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| author | Bill Wendling <isanbard@gmail.com> | 2008-05-12 22:15:05 +0000 |
|---|---|---|
| committer | Bill Wendling <isanbard@gmail.com> | 2008-05-12 22:15:05 +0000 |
| commit | 49beda209a4c747cea107880a99108fb058cfd49 (patch) | |
| tree | 4bf9939f61db23f5584b53280ef9d5fb19fc1c23 /lib/CodeGen | |
| parent | b1cc130858da63a2070398273e9874da61f6260b (diff) | |
| download | external_llvm-49beda209a4c747cea107880a99108fb058cfd49.zip external_llvm-49beda209a4c747cea107880a99108fb058cfd49.tar.gz external_llvm-49beda209a4c747cea107880a99108fb058cfd49.tar.bz2 | |
Constify isSourceDefinedByImplicitDef function. Otherwise, just formatting
changes that don't change functionality.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51004 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen')
| -rw-r--r-- | lib/CodeGen/PHIElimination.cpp | 83 |
1 files changed, 38 insertions, 45 deletions
diff --git a/lib/CodeGen/PHIElimination.cpp b/lib/CodeGen/PHIElimination.cpp index 8b1f307..601bfd6 100644 --- a/lib/CodeGen/PHIElimination.cpp +++ b/lib/CodeGen/PHIElimination.cpp @@ -127,11 +127,11 @@ bool PNE::EliminatePHINodes(MachineFunction &MF, MachineBasicBlock &MBB) { return true; } -static bool isSourceDefinedByImplicitDef(MachineInstr *MPhi, - MachineRegisterInfo *MRI) { +static bool isSourceDefinedByImplicitDef(const MachineInstr *MPhi, + const MachineRegisterInfo *MRI) { for (unsigned i = 1; i != MPhi->getNumOperands(); i += 2) { unsigned SrcReg = MPhi->getOperand(i).getReg(); - MachineInstr *DefMI = MRI->getVRegDef(SrcReg); + const MachineInstr *DefMI = MRI->getVRegDef(SrcReg); if (!DefMI || DefMI->getOpcode() != TargetInstrInfo::IMPLICIT_DEF) return false; } @@ -142,6 +142,7 @@ static bool isSourceDefinedByImplicitDef(MachineInstr *MPhi, /// under the assuption that it needs to be lowered in a way that supports /// atomic execution of PHIs. This lowering method is always correct all of the /// time. +/// void PNE::LowerAtomicPHINode(MachineBasicBlock &MBB, MachineBasicBlock::iterator AfterPHIsIt) { // Unlink the PHI node from the basic block, but don't delete the PHI yet. @@ -155,10 +156,9 @@ void PNE::LowerAtomicPHINode(MachineBasicBlock &MBB, const TargetRegisterClass *RC = MF.getRegInfo().getRegClass(DestReg); unsigned IncomingReg = MF.getRegInfo().createVirtualRegister(RC); - // Insert a register to register copy in the top of the current block (but + // Insert a register to register copy at the top of the current block (but // after any remaining phi nodes) which copies the new incoming register // into the phi node destination. - // const TargetInstrInfo *TII = MF.getTarget().getInstrInfo(); if (isSourceDefinedByImplicitDef(MPhi, MRI)) // If all sources of a PHI node are implicit_def, just emit an implicit_def @@ -167,7 +167,7 @@ void PNE::LowerAtomicPHINode(MachineBasicBlock &MBB, else TII->copyRegToReg(MBB, AfterPHIsIt, DestReg, IncomingReg, RC, RC); - // Update live variable information if there is any... + // Update live variable information if there is any. LiveVariables *LV = getAnalysisToUpdate<LiveVariables>(); if (LV) { MachineInstr *PHICopy = prior(AfterPHIsIt); @@ -177,15 +177,13 @@ void PNE::LowerAtomicPHINode(MachineBasicBlock &MBB, // Add information to LiveVariables to know that the incoming value is // killed. Note that because the value is defined in several places (once - // each for each incoming block), the "def" block and instruction fields - // for the VarInfo is not filled in. - // + // each for each incoming block), the "def" block and instruction fields for + // the VarInfo is not filled in. LV->addVirtualRegisterKilled(IncomingReg, PHICopy); - // Since we are going to be deleting the PHI node, if it is the last use - // of any registers, or if the value itself is dead, we need to move this + // Since we are going to be deleting the PHI node, if it is the last use of + // any registers, or if the value itself is dead, we need to move this // information over to the new copy we just inserted. - // LV->removeVirtualRegistersKilled(MPhi); // If the result is dead, update LV. @@ -197,41 +195,39 @@ void PNE::LowerAtomicPHINode(MachineBasicBlock &MBB, LV->getVarInfo(IncomingReg).UsedBlocks[MBB.getNumber()] = true; } - // Adjust the VRegPHIUseCount map to account for the removal of this PHI - // node. + // Adjust the VRegPHIUseCount map to account for the removal of this PHI node. for (unsigned i = 1; i != MPhi->getNumOperands(); i += 2) --VRegPHIUseCount[BBVRegPair(MPhi->getOperand(i + 1).getMBB(), MPhi->getOperand(i).getReg())]; - // Now loop over all of the incoming arguments, changing them to copy into - // the IncomingReg register in the corresponding predecessor basic