From 612b85e58c1ba7150135d6046cb02d33a239fcd6 Mon Sep 17 00:00:00 2001 From: Kalle Raiskila Date: Mon, 28 Feb 2011 14:08:24 +0000 Subject: [PATCH] Add branch hinting for SPU. The implemented algorithm is overly simplistic (just speculate all branches are taken)- this is work in progress. llvm-svn: 126651 --- llvm/lib/Target/CellSPU/SPUAsmPrinter.cpp | 7 +++ llvm/lib/Target/CellSPU/SPUInstrFormats.td | 22 ++++++++ llvm/lib/Target/CellSPU/SPUInstrInfo.cpp | 64 +++++++++++++++++++++- llvm/lib/Target/CellSPU/SPUInstrInfo.td | 6 +- 4 files changed, 94 insertions(+), 5 deletions(-) diff --git a/llvm/lib/Target/CellSPU/SPUAsmPrinter.cpp b/llvm/lib/Target/CellSPU/SPUAsmPrinter.cpp index 40404614b703..fd96694b32fe 100644 --- a/llvm/lib/Target/CellSPU/SPUAsmPrinter.cpp +++ b/llvm/lib/Target/CellSPU/SPUAsmPrinter.cpp @@ -182,6 +182,10 @@ namespace { printOp(MI->getOperand(OpNo), O); } + void printHBROperand(const MachineInstr *MI, unsigned OpNo, raw_ostream &O) { + printOp(MI->getOperand(OpNo), O); + } + void printPCRelativeOperand(const MachineInstr *MI, unsigned OpNo, raw_ostream &O) { // Used to generate a ".-", but it turns out that the assembler // really wants the target. @@ -279,6 +283,9 @@ void SPUAsmPrinter::printOp(const MachineOperand &MO, raw_ostream &O) { } O << *Mang->getSymbol(MO.getGlobal()); return; + case MachineOperand::MO_MCSymbol: + O << *(MO.getMCSymbol()); + return; default: O << ""; return; diff --git a/llvm/lib/Target/CellSPU/SPUInstrFormats.td b/llvm/lib/Target/CellSPU/SPUInstrFormats.td index 21bc275209c6..bdbe2552dcdd 100644 --- a/llvm/lib/Target/CellSPU/SPUInstrFormats.td +++ b/llvm/lib/Target/CellSPU/SPUInstrFormats.td @@ -296,3 +296,25 @@ class Pseudo pattern> let Pattern = pattern; let Inst{31-0} = 0; } + +//===----------------------------------------------------------------------===// +// Branch hint formats +//===----------------------------------------------------------------------===// +// For hbrr and hbra +class HBI16Form opcode, dag IOL, string asmstr> + : Instruction { + field bits<32> Inst; + bits<16>i16; + bits<9>RO; + + let Namespace = "SPU"; + let InOperandList = IOL; + let OutOperandList = (outs); //no output + let AsmString = asmstr; + let Itinerary = BranchHints; + + let Inst{0-6} = opcode; + let Inst{7-8} = RO{8-7}; + let Inst{9-24} = i16; + let Inst{25-31} = RO{6-0}; +} diff --git a/llvm/lib/Target/CellSPU/SPUInstrInfo.cpp b/llvm/lib/Target/CellSPU/SPUInstrInfo.cpp index f9e6c72ef310..080434d66789 100644 --- a/llvm/lib/Target/CellSPU/SPUInstrInfo.cpp +++ b/llvm/lib/Target/CellSPU/SPUInstrInfo.cpp @@ -21,6 +21,7 @@ #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/raw_ostream.h" +#include "llvm/MC/MCContext.h" using namespace llvm; @@ -281,9 +282,20 @@ SPUInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB, return true; } +// search MBB for branch hint labels and branch hit ops +static void removeHBR( MachineBasicBlock &MBB) { + for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I){ + if (I->getOpcode() == SPU::HBRA || + I->getOpcode() == SPU::HBR_LABEL){ + I=MBB.erase(I); + } + } +} + unsigned SPUInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const { MachineBasicBlock::iterator I = MBB.end(); + removeHBR(MBB); if (I == MBB.begin()) return 0; --I; @@ -314,6 +326,23 @@ SPUInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const { return 2; } +/** Find the optimal position for a hint branch instruction in a basic block. + * This should take into account: + * -the branch hint delays + * -congestion