From: Sirish Pande Date: Fri, 13 Apr 2012 20:22:19 +0000 (+0000) Subject: Pass to replace tranfer/copy instructions into combine instruction where possible. X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=05a2fea6a51b945bb26cab09bed9295257fad405;p=oota-llvm.git Pass to replace tranfer/copy instructions into combine instruction where possible. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154695 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/lib/Target/Hexagon/CMakeLists.txt b/lib/Target/Hexagon/CMakeLists.txt index 8a49cd8105a..7f4192c0dd9 100644 --- a/lib/Target/Hexagon/CMakeLists.txt +++ b/lib/Target/Hexagon/CMakeLists.txt @@ -29,6 +29,8 @@ add_llvm_target(HexagonCodeGen HexagonTargetMachine.cpp HexagonTargetObjectFile.cpp HexagonVLIWPacketizer.cpp + HexagonNewValueJump.cpp + HexagonCopyToCombine.cpp ) add_subdirectory(TargetInfo) diff --git a/lib/Target/Hexagon/Hexagon.h b/lib/Target/Hexagon/Hexagon.h index 43858b9624f..2738df3717d 100644 --- a/lib/Target/Hexagon/Hexagon.h +++ b/lib/Target/Hexagon/Hexagon.h @@ -40,6 +40,8 @@ namespace llvm { FunctionPass *createHexagonHardwareLoops(); FunctionPass *createHexagonPeephole(); FunctionPass *createHexagonFixupHwLoops(); + FunctionPass *createHexagonNewValueJump(); + FunctionPass *createHexagonCopyToCombine(); FunctionPass *createHexagonPacketizer(); /* TODO: object output. diff --git a/lib/Target/Hexagon/HexagonCopyToCombine.cpp b/lib/Target/Hexagon/HexagonCopyToCombine.cpp new file mode 100644 index 00000000000..90ff5433964 --- /dev/null +++ b/lib/Target/Hexagon/HexagonCopyToCombine.cpp @@ -0,0 +1,473 @@ +//===------- HexagonCopyToCombine.cpp - Hexagon Copy-To-Combine Pass ------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// This pass replaces transfer instructions by combine instructions. +// We walk along a basic block and look for two combinable instructions and try +// to move them together. If we can move them next to each other we do so and +// replace them with a combine instruction. +//===----------------------------------------------------------------------===// +#define DEBUG_TYPE "hexagon-copy-combine" + +#include "llvm/PassSupport.h" +#include "llvm/CodeGen/Passes.h" +#include "llvm/CodeGen/MachineBasicBlock.h" +#include "llvm/CodeGen/MachineFunction.h" +#include "llvm/CodeGen/MachineFunctionPass.h" +#include "llvm/CodeGen/MachineInstr.h" +#include "llvm/CodeGen/MachineInstrBuilder.h" +#include "llvm/Target/TargetRegisterInfo.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" + +#include "Hexagon.h" +#include "HexagonInstrInfo.h" +#include "HexagonRegisterInfo.h" +#include "HexagonSubtarget.h" +#include "HexagonTargetMachine.h" +#include "HexagonMachineFunctionInfo.h" + +using namespace llvm; + +static +cl::opt IsCombinesDisabled("disable-merge-into-combines", + cl::Hidden, cl::ZeroOrMore, + cl::init(false), + cl::desc("Disable merging into combines")); + +namespace { + +class HexagonCopyToCombine : public MachineFunctionPass { + const HexagonInstrInfo *TII; + const TargetRegisterInfo *TRI; +public: + static char ID; + + HexagonCopyToCombine() : MachineFunctionPass(ID) { } + + virtual void getAnalysisUsage(AnalysisUsage &AU) const { + MachineFunctionPass::getAnalysisUsage(AU); + } + + const char *getPassName() const { + return "Hexagon Copy-To-Combine Pass"; + } + + virtual bool runOnMachineFunction(MachineFunction &Fn); + +private: + MachineInstr *findPairable(MachineInstr *I1, bool &DoInsertAtI1); + + void combine(MachineInstr *I1, MachineInstr *I2, + MachineBasicBlock::iterator &MI, bool DoInsertAtI1); + + bool isSafeToMoveTogether(MachineInstr *I1, MachineInstr *I2, + unsigned I1DestReg, unsigned