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1ac2927c37
This patch removes the PBQPBuilder class and its subclasses and replaces them with a composable constraints class: PBQPRAConstraint. This allows constraints that are only required for optimisation (e.g. coalescing, soft pairing) to be mixed and matched. This patch also introduces support for target writers to supply custom constraints for their targets by overriding a TargetSubtargetInfo method: std::unique_ptr<PBQPRAConstraints> getCustomPBQPConstraints() const; This patch should have no effect on allocations. llvm-svn: 219421
385 lines
12 KiB
C++
385 lines
12 KiB
C++
//===-- AArch64PBQPRegAlloc.cpp - AArch64 specific PBQP constraints -------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// This file contains the AArch64 / Cortex-A57 specific register allocation
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// constraints for use by the PBQP register allocator.
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//
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// It is essentially a transcription of what is contained in
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// AArch64A57FPLoadBalancing, which tries to use a balanced
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// mix of odd and even D-registers when performing a critical sequence of
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// independent, non-quadword FP/ASIMD floating-point multiply-accumulates.
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "aarch64-pbqp"
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#include "AArch64.h"
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#include "AArch64PBQPRegAlloc.h"
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#include "AArch64RegisterInfo.h"
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#include "llvm/CodeGen/LiveIntervalAnalysis.h"
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#include "llvm/CodeGen/MachineBasicBlock.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/RegAllocPBQP.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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namespace {
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#ifndef NDEBUG
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bool isFPReg(unsigned reg) {
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return AArch64::FPR32RegClass.contains(reg) ||
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AArch64::FPR64RegClass.contains(reg) ||
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AArch64::FPR128RegClass.contains(reg);
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}
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#endif
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bool isOdd(unsigned reg) {
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switch (reg) {
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default:
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llvm_unreachable("Register is not from the expected class !");
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case AArch64::S1:
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case AArch64::S3:
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case AArch64::S5:
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case AArch64::S7:
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case AArch64::S9:
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case AArch64::S11:
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case AArch64::S13:
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case AArch64::S15:
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case AArch64::S17:
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case AArch64::S19:
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case AArch64::S21:
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case AArch64::S23:
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case AArch64::S25:
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case AArch64::S27:
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case AArch64::S29:
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case AArch64::S31:
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case AArch64::D1:
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case AArch64::D3:
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case AArch64::D5:
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case AArch64::D7:
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case AArch64::D9:
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case AArch64::D11:
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case AArch64::D13:
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case AArch64::D15:
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case AArch64::D17:
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case AArch64::D19:
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case AArch64::D21:
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case AArch64::D23:
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case AArch64::D25:
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case AArch64::D27:
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case AArch64::D29:
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case AArch64::D31:
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case AArch64::Q1:
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case AArch64::Q3:
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case AArch64::Q5:
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case AArch64::Q7:
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case AArch64::Q9:
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case AArch64::Q11:
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case AArch64::Q13:
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case AArch64::Q15:
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case AArch64::Q17:
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case AArch64::Q19:
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case AArch64::Q21:
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case AArch64::Q23:
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case AArch64::Q25:
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case AArch64::Q27:
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case AArch64::Q29:
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case AArch64::Q31:
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return true;
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case AArch64::S0:
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case AArch64::S2:
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case AArch64::S4:
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case AArch64::S6:
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case AArch64::S8:
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case AArch64::S10:
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case AArch64::S12:
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case AArch64::S14:
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case AArch64::S16:
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case AArch64::S18:
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case AArch64::S20:
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case AArch64::S22:
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case AArch64::S24:
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case AArch64::S26:
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case AArch64::S28:
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case AArch64::S30:
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case AArch64::D0:
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case AArch64::D2:
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case AArch64::D4:
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case AArch64::D6:
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case AArch64::D8:
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case AArch64::D10:
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case AArch64::D12:
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case AArch64::D14:
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case AArch64::D16:
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case AArch64::D18:
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case AArch64::D20:
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case AArch64::D22:
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case AArch64::D24:
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case AArch64::D26:
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case AArch64::D28:
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case AArch64::D30:
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case AArch64::Q0:
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case AArch64::Q2:
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case AArch64::Q4:
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case AArch64::Q6:
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case AArch64::Q8:
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case AArch64::Q10:
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case AArch64::Q12:
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case AArch64::Q14:
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case AArch64::Q16:
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case AArch64::Q18:
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case AArch64::Q20:
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case AArch64::Q22:
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case AArch64::Q24:
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case AArch64::Q26:
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case AArch64::Q28:
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case AArch64::Q30:
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return false;
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}
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}
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bool haveSameParity(unsigned reg1, unsigned reg2) {
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assert(isFPReg(reg1) && "Expecting an FP register for reg1");
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assert(isFPReg(reg2) && "Expecting an FP register for reg2");
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return isOdd(reg1) == isOdd(reg2);
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}
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}
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bool A57PBQPConstraints::addIntraChainConstraint(PBQPRAGraph &G, unsigned Rd,
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unsigned Ra) {
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if (Rd == Ra)
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return false;
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const TargetRegisterInfo &TRI =
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*G.getMetadata().MF.getTarget().getSubtargetImpl()->getRegisterInfo();
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LiveIntervals &LIs = G.getMetadata().LIS;
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if (TRI.isPhysicalRegister(Rd) || TRI.isPhysicalRegister(Ra)) {
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DEBUG(dbgs() << "Rd is a physical reg:" << TRI.isPhysicalRegister(Rd)
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<< '\n');
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DEBUG(dbgs() << "Ra is a physical reg:" << TRI.isPhysicalRegister(Ra)
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<< '\n');
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return false;
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}
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PBQPRAGraph::NodeId node1 = G.getMetadata().getNodeIdForVReg(Rd);
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PBQPRAGraph::NodeId node2 = G.getMetadata().getNodeIdForVReg(Ra);
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const PBQPRAGraph::NodeMetadata::OptionToRegMap *vRdAllowed =
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&G.getNodeMetadata(node1).getOptionRegs();
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const PBQPRAGraph::NodeMetadata::OptionToRegMap *vRaAllowed =
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&G.getNodeMetadata(node2).getOptionRegs();
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PBQPRAGraph::EdgeId edge = G.findEdge(node1, node2);
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// The edge does not exist. Create one with the appropriate interference
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// costs.
