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author | Bill Wendling <isanbard@gmail.com> | 2010-08-02 22:06:08 +0000 |
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committer | Bill Wendling <isanbard@gmail.com> | 2010-08-02 22:06:08 +0000 |
commit | 94e4008fbaa85600777b55605098bfd9cc3b9294 (patch) | |
tree | f5c8c83edb7c9f913bb3f546eacece7d1ae3beea | |
parent | 5510e5e9b5c82063ed63a76632878135f2e9e67b (diff) | |
download | external_llvm-94e4008fbaa85600777b55605098bfd9cc3b9294.zip external_llvm-94e4008fbaa85600777b55605098bfd9cc3b9294.tar.gz external_llvm-94e4008fbaa85600777b55605098bfd9cc3b9294.tar.bz2 |
Early exit and reduce indentation. No functionality change.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110069 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | lib/CodeGen/OptimizeExts.cpp | 211 |
1 files changed, 106 insertions, 105 deletions
diff --git a/lib/CodeGen/OptimizeExts.cpp b/lib/CodeGen/OptimizeExts.cpp index 4973911..586b84c 100644 --- a/lib/CodeGen/OptimizeExts.cpp +++ b/lib/CodeGen/OptimizeExts.cpp @@ -78,119 +78,120 @@ FunctionPass *llvm::createOptimizeExtsPass() { return new OptimizeExts(); } /// ignore all debug uses. bool OptimizeExts::OptimizeInstr(MachineInstr *MI, MachineBasicBlock *MBB, SmallPtrSet<MachineInstr*, 8> &LocalMIs) { - bool Changed = false; LocalMIs.insert(MI); unsigned SrcReg, DstReg, SubIdx; - if (TII->isCoalescableExtInstr(*MI, SrcReg, DstReg, SubIdx)) { - if (TargetRegisterInfo::isPhysicalRegister(DstReg) || - TargetRegisterInfo::isPhysicalRegister(SrcReg)) - return false; - - MachineRegisterInfo::use_nodbg_iterator UI = MRI->use_nodbg_begin(SrcReg); - if (++UI == MRI->use_nodbg_end()) - // No other uses. - return false; - - // Ok, the source has other uses. See if we can replace the other uses - // with use of the result of the extension. - SmallPtrSet<MachineBasicBlock*, 4> ReachedBBs; - UI = MRI->use_nodbg_begin(DstReg); - for (MachineRegisterInfo::use_nodbg_iterator UE = MRI->use_nodbg_end(); - UI != UE; ++UI) - ReachedBBs.insert(UI->getParent()); + if (!TII->isCoalescableExtInstr(*MI, SrcReg, DstReg, SubIdx)) + return false; + + if (TargetRegisterInfo::isPhysicalRegister(DstReg) || + TargetRegisterInfo::isPhysicalRegister(SrcReg)) + return false; + + MachineRegisterInfo::use_nodbg_iterator UI = MRI->use_nodbg_begin(SrcReg); + if (++UI == MRI->use_nodbg_end()) + // No other uses. + return false; + + // Ok, the source has other uses. See if we can replace the other uses + // with use of the result of the extension. + SmallPtrSet<MachineBasicBlock*, 4> ReachedBBs; + UI = MRI->use_nodbg_begin(DstReg); + for (MachineRegisterInfo::use_nodbg_iterator UE = MRI->use_nodbg_end(); + UI != UE; ++UI) + ReachedBBs.insert(UI->getParent()); + + bool ExtendLife = true; + // Uses that are in the same BB of uses of the result of the instruction. + SmallVector<MachineOperand*, 8> Uses; + // Uses that the result of the instruction can reach. + SmallVector<MachineOperand*, 8> ExtendedUses; + + UI = MRI->use_nodbg_begin(SrcReg); + for (MachineRegisterInfo::use_nodbg_iterator UE = MRI->use_nodbg_end(); + UI != UE; ++UI) { + MachineOperand &UseMO = UI.getOperand(); + MachineInstr *UseMI = &*UI; + if (UseMI == MI) + continue; + if (UseMI->isPHI()) { + ExtendLife = false; + continue; + } - bool ExtendLife = true; - // Uses that are in the same BB of uses of the result of the instruction. - SmallVector<MachineOperand*, 8> Uses; - // Uses that the result of the instruction can reach. - SmallVector<MachineOperand*, 8> ExtendedUses; + // It's an error to translate this: + // + // %reg1025 = <sext> %reg1024 + // ... + // %reg1026 = SUBREG_TO_REG 0, %reg1024, 4 + // + // into this: + // + // %reg1025 = <sext> %reg1024 + // ... + // %reg1027 = COPY %reg1025:4 + // %reg1026 = SUBREG_TO_REG 0, %reg1027, 4 + // + // The problem here is that SUBREG_TO_REG is there to assert that an + // implicit zext occurs. It doesn't insert a zext instruction. If we allow + // the COPY here, it will give us the value after the <sext>, not the + // original value of %reg1024 before <sext>. + if (UseMI->getOpcode() == TargetOpcode::SUBREG_TO_REG) + continue; + + MachineBasicBlock *UseMBB = UseMI->getParent(); + if (UseMBB == MBB) { + // Local uses that come after the extension. + if (!LocalMIs.count(UseMI)) + Uses.push_back(&UseMO); + } else if (ReachedBBs.count(UseMBB)) + // Non-local uses where