I2DestReg, + bool &DoInsertAtI1); + + void emitCombineRR(MachineBasicBlock::iterator &Before, unsigned DestReg, + MachineOperand &HiOperand, MachineOperand &LoOperand); + + void emitCombineRI(MachineBasicBlock::iterator &Before, unsigned DestReg, + MachineOperand &HiOperand, MachineOperand &LoOperand); + + void emitCombineIR(MachineBasicBlock::iterator &Before, unsigned DestReg, + MachineOperand &HiOperand, MachineOperand &LoOperand); + + void emitCombineII(MachineBasicBlock::iterator &Before, unsigned DestReg, + MachineOperand &HiOperand, MachineOperand &LoOperand); +}; + +} // End anonymous namespace. + +char HexagonCopyToCombine::ID = 0; + +static bool isCombinableInstType(MachineInstr *MI, + const HexagonInstrInfo *TII) { + switch(MI->getOpcode()) { + case Hexagon::TFR: { + // A COPY instruction can be combined if its arguments are IntRegs (32bit). + assert(MI->getOperand(0).isReg() && MI->getOperand(1).isReg()); + + unsigned DestReg = MI->getOperand(0).getReg(); + unsigned SrcReg = MI->getOperand(1).getReg(); + return Hexagon::IntRegsRegClass.contains(DestReg) && + Hexagon::IntRegsRegClass.contains(SrcReg); + } + + case Hexagon::TFRI: { + // A transfer-immediate can be combined if its argument is a signed 8bit + // value. + assert(MI->getOperand(0).isReg() && MI->getOperand(1).isImm()); + unsigned DestReg = MI->getOperand(0).getReg(); + return Hexagon::IntRegsRegClass.contains(DestReg) && + isInt<8>(MI->getOperand(1).getImm()); + } + default: + break; + } + + return false; +} + + +/// areCombinableOperations - Returns true if the two instruction can be merge +/// into a combine (ignoring register constraints). +static bool areCombinableOperations(const TargetRegisterInfo *TRI, + MachineInstr *I1, MachineInstr *I2) { + assert((I1->getOpcode() == Hexagon::TFR || + I1->getOpcode() == Hexagon::TFRI) && + (I2->getOpcode() == Hexagon::TFR || + I2->getOpcode() == Hexagon::TFRI) && + "Assume individual instructions are of a combinable type"); + + const HexagonRegisterInfo *QRI = + static_cast(TRI); + + // V4 added some combine variations (mixed immediate and register source + // operands), if we are on < V4 we can only combine 2 register-to-register + // moves and 2 immediate-to-register moves. + if (QRI->Subtarget.getHexagonArchVersion() < HexagonSubtarget::V4) + return I1->getOpcode() == I2->getOpcode(); + + return true; +} + +static bool isEvenReg(unsigned Reg) { + assert(TargetRegisterInfo::isPhysicalRegister(Reg) && + Hexagon::IntRegsRegClass.contains(Reg)); + return (Reg - Hexagon::R0) % 2 == 0; +} + +static void removeKillInfo(MachineInstr *MI, unsigned RegNotKilled) { + for (unsigned I = 0, E = MI->getNumOperands(); I != E; ++I) { + MachineOperand &Op = MI->getOperand(I); + if (!Op.isReg() || Op.getReg() != RegNotKilled || !Op.isKill()) + continue; + Op.setIsKill(false); + } +} + +/// isUnsafeToMoveAccross - Returns true if it is unsafe to move a copy +/// instruction from \p UseReg to \p DestReg over the instruction \p I. +bool isUnsafeToMoveAccross(MachineInstr *I, unsigned UseReg, unsigned DestReg, + const TargetRegisterInfo *TRI) { + return (UseReg && (I->modifiesRegister(UseReg, TRI))) || + I->modifiesRegister(DestReg, TRI) || + I->readsRegister(DestReg, TRI) || + I->hasUnmodeledSideEffects() || + I->isInlineAsm() || I->isDebugValue(); +} + +/// isSafeToMoveTogether - Returns true if it is safe to move I1 next to I2 such +/// that the two instructions can be paired in a combine. +bool HexagonCopyToCombine::isSafeToMoveTogether(MachineInstr *I1, + MachineInstr *I2, + unsigned I1DestReg, + unsigned I2DestReg, + bool &DoInsertAtI1) { + bool isSafe = true; + + // First try to move I2 towards I1. + { + // A reverse_iterator instantiated like below starts before I2, and I1 + // respectively. + // Look at instructions I in between I2 and (including) I1. + MachineBasicBlock::reverse_iterator I(I2), + End = MachineBasicBlock::reverse_iterator(I1); + bool IsImmUseReg = I2->getOperand(1).isImm(); + unsigned I2UseReg = IsImmUseReg ? 