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if (edge == G.invalidEdgeId()) {
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const LiveInterval &ld = LIs.getInterval(Rd);
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const LiveInterval &la = LIs.getInterval(Ra);
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bool livesOverlap = ld.overlaps(la);
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PBQPRAGraph::RawMatrix costs(vRdAllowed->size() + 1,
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vRaAllowed->size() + 1, 0);
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for (unsigned i = 0, ie = vRdAllowed->size(); i != ie; ++i) {
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unsigned pRd = (*vRdAllowed)[i];
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for (unsigned j = 0, je = vRaAllowed->size(); j != je; ++j) {
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unsigned pRa = (*vRaAllowed)[j];
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if (livesOverlap && TRI.regsOverlap(pRd, pRa))
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costs[i + 1][j + 1] = std::numeric_limits<PBQP::PBQPNum>::infinity();
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else
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costs[i + 1][j + 1] = haveSameParity(pRd, pRa) ? 0.0 : 1.0;
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}
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}
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G.addEdge(node1, node2, std::move(costs));
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return true;
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}
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if (G.getEdgeNode1Id(edge) == node2) {
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std::swap(node1, node2);
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std::swap(vRdAllowed, vRaAllowed);
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}
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// Enforce minCost(sameParity(RaClass)) > maxCost(otherParity(RdClass))
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PBQPRAGraph::RawMatrix costs(G.getEdgeCosts(edge));
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for (unsigned i = 0, ie = vRdAllowed->size(); i != ie; ++i) {
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unsigned pRd = (*vRdAllowed)[i];
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// Get the maximum cost (excluding unallocatable reg) for same parity
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// registers
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PBQP::PBQPNum sameParityMax = std::numeric_limits<PBQP::PBQPNum>::min();
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for (unsigned j = 0, je = vRaAllowed->size(); j != je; ++j) {
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unsigned pRa = (*vRaAllowed)[j];
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if (haveSameParity(pRd, pRa))
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if (costs[i + 1][j + 1] !=
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std::numeric_limits<PBQP::PBQPNum>::infinity() &&
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costs[i + 1][j + 1] > sameParityMax)
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sameParityMax = costs[i + 1][j + 1];
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}
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// Ensure all registers with a different parity have a higher cost
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// than sameParityMax
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for (unsigned j = 0, je = vRaAllowed->size(); j != je; ++j) {
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unsigned pRa = (*vRaAllowed)[j];
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if (!haveSameParity(pRd, pRa))
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if (sameParityMax > costs[i + 1][j + 1])
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costs[i + 1][j + 1] = sameParityMax + 1.0;
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}
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}
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G.setEdgeCosts(edge, std::move(costs));
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return true;
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}
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void A57PBQPConstraints::addInterChainConstraint(PBQPRAGraph &G, unsigned Rd,
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unsigned Ra) {
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const TargetRegisterInfo &TRI =
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*G.getMetadata().MF.getTarget().getSubtargetImpl()->getRegisterInfo();
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(void)TRI;
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LiveIntervals &LIs = G.getMetadata().LIS;
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// Do some Chain management
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if (Chains.count(Ra)) {
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if (Rd != Ra) {
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DEBUG(dbgs() << "Moving acc chain from " << PrintReg(Ra, &TRI) << " to "
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<< PrintReg(Rd, &TRI) << '\n';);
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Chains.remove(Ra);
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Chains.insert(Rd);
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}
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} else {
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DEBUG(dbgs() << "Creating new acc chain for " << PrintReg(Rd, &TRI)
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<< '\n';);
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Chains.insert(Rd);
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}
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PBQPRAGraph::NodeId node1 = G.getMetadata().getNodeIdForVReg(Rd);
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const LiveInterval &ld = LIs.getInterval(Rd);
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for (auto r : Chains) {
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// Skip self
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if (r == Rd)
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continue;
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const LiveInterval &lr = LIs.getInterval(r);
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if (ld.overlaps(lr)) {
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const PBQPRAGraph::NodeMetadata::OptionToRegMap *vRdAllowed =
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&G.getNodeMetadata(node1).getOptionRegs();
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PBQPRAGraph::NodeId node2 = G.getMetadata().getNodeIdForVReg(r);
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const PBQPRAGraph::NodeMetadata::OptionToRegMap *vRrAllowed =
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&G.getNodeMetadata(node2).getOptionRegs();
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PBQPRAGraph::EdgeId edge = G.findEdge(node1, node2);