of the memory bus + * -dual-issue scheduling (i.e. avoid insertion of nops) + * Current implementation is rather simplistic. + */ +static MachineBasicBlock::iterator findHBRPosition(MachineBasicBlock &MBB) +{ + MachineBasicBlock::iterator J = MBB.end(); + for( int i=0; i<8; i++) { + if( J == MBB.begin() ) return J; + J--; + } + return J; +} + unsigned SPUInstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB, MachineBasicBlock *FBB, @@ -324,32 +353,61 @@ SPUInstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB, assert((Cond.size() == 2 || Cond.size() == 0) && "SPU branch conditions have two components!"); + MachineInstrBuilder MIB; + //TODO: make a more accurate algorithm. + bool haveHBR = MBB.size()>8; + + removeHBR(MBB); + MCSymbol *branchLabel = MBB.getParent()->getContext().CreateTempSymbol(); + // Add a label just before the branch + if (haveHBR) + MIB = BuildMI(&MBB, DL, get(SPU::HBR_LABEL)).addSym(branchLabel); + // One-way branch. if (FBB == 0) { if (Cond.empty()) { // Unconditional branch - MachineInstrBuilder MIB = BuildMI(&MBB, DL, get(SPU::BR)); + MIB = BuildMI(&MBB, DL, get(SPU::BR)); MIB.addMBB(TBB); DEBUG(errs() << "Inserted one-way uncond branch: "); DEBUG((*MIB).dump()); + + // basic blocks have just one branch so it is safe to add the hint a its + if (haveHBR) { + MIB = BuildMI( MBB, findHBRPosition(MBB), DL, get(SPU::HBRA)); + MIB.addSym(branchLabel); + MIB.addMBB(TBB); + } } else { // Conditional branch - MachineInstrBuilder MIB = BuildMI(&MBB, DL, get(Cond[0].getImm())); + MIB = BuildMI(&MBB, DL, get(Cond[0].getImm())); MIB.addReg(Cond[1].getReg()).addMBB(TBB); + if (haveHBR) { + MIB = BuildMI(MBB, findHBRPosition(MBB), DL, get(SPU::HBRA)); + MIB.addSym(branchLabel); + MIB.addMBB(TBB); + } + DEBUG(errs() << "Inserted one-way cond branch: "); DEBUG((*MIB).dump()); } return 1; } else { - MachineInstrBuilder MIB = BuildMI(&MBB, DL, get(Cond[0].getImm())); + MIB = BuildMI(&MBB, DL, get(Cond[0].getImm())); MachineInstrBuilder MIB2 = BuildMI(&MBB, DL, get(SPU::BR)); // Two-way Conditional Branch. MIB.addReg(Cond[1].getReg()).addMBB(TBB); MIB2.addMBB(FBB); + if (haveHBR) { + MIB = BuildMI( MBB, findHBRPosition(MBB), DL, get(SPU::HBRA)); + MIB.addSym(branchLabel); + MIB.addMBB(FBB); + } + DEBUG(errs() << "Inserted conditional branch: "); DEBUG((*MIB).dump()); DEBUG(errs() << "part 2: "); diff --git a/llvm/lib/Target/CellSPU/SPUInstrInfo.td b/llvm/lib/Target/CellSPU/SPUInstrInfo.td index 25f6fd000b8b..02f52b369532 100644 --- a/llvm/lib/Target/CellSPU/SPUInstrInfo.td +++ b/llvm/lib/Target/CellSPU/SPUInstrInfo.td @@ -28,6 +28,8 @@ let hasCtrlDep = 1, Defs = [R1], Uses = [R1] in { def ADJCALLSTACKUP : Pseudo<(outs), (ins u16imm_i32:$amt), "${:comment} ADJCALLSTACKUP", [(callseq_end timm:$amt)]>; + def HBR_LABEL : Pseudo<(outs), (ins hbrtarget:$targ), + "$targ:\t${:comment}branch hint target",[ ]>; } //===----------------------------------------------------------------------===// @@ -4208,8 +4210,8 @@ def : Pat<(fabs (v4f32 VECREG:$rA)), //===----------------------------------------------------------------------===// // Hint for branch instructions: //===----------------------------------------------------------------------===// - -/* def HBR : SPUInstr<(outs), (ins), "hbr\t" */ +def HBRA : + HBI16Form<0b0001001,(ins hbrtarget:$brinst, brtarget:$btarg), "hbra\t$brinst, $btarg">; //===----------------------------------------------------------------------===// // Execution, Load NOP (execute NOPs belong in even pipeline, load NOPs belong