm-svn: 73381 --- llvm/lib/CodeGen/LiveInterval.cpp | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) (limited to 'llvm/lib/CodeGen/LiveInterval.cpp') diff --git a/llvm/lib/CodeGen/LiveInterval.cpp b/llvm/lib/CodeGen/LiveInterval.cpp index 97926dd6fd5..4d3ce3a9d43 100644 --- a/llvm/lib/CodeGen/LiveInterval.cpp +++ b/llvm/lib/CodeGen/LiveInterval.cpp @@ -507,12 +507,11 @@ void LiveInterval::join(LiveInterval &Other, const int *LHSValNoAssignments, // Update regalloc hint if currently there isn't one. if (TargetRegisterInfo::isVirtualRegister(reg) && TargetRegisterInfo::isVirtualRegister(Other.reg)) { - std::pair Hint = - MRI->getRegAllocationHint(reg); - if (Hint.first == MachineRegisterInfo::RA_None) { - std::pair OtherHint = + std::pair Hint = MRI->getRegAllocationHint(reg); + if (Hint.first == 0 && Hint.second == 0) { + std::pair OtherHint = MRI->getRegAllocationHint(Other.reg); - if (OtherHint.first != MachineRegisterInfo::RA_None) + if (OtherHint.first || OtherHint.second) MRI->setRegAllocationHint(reg, OtherHint.first, OtherHint.second); } } @@ -772,8 +771,7 @@ void LiveInterval::Copy(const LiveInterval &RHS, BumpPtrAllocator &VNInfoAllocator) { ranges.clear(); valnos.clear(); - std::pair Hint = - MRI->getRegAllocationHint(RHS.reg); + std::pair Hint = MRI->getRegAllocationHint(RHS.reg); MRI->setRegAllocationHint(reg, Hint.first, Hint.second); weight = RHS.weight; -- cgit v1.2.3