0 : I2->getOperand(1).getReg(); + + // If I2 kills its operand and we move I2 over an instruction that also + // uses I2's use reg we need to modify that (first) instruction to now kill + // this reg. + unsigned KilledOperand = 0; + if (I2->killsRegister(I2UseReg)) + KilledOperand = I2UseReg; + MachineInstr *KillingInstr = 0; + + for (; I != End; ++I) { + // If the intervening instruction I: + // * modifies I2's use reg + // * modifies I2's def reg + // * reads I2's def reg + // * or has unmodelled side effects + // we can't move I2 across it. + if (isUnsafeToMoveAccross(&*I, I2UseReg, I2DestReg, TRI)) { + isSafe = false; + break; + } + + // Update first use of the killed operand. + if (!KillingInstr && KilledOperand && + I->readsRegister(KilledOperand, TRI)) + KillingInstr = &*I; + } + if (isSafe) { + // Update the intermediate instruction to with the kill flag. + if (KillingInstr) { + bool Added = KillingInstr->addRegisterKilled(KilledOperand, TRI, true); + assert(Added && "Must successfully update kill flag"); + removeKillInfo(I2, KilledOperand); + } + DoInsertAtI1 = true; + return true; + } + } + + // Try to move I1 towards I2. + { + // Look at instructions I in between I1 and (including) I2. + MachineBasicBlock::iterator I(I1), + End(next(MachineBasicBlock::iterator(I2))); + bool IsImmUseReg = I1->getOperand(1).isImm(); + unsigned I1UseReg = IsImmUseReg ? 0 : I1->getOperand(1).getReg(); + // Track killed operands. If we move accross an instruction that kills our + // operand, we need to update the kill information on the moved I1. It kills + // the operand now. + MachineInstr *KillingInstr = 0; + unsigned KilledOperand = 0; + + while(++I != End) { + // If the intervening instruction I: + // * modifies I1's use reg + // * modifies I1's def reg + // * reads I1's def reg + // * or has unmodelled side effects + // We introduce this special case because llvm has no api to remove a + // kill flag for a register (a removeRegisterKilled() analogous to + // addRegisterKilled) that handles aliased register correctly. + // * or has a killed aliased register use of I1's use reg + // %D4 = TFRI64 16 + // %R6 = TFR %R9 + // %R8 = KILL %R8, %D4 + // If we want to move R6 = across the KILL instruction we would have + // to remove the %D4 operand. For now, we are + // conservative and disallow the move. + // we can't move I1 across it. + if (isUnsafeToMoveAccross(I, I1UseReg, I1DestReg, TRI) || + // Check for an aliased register kill. Bail out if we see one. + (!I->killsRegister(I1UseReg) && I->killsRegister(I1UseReg, TRI))) + return false; + + // Check for an exact kill (registers match). + if (I1UseReg && I->killsRegister(I1UseReg)) { + assert(KillingInstr == 0 && "Should only see one killing instruction"); + KilledOperand = I1UseReg; + KillingInstr = &*I; + } + } + if (KillingInstr) { + removeKillInfo(KillingInstr, KilledOperand); + // Update I1 to set the kill flag. This flag will later be picked up by + // the new COMBINE instruction. + bool Added = I1->addRegisterKilled(KilledOperand, TRI); + assert(Added && "Must successfully update kill flag"); + } + DoInsertAtI1 = false; + } + + return true; +} + +bool HexagonCopyToCombine::runOnMachineFunction(MachineFunction &MF) { + + if (IsCombinesDisabled) return false; + + bool HasChanged = false; + + // Get