the result of extension is used. Always replace + // these unless it's a PHI. + Uses.push_back(&UseMO); + else if (Aggressive && DT->dominates(MBB, UseMBB)) + // We may want to extend live range of the extension result in order to + // replace these uses. + ExtendedUses.push_back(&UseMO); + else { + // Both will be live out of the def MBB anyway. Don't extend live range of + // the extension result. + ExtendLife = false; + break; + } + } - UI = MRI->use_nodbg_begin(SrcReg); - for (MachineRegisterInfo::use_nodbg_iterator UE = MRI->use_nodbg_end(); - UI != UE; ++UI) { - MachineOperand &UseMO = UI.getOperand(); - MachineInstr *UseMI = &*UI; - if (UseMI == MI) - continue; - if (UseMI->isPHI()) { - ExtendLife = false; - continue; - } + if (ExtendLife && !ExtendedUses.empty()) + // Ok, we'll extend the liveness of the extension result. + std::copy(ExtendedUses.begin(), ExtendedUses.end(), + std::back_inserter(Uses)); - // It's an error to translate this: - // - // %reg1025 = <sext> %reg1024 - // ... - // %reg1026 = SUBREG_TO_REG 0, %reg1024, 4 - // - // into this: - // - // %reg1025 = <sext> %reg1024 - // ... - // %reg1027 = COPY %reg1025:4 - // %reg1026 = SUBREG_TO_REG 0, %reg1027, 4 - // - // The problem here is that SUBREG_TO_REG is there to assert that an - // implicit zext occurs. It doesn't insert a zext instruction. If we allow - // the COPY here, it will give us the value after the <sext>, - // not the original value of %reg1024 before <sext>. - if (UseMI->getOpcode() == TargetOpcode::SUBREG_TO_REG) - continue; + // Now replace all uses. + bool Changed = false; + if (!Uses.empty()) { + SmallPtrSet<MachineBasicBlock*, 4> PHIBBs; + // Look for PHI uses of the extended result, we don't want to extend the + // liveness of a PHI input. It breaks all kinds of assumptions down + // stream. A PHI use is expected to be the kill of its source values. + UI = MRI->use_nodbg_begin(DstReg); + for (MachineRegisterInfo::use_nodbg_iterator UE = MRI->use_nodbg_end(); + UI != UE; ++UI) + if (UI->isPHI()) + PHIBBs.insert(UI->getParent()); + const TargetRegisterClass *RC = MRI->getRegClass(SrcReg); + for (unsigned i = 0, e = Uses.size(); i != e; ++i) { + MachineOperand *UseMO = Uses[i]; + MachineInstr *UseMI = UseMO->getParent(); MachineBasicBlock *UseMBB = UseMI->getParent(); - if (UseMBB == MBB) { - // Local uses that come after the extension. - if (!LocalMIs.count(UseMI)) - Uses.push_back(&UseMO); - } else if (ReachedBBs.count(UseMBB)) - // Non-local uses where the result of extension is used. Always - // replace these unless it's a PHI. - Uses.push_back(&UseMO); - else if (Aggressive && DT->dominates(MBB, UseMBB)) - // We may want to extend live range of the extension result in order - // to replace these uses. - ExtendedUses.push_back(&UseMO); - else { - // Both will be live out of the def MBB anyway. Don't extend live - // range of the extension result. - ExtendLife = false; - break; - } - } - - if (ExtendLife && !ExtendedUses.empty()) - // Ok, we'll extend the liveness of the extension result. - std::copy(ExtendedUses.begin(), ExtendedUses.end(), - std::back_inserter(Uses)); - - // Now replace all uses. - if (!Uses.empty()) { - SmallPtrSet<MachineBasicBlock*, 4> PHIBBs; - // Look for PHI uses of the extended result, we don't want to extend the - // liveness of a PHI input. It breaks all kinds of assumptions down - // stream. A PHI use is expected to be the kill of its source values. - UI = MRI->use_nodbg_begin(DstReg); - for (MachineRegisterInfo::use_nodbg_iterator UE = MRI->use_nodbg_end(); - UI != UE; ++UI) - if (UI->isPHI()) - PHIBBs.insert(UI->getParent()); - - const TargetRegisterClass *RC = MRI->getRegClass(SrcReg); - for (unsigned i = 0, e = Uses.size(); i != e; ++i) { - MachineOperand *UseMO = Uses[i]; - MachineInstr *UseMI = UseMO->getParent(); - MachineBasicBlock *UseMBB = UseMI->getParent(); - if (PHIBBs.count(UseMBB)) - continue; - unsigned NewVR = MRI->createVirtualRegister(RC); - BuildMI(*UseMBB, UseMI, UseMI->getDebugLoc(), - TII->get(TargetOpcode::COPY), NewVR) - .addReg(DstReg, 0, SubIdx); - UseMO->setReg(NewVR); - ++NumReuse; - Changed = true; - } + if (PHIBBs.count(UseMBB)) + continue; + unsigned NewVR = MRI->createVirtualRegister(RC); + BuildMI(*UseMBB, UseMI, UseMI->getDebugLoc(), + TII->get(TargetOpcode::COPY), NewVR) + .addReg(DstReg, 0, SubIdx); + UseMO->setReg(NewVR); + ++NumReuse; + Changed = true; } } |