diff options
Diffstat (limited to 'lib/Target/PowerPC/PPCBranchSelector.cpp')
| -rw-r--r-- | lib/Target/PowerPC/PPCBranchSelector.cpp | 220 |
1 files changed, 115 insertions, 105 deletions
diff --git a/lib/Target/PowerPC/PPCBranchSelector.cpp b/lib/Target/PowerPC/PPCBranchSelector.cpp index 7bd0afe..e7fce56 100644 --- a/lib/Target/PowerPC/PPCBranchSelector.cpp +++ b/lib/Target/PowerPC/PPCBranchSelector.cpp @@ -15,121 +15,19 @@ // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "bsel" #include "PPC.h" #include "PPCInstrBuilder.h" #include "PPCInstrInfo.h" #include "llvm/CodeGen/MachineFunctionPass.h" -#include "llvm/Support/Debug.h" #include <map> using namespace llvm; namespace { - struct BSel : public MachineFunctionPass { + struct PPCBSel : public MachineFunctionPass { // OffsetMap - Mapping between BB and byte offset from start of function std::map<MachineBasicBlock*, unsigned> OffsetMap; - /// bytesForOpcode - A convenience function for totalling up the number of - /// bytes in a basic block. - /// - static unsigned bytesForOpcode(unsigned opcode) { - switch (opcode) { - case PPC::COND_BRANCH: - // while this will be 4 most of the time, if we emit 12 it is just a - // minor pessimization that saves us from having to worry about - // keeping the offsets up to date later when we emit long branch glue. - return 12; - case PPC::IMPLICIT_DEF_GPR: // no asm emitted - case PPC::IMPLICIT_DEF_F4: // no asm emitted - case PPC::IMPLICIT_DEF_F8: // no asm emitted - return 0; - default: - break; - } - return 4; // PowerPC instructions are all 4 bytes - } - - virtual bool runOnMachineFunction(MachineFunction &Fn) { - // Running total of instructions encountered since beginning of function - unsigned ByteCount = 0; - - // For each MBB, add its offset to the offset map, and count up its - // instructions - for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E; - ++MFI) { - MachineBasicBlock *MBB = MFI; - OffsetMap[MBB] = ByteCount; - - for (MachineBasicBlock::iterator MBBI = MBB->begin(), EE = MBB->end(); - MBBI != EE; ++MBBI) - ByteCount += bytesForOpcode(MBBI->getOpcode()); - } - - // We're about to run over the MBB's again, so reset the ByteCount - ByteCount = 0; - - // For each MBB, find the conditional branch pseudo instructions, and - // calculate the difference between the target MBB and the current ICount - // to decide whether or not to emit a short or long branch. - // - // short branch: - // bCC .L_TARGET_MBB - // - // long branch: - // bInverseCC $PC+8 - // b .L_TARGET_MBB - // b .L_FALLTHROUGH_MBB - - for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E; - ++MFI) { - MachineBasicBlock *MBB = MFI; - - for (MachineBasicBlock::iterator MBBI = MBB->begin(), EE = MBB->end(); - MBBI != EE; ++MBBI) { - // We may end up deleting the MachineInstr that MBBI points to, so - // remember its opcode now so we can refer to it after calling erase() - unsigned OpcodeToReplace = MBBI->getOpcode(); - - if (OpcodeToReplace == PPC::COND_BRANCH) { - MachineBasicBlock::iterator MBBJ = MBBI; - ++MBBJ; - - // condbranch operands: - // 0. CR0 register - // 1. bc opcode - // 2. target MBB - // 3. fallthrough MBB - MachineBasicBlock *trueMBB = - MBBI->getOperand(2).getMachineBasicBlock(); - MachineBasicBlock *falseMBB = - MBBI->getOperand(3).getMachineBasicBlock(); - - int Displacement = OffsetMap[trueMBB] - ByteCount; - unsigned Opcode = MBBI->getOperand(1).getImmedValue(); - unsigned CRReg = MBBI->getOperand(0).getReg(); - unsigned Inverted = PPCInstrInfo::invertPPCBranchOpcode(Opcode); - - if (Displacement >= -32768 && Displacement <= 32767) { - BuildMI(*MBB, MBBJ, Opcode, 2).addReg(CRReg).addMBB(trueMBB); - } else { - BuildMI(*MBB, MBBJ, Inverted, 2).addReg(CRReg).addSImm(8); - BuildMI(*MBB, MBBJ, PPC::B, 1).addMBB(trueMBB); - BuildMI(*MBB, MBBJ, PPC::B, 1).addMBB(falseMBB); - } - - // Erase the psuedo COND_BRANCH instruction, and then back up the - // iterator so that when the for loop increments it, we end up in - // the correct place rather than iterating off the end. - MBB->erase(MBBI); - MBBI = --MBBJ; - } - ByteCount += bytesForOpcode(OpcodeToReplace); - } - } - - OffsetMap.clear(); - return true; - } + virtual bool runOnMachineFunction(MachineFunction &Fn); virtual const char *getPassName() const { return "PowerPC Branch Selection"; @@ -141,5 +39,117 @@ namespace { /// Pass /// FunctionPass *llvm::createPPCBranchSelectionPass() { - return new BSel(); + return new PPCBSel(); +} + +/// getNumBytesForInstruction - Return the number of bytes of code the specified +/// instruction may be. This returns the maximum number of bytes. +/// +static unsigned getNumBytesForInstruction(MachineInstr *MI) { + switch (MI->getOpcode()) { + case PPC::COND_BRANCH: + // while this will be 4 most of the time, if we emit 12 it is just a + // minor pessimization that saves us from having to worry about + // keeping the offsets up to date later when we emit long branch glue. + return 12; + case PPC::IMPLICIT_DEF_GPR: // no asm emitted + case PPC::IMPLICIT_DEF_F4: // no asm emitted + case PPC::IMPLICIT_DEF_F8: // no asm emitted + return 0; + case PPC::INLINEASM: // Inline Asm: Variable size. + for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) + if (MI->getOperand(i).isExternalSymbol()) { + const char *AsmStr = MI->getOperand(i).getSymbolName(); + // Count the number of newline's in the asm string. + unsigned NumInstrs = 0; + for (; *AsmStr; ++AsmStr) + NumInstrs += *AsmStr == '\n'; + return NumInstrs*4; + } + assert(0 && "INLINEASM didn't have format string??"); + default: + return 4; // PowerPC instructions are all 4 bytes + } } + + +bool PPCBSel::runOnMachineFunction(MachineFunction &Fn) { + // Running total of instructions encountered since beginning of function + unsigned ByteCount = 0; + + // For each MBB, add its offset to the offset map, and count up its + // instructions + for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E; + ++MFI) { + MachineBasicBlock *MBB = MFI; + OffsetMap[MBB] = ByteCount; + + for (MachineBasicBlock::iterator MBBI = MBB->begin(), EE = MBB->end(); + MBBI != EE; ++MBBI) + ByteCount += getNumBytesForInstruction(MBBI); + } + + // We're about to run over the MBB's again, so reset the ByteCount + ByteCount = 0; + + // For each MBB, find the conditional branch pseudo instructions, and + // calculate the difference between the target MBB and the current ICount + // to decide whether or not to emit a short or long branch. + // + // short branch: + // bCC .L_TARGET_MBB + // + // long branch: + // bInverseCC $PC+8 + // b .L_TARGET_MBB + // b .L_FALLTHROUGH_MBB + for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E; + ++MFI) { + MachineBasicBlock *MBB = MFI; + + for (MachineBasicBlock::iterator MBBI = MBB->begin(), EE = MBB->end(); + MBBI != EE; ++MBBI) { + // We may end up deleting the MachineInstr that MBBI points to, so + // remember its opcode now so we can refer to it after calling erase() + unsigned ByteSize = getNumBytesForInstruction(MBBI); + if (MBBI->getOpcode() == PPC::COND_BRANCH) { + MachineBasicBlock::iterator MBBJ = MBBI; + ++MBBJ; + + // condbranch operands: + // 0. CR0 register + // 1. bc opcode + // 2. target MBB + // 3. fallthrough MBB + MachineBasicBlock *trueMBB = + MBBI->getOperand(2).getMachineBasicBlock(); + MachineBasicBlock *falseMBB = + MBBI->getOperand(3).getMachineBasicBlock(); + + int Displacement = OffsetMap[trueMBB] - ByteCount; + unsigned Opcode = MBBI->getOperand(1).getImmedValue(); + unsigned CRReg = MBBI->getOperand(0).getReg(); + unsigned Inverted = PPCInstrInfo::invertPPCBranchOpcode(Opcode); + + if (Displacement >= -32768 && Displacement <= 32767) { + BuildMI(*MBB, MBBJ, Opcode, 2).addReg(CRReg).addMBB(trueMBB); + } else { + BuildMI(*MBB, MBBJ, Inverted, 2).addReg(CRReg).addSImm(8); + BuildMI(*MBB, MBBJ, PPC::B, 1).addMBB(trueMBB); + BuildMI(*MBB, MBBJ, PPC::B, 1).addMBB(falseMBB); + } + + // Erase the psuedo COND_BRANCH instruction, and then back up the + // iterator so that when the for loop increments it, we end up in + // the correct place rather than iterating off the end. + MBB->erase(MBBI); + MBBI = --MBBJ; + } + ByteCount += ByteSize; + } + } + + OffsetMap.clear(); + return true; +} + |