target info. + TRI = MF.getTarget().getRegisterInfo(); + TII = static_cast(MF.getTarget().getInstrInfo()); + + // Traverse basic blocks. + for (MachineFunction::iterator BI = MF.begin(), BE = MF.end(); BI != BE; + ++BI) { + // Traverse instructions in basic block. + for(MachineBasicBlock::iterator MI = BI->begin(), End = BI->end(); + MI != End;) { + MachineInstr *I1 = MI++; + + // Ignore instructions that are not combinable. + if (!isCombinableInstType(I1, TII)) + continue; + + // Find a second instruction that can be merged into a combine + // instruction. + bool DoInsertAtI1 = false; + MachineInstr *I2 = findPairable(I1, DoInsertAtI1); + if (I2) { + HasChanged = true; + combine(I1, I2, MI, DoInsertAtI1); + } + } + } + + return HasChanged; +} + +/// findPairable - Returns an instruction that can be merged with \p I1 into a +/// COMBINE instruction or 0 if no such instruction can be found. Returns true +/// in \p DoInsertAtI1 if the combine must be inserted at instruction \p I1 +/// false if the combine must be inserted at the returned instruction. +MachineInstr *HexagonCopyToCombine::findPairable(MachineInstr *I1, + bool &DoInsertAtI1) { + MachineBasicBlock::iterator I2 = next(MachineBasicBlock::iterator(I1)); + unsigned I1DestReg = I1->getOperand(0).getReg(); + + for (MachineBasicBlock::iterator End = I1->getParent()->end(); I2 != End; + ++I2) { + // Bail out early if we see a second definition of I1DestReg. + if (I2->modifiesRegister(I1DestReg, TRI)) + break; + + // Ignore non-combinable instructions. + if (!isCombinableInstType(I2, TII)) + continue; + + unsigned I2DestReg = I2->getOperand(0).getReg(); + + // Check that registers are adjacent and that the first destination register + // is even. + bool IsI1BeforeI2 = (I2DestReg - I1DestReg) == 1; + bool IsI2BeforeI1 = (I1DestReg - I2DestReg) == 1; + unsigned FirstRegIndex = IsI1BeforeI2 ? I1DestReg : I2DestReg; + if ((!IsI1BeforeI2 && !IsI2BeforeI1) || !isEvenReg(FirstRegIndex)) + continue; + + // Check that the two instructions are combinable. V4 allows more + // instructions to be merged into a combine. + if (!areCombinableOperations(TRI, I1, I2)) + break; + + if (isSafeToMoveTogether(I1, I2, I1DestReg, I2DestReg, + DoInsertAtI1)) + return I2; + + // Not safe. Stop searching. + break; + } + return 0; +} + +void HexagonCopyToCombine::combine(MachineInstr *I1, MachineInstr *I2, + MachineBasicBlock::iterator &MI, + bool DoInsertAtI1) { + // We are going to delete I2. If MI points to I2 advance it to the next + // instruction. + if ((MachineInstr *)MI == I2) ++MI; + + // Figure out whether I1 or I2 goes into the lowreg part. + unsigned I1DestReg = I1->getOperand(0).getReg(); + unsigned I2DestReg = I2->getOperand(0).getReg(); + bool IsI1Loreg = (I2DestReg - I1DestReg) == 1; + unsigned LoRegDef = IsI1Loreg ? I1DestReg : I2DestReg; + + // Get the double word register. + unsigned DoubleRegDest = + TRI->getMatchingSuperReg(LoRegDef, Hexagon::subreg_loreg, + Hexagon::DoubleRegsRegisterClass); + assert(DoubleRegDest != 0 && "Expect a valid register"); + + + // Setup source operands. + MachineOperand &LoOperand = IsI1Loreg ? I1->getOperand(1) : + I2->getOperand(1); + MachineOperand &HiOperand = IsI1Loreg ? I2->getOperand(1) : + I1->getOperand(1); + + // Figure out which source is a register and which a constant. + bool IsHiReg = HiOperand.isReg(); + bool IsLoReg = LoOperand.isReg(); + + MachineBasicBlock::iterator InsertPt(DoInsertAtI1 ? I1 : I2); + // Emit combine. + if (IsHiReg && IsLoReg) + emitCombineRR(InsertPt, DoubleRegDest, HiOperand, LoOperand); + else if (IsHiReg) + emitCombineRI(InsertPt, DoubleRegDest, HiOperand, LoOperand); + else if (IsLoReg) + emitCombineIR(InsertPt, DoubleRegDest, HiOperand, LoOperand); + else + emitCombineII(InsertPt, DoubleRegDest, HiOperand, LoOperand); + + I1->eraseFromParent(); + I2->eraseFromParent(); +} + +void HexagonCopyToCombine::emitCombineII(MachineBasicBlock::iterator &InsertPt, + unsigned DoubleDestReg, + MachineOperand &HiOperand, + MachineOperand &LoOperand) { + DebugLoc DL = InsertPt->getDebugLoc(); + MachineBasicBlock *BB = InsertPt->getParent(); + + // Insert new combine instruction. + // DoubleRegDest = combine #HiImm, #LoImm + BuildMI(*BB, InsertPt, DL, TII->get(Hexagon::COMBINE_ii), DoubleDestReg) + .addImm(HiOperand.getImm()) + .addImm(LoOperand.getImm()); +} + +void HexagonCopyToCombine::emitCombineIR(MachineBasicBlock::iterator &InsertPt, + unsigned DoubleDestReg, + MachineOperand &HiOperand, + MachineOperand &LoOperand) { + unsigned LoReg = LoOperand.getReg(); + unsigned LoRegKillFlag = getKillRegState(LoOperand.isKill()); + + DebugLoc DL = InsertPt->getDebugLoc(); + MachineBasicBlock *BB = InsertPt->getParent(); + + // Insert new combine instruction. + // DoubleRegDest = combine #HiImm, LoReg + BuildMI(*BB, InsertPt, DL, TII->get(Hexagon::COMBINE_ir_V4), DoubleDestReg) + .addImm(HiOperand.getImm()) + .addReg(LoReg, LoRegKillFlag); +} + +void HexagonCopyToCombine::emitCombineRI(MachineBasicBlock::iterator &InsertPt, + unsigned DoubleDestReg, + MachineOperand &HiOperand, + MachineOperand &LoOperand) { + unsigned HiRegKillFlag = getKillRegState(HiOperand.isKill()); + unsigned HiReg = HiOperand.getReg(); + + DebugLoc DL = InsertPt->getDebugLoc(); + MachineBasicBlock *BB = InsertPt->getParent(); + + // Insert new combine instruction. + // DoubleRegDest = combine HiReg, #LoImm + BuildMI(*BB, InsertPt, DL, TII->get(Hexagon::COMBINE_ri_V4), DoubleDestReg) + .addReg(HiReg, HiRegKillFlag) + .addImm(LoOperand.getImm()); +} + +void HexagonCopyToCombine::emitCombineRR(MachineBasicBlock::iterator &InsertPt, + unsigned DoubleDestReg, + MachineOperand &HiOperand, + MachineOperand &LoOperand) { + unsigned LoRegKillFlag = getKillRegState(LoOperand.isKill()); + unsigned HiRegKillFlag = getKillRegState(HiOperand.isKill()); + unsigned LoReg = LoOperand.getReg(); + unsigned HiReg = HiOperand.getReg(); + + DebugLoc DL = InsertPt->getDebugLoc(); + MachineBasicBlock *BB = InsertPt->getParent(); + + // Insert new combine instruction. + // DoubleRegDest = combine HiReg, LoReg + BuildMI(*BB, InsertPt, DL, TII->get(Hexagon::COMBINE_rr), DoubleDestReg) + .addReg(HiReg, HiRegKillFlag) + .addReg(LoReg, LoRegKillFlag); +} + +FunctionPass *llvm::createHexagonCopyToCombine() { + return new HexagonCopyToCombine(); +} + diff --git a/lib/Target/Hexagon/HexagonInstrInfo.td b/lib/Target/Hexagon/HexagonInstrInfo.td index fd5adef0f63..cf7222a0be1 100644 --- a/lib/Target/Hexagon/HexagonInstrInfo.td +++ b/lib/Target/Hexagon/HexagonInstrInfo.td @@ -246,6 +246,12 @@ def COMBINE_rr : ALU32_rr<(outs DoubleRegs:$dst), "$dst = combine($src1, $src2)", []>; +let neverHasSideEffects = 1 in +def COMBINE_ii : ALU32_ii<(outs DoubleRegs:$dst), + (ins s8Imm:$src1, s8Imm:$src2), + "$dst = combine(#$src1, #$src2)", + []>; + // Mux. def VMUX_prr64 : ALU64_rr<(outs DoubleRegs:$dst), (ins PredRegs:$src1, DoubleRegs:$src2, diff --git a/lib/Target/Hexagon/HexagonTargetMachine.cpp b/lib/Target/Hexagon/HexagonTargetMachine.cpp index 411325bf963..34036b2d104 100644 --- a/lib/Target/Hexagon/HexagonTargetMachine.cpp +++ b/lib/Target/Hexagon/HexagonTargetMachine.cpp @@ -122,6 +122,7 @@ bool HexagonPassConfig::addPostRegAlloc() { bool HexagonPassConfig::addPreSched2() { + PM.add(createHexagonCopyToCombine()); addPass(IfConverterID); return true; }