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assert(edge != G.invalidEdgeId() &&
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"PBQP error ! The edge should exist !");
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DEBUG(dbgs() << "Refining constraint !\n";);
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if (G.getEdgeNode1Id(edge) == node2) {
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std::swap(node1, node2);
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std::swap(vRdAllowed, vRrAllowed);
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}
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// Enforce that cost is higher with all other Chains of the same parity
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PBQP::Matrix costs(G.getEdgeCosts(edge));
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for (unsigned i = 0, ie = vRdAllowed->size(); i != ie; ++i) {
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unsigned pRd = (*vRdAllowed)[i];
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// Get the maximum cost (excluding unallocatable reg) for all other
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// parity registers
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PBQP::PBQPNum sameParityMax = std::numeric_limits<PBQP::PBQPNum>::min();
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for (unsigned j = 0, je = vRrAllowed->size(); j != je; ++j) {
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unsigned pRa = (*vRrAllowed)[j];
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if (!haveSameParity(pRd, pRa))
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if (costs[i + 1][j + 1] !=
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std::numeric_limits<PBQP::PBQPNum>::infinity() &&
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costs[i + 1][j + 1] > sameParityMax)
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sameParityMax = costs[i + 1][j + 1];
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}
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// Ensure all registers with same parity have a higher cost
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// than sameParityMax
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for (unsigned j = 0, je = vRrAllowed->size(); j != je; ++j) {
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unsigned pRa = (*vRrAllowed)[j];
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if (haveSameParity(pRd, pRa))
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if (sameParityMax > costs[i + 1][j + 1])
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costs[i + 1][j + 1] = sameParityMax + 1.0;
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}
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}
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G.setEdgeCosts(edge, std::move(costs));
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}
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}
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}
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void A57PBQPConstraints::apply(PBQPRAGraph &G) {
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MachineFunction &MF = G.getMetadata().MF;
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const TargetRegisterInfo &TRI =
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*MF.getTarget().getSubtargetImpl()->getRegisterInfo();
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(void)TRI;
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DEBUG(MF.dump());
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for (MachineFunction::const_iterator mbbItr = MF.begin(), mbbEnd = MF.end();
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mbbItr != mbbEnd; ++mbbItr) {
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const MachineBasicBlock *MBB = &*mbbItr;
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Chains.clear(); // FIXME: really needed ? Could not work at MF level ?
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for (MachineBasicBlock::const_iterator miItr = MBB->begin(),
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miEnd = MBB->end();
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miItr != miEnd; ++miItr) {
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const MachineInstr *MI = &*miItr;
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switch (MI->getOpcode()) {
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case AArch64::FMSUBSrrr:
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case AArch64::FMADDSrrr:
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case AArch64::FNMSUBSrrr:
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case AArch64::FNMADDSrrr:
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case AArch64::FMSUBDrrr:
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case AArch64::FMADDDrrr:
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case AArch64::FNMSUBDrrr:
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case AArch64::FNMADDDrrr: {
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unsigned Rd = MI->getOperand(0).getReg();
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unsigned Ra = MI->getOperand(3).getReg();
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if (addIntraChainConstraint(G, Rd, Ra))
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addInterChainConstraint(G, Rd, Ra);
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break;
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}
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case AArch64::FMLAv2f32:
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case AArch64::FMLSv2f32: {
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unsigned Rd = MI->getOperand(0).getReg();
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addInterChainConstraint(G, Rd, Rd);
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break;
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}
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default:
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// Forget Chains which have been killed
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for (auto r : Chains) {
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SmallVector<unsigned, 8> toDel;
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if (MI->killsRegister(r)) {
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DEBUG(dbgs() << "Killing chain " << PrintReg(r, &TRI) << " at ";
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MI->print(dbgs()););
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toDel.push_back(r);
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}
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while (!toDel.empty()) {
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Chains.remove(toDel.back());
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toDel.pop_back();
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}
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}
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}
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}
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}
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}
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