block. - // + // Now loop over all of the incoming arguments, changing them to copy into the + // IncomingReg register in the corresponding predecessor basic block. SmallPtrSet<MachineBasicBlock*, 8> MBBsInsertedInto; for (int i = NumSrcs - 1; i >= 0; --i) { unsigned SrcReg = MPhi->getOperand(i*2+1).getReg(); assert(TargetRegisterInfo::isVirtualRegister(SrcReg) && "Machine PHI Operands must all be virtual registers!"); - // If source is defined by an implicit def, there is no need to insert - // a copy unless it's the only source. + // If source is defined by an implicit def, there is no need to insert a + // copy unless it's the only source. MachineInstr *DefMI = MRI->getVRegDef(SrcReg); if (DefMI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF) { ImpDefs.insert(DefMI); continue; } - // Get the MachineBasicBlock equivalent of the BasicBlock that is the - // source path the PHI. + // Get the MachineBasicBlock equivalent of the BasicBlock that is the source + // path the PHI. MachineBasicBlock &opBlock = *MPhi->getOperand(i*2+2).getMBB(); // Check to make sure we haven't already emitted the copy for this block. - // This can happen because PHI nodes may have multiple entries for the - // same basic block. + // This can happen because PHI nodes may have multiple entries for the same + // basic block. if (!MBBsInsertedInto.insert(&opBlock)) continue; // If the copy has already been emitted, we're done. - // Find a safe location to insert the copy, this may be the first - // terminator in the block (or end()). + // Find a safe location to insert the copy, this may be the first terminator + // in the block (or end()). MachineBasicBlock::iterator InsertPos = opBlock.getFirstTerminator(); // Insert the copy. @@ -240,26 +236,24 @@ void PNE::LowerAtomicPHINode(MachineBasicBlock &MBB, // Now update live variable information if we have it. Otherwise we're done if (!LV) continue; - // We want to be able to insert a kill of the register if this PHI - // (aka, the copy we just inserted) is the last use of the source - // value. Live variable analysis conservatively handles this by - // saying that the value is live until the end of the block the PHI - // entry lives in. If the value really is dead at the PHI copy, there - // will be no successor blocks which have the value live-in. - // - // Check to see if the copy is the last use, and if so, update the - // live variables information so that it knows the copy source - // instruction kills the incoming value. + // We want to be able to insert a kill of the register if this PHI (aka, the + // copy we just inserted) is the last use of the source value. Live + // variable analysis conservatively handles this by saying that the value is + // live until the end of the block the PHI entry lives in. If the value + // really is dead at the PHI copy, there will be no successor blocks which + // have the value live-in. // + // Check to see if the copy is the last use, and if so, update the live + // variables information so that it knows the copy source instruction kills + // the incoming value. LiveVariables::VarInfo &InRegVI = LV->getVarInfo(SrcReg); InRegVI.UsedBlocks[opBlock.getNumber()] = true; - // Loop over all of the successors of the basic block, checking to see - // if the value is either live in the block, or if it is killed in the - // block. Also check to see if this register is in use by another PHI - // node which has not yet been eliminated. If so, it will be killed - // at an appropriate point later. - // + // Loop over all of the successors of the basic block, checking to see if + // the value is either live in the block, or if it is killed in the block. + // Also check to see if this register is in use by another PHI node which + // has not yet been eliminated. If so, it will be killed at an appropriate + // point later. // Is it used by any PHI instructions in this block? bool ValueIsLive = VRegPHIUseCount[BBVRegPair(&opBlock, SrcReg)] != 0; @@ -316,12 +310,11 @@ void PNE::LowerAtomicPHINode(MachineBasicBlock &MBB, } } - // Okay, if we now know that the value is not live out of the block, - // we can add a kill marker in this block saying that it kills the incoming - // value! + // Okay, if we now know that the value is not live out of the block, we can + // add a kill marker in this block saying that it kills the incoming value! if (!ValueIsLive) { // In our final twist, we have to decide which instruction kills the - // register. In most cases this is the copy, however, the first + // register. In most cases this is the copy, however, the first // terminator instruction at the end of the block may also use the value. // In this case, we should mark *it* as being the killing block, not the // copy. |