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author | Evan Cheng <evan.cheng@apple.com> | 2008-09-11 20:07:10 +0000 |
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committer | Evan Cheng <evan.cheng@apple.com> | 2008-09-11 20:07:10 +0000 |
commit | 8db866808c803f9bdcd45c56a042fedd8cccd5bc (patch) | |
tree | 0616d920ec6af7dc1ea68c275f8065140b736e13 /lib/CodeGen | |
parent | ac34a00fe0784cd6efc466f03f93ab1017fa9726 (diff) | |
download | external_llvm-8db866808c803f9bdcd45c56a042fedd8cccd5bc.zip external_llvm-8db866808c803f9bdcd45c56a042fedd8cccd5bc.tar.gz external_llvm-8db866808c803f9bdcd45c56a042fedd8cccd5bc.tar.bz2 |
Fix PR2748. Avoid coalescing physical register with virtual register which would create illegal extract_subreg. e.g.
vr1024 = extract_subreg vr1025, 1
...
vr1024 = mov8rr AH
If vr1024 is coalesced with AH, the extract_subreg is now illegal since AH does not have a super-reg whose sub-register 1 is AH.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56118 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen')
-rw-r--r-- | lib/CodeGen/SimpleRegisterCoalescing.cpp | 63 | ||||
-rw-r--r-- | lib/CodeGen/SimpleRegisterCoalescing.h | 7 |
2 files changed, 70 insertions, 0 deletions
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp index 2d4d590..7619dd5 100644 --- a/lib/CodeGen/SimpleRegisterCoalescing.cpp +++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp @@ -875,6 +875,8 @@ void SimpleRegisterCoalescing::RemoveCopiesFromValNo(LiveInterval &li, } } +/// getMatchingSuperReg - Return a super-register of the specified register +/// Reg so its sub-register of index SubIdx is Reg. static unsigned getMatchingSuperReg(unsigned Reg, unsigned SubIdx, const TargetRegisterClass *RC, const TargetRegisterInfo* TRI) { @@ -919,6 +921,61 @@ SimpleRegisterCoalescing::isProfitableToCoalesceToSubRC(unsigned SrcReg, return (SrcSize + DstSize) <= Threshold; } +/// HasIncompatibleSubRegDefUse - If we are trying to coalesce a virtual +/// register with a physical register, check if any of the virtual register +/// operand is a sub-register use or def. If so, make sure it won't result +/// in an illegal extract_subreg or insert_subreg instruction. e.g. +/// vr1024 = extract_subreg vr1025, 1 +/// ... +/// vr1024 = mov8rr AH +/// If vr1024 is coalesced with AH, the extract_subreg is now illegal since +/// AH does not have a super-reg whose sub-register 1 is AH. +bool +SimpleRegisterCoalescing::HasIncompatibleSubRegDefUse(MachineInstr *CopyMI, + unsigned VirtReg, + unsigned PhysReg) { + for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(VirtReg), + E = mri_->reg_end(); I != E; ++I) { + MachineOperand &O = I.getOperand(); + MachineInstr *MI = &*I; + if (MI == CopyMI || JoinedCopies.count(MI)) + continue; + unsigned SubIdx = O.getSubReg(); + if (SubIdx && !tri_->getSubReg(PhysReg, SubIdx)) + return true; + if (MI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG) { + SubIdx = MI->getOperand(2).getImm(); + if (O.isUse() && !tri_->getSubReg(PhysReg, SubIdx)) + return true; + if (O.isDef()) { + unsigned SrcReg = MI->getOperand(1).getReg(); + const TargetRegisterClass *RC = + TargetRegisterInfo::isPhysicalRegister(SrcReg) + ? tri_->getPhysicalRegisterRegClass(SrcReg) + : mri_->getRegClass(SrcReg); + if (!getMatchingSuperReg(PhysReg, SubIdx, RC, tri_)) + return true; + } + } + if (MI->getOpcode() == TargetInstrInfo::INSERT_SUBREG) { + SubIdx = MI->getOperand(3).getImm(); + if (VirtReg == MI->getOperand(0).getReg()) { + if (!tri_->getSubReg(PhysReg, SubIdx)) + return true; + } else { + unsigned DstReg = MI->getOperand(0).getReg(); + const TargetRegisterClass *RC = + TargetRegisterInfo::isPhysicalRegister(DstReg) + ? tri_->getPhysicalRegisterRegClass(DstReg) + : mri_->getRegClass(DstReg); + if (!getMatchingSuperReg(PhysReg, SubIdx, RC, tri_)) + return true; + } + } + } + return false; +} + /// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg, /// which are the src/dst of the copy instruction CopyMI. This returns true @@ -1111,6 +1168,12 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) { return false; } } + + // Will it create illegal extract_subreg / insert_subreg? + if (SrcIsPhys && HasIncompatibleSubRegDefUse(CopyMI, DstReg, SrcReg)) + return false; + if (DstIsPhys && HasIncompatibleSubRegDefUse(CopyMI, SrcReg, DstReg)) + return false; LiveInterval &SrcInt = li_->getInterval(SrcReg); LiveInterval &DstInt = li_->getInterval(DstReg); diff --git a/lib/CodeGen/SimpleRegisterCoalescing.h b/lib/CodeGen/SimpleRegisterCoalescing.h index 41d1dfb..39c9071 100644 --- a/lib/CodeGen/SimpleRegisterCoalescing.h +++ b/lib/CodeGen/SimpleRegisterCoalescing.h @@ -223,6 +223,13 @@ namespace llvm { bool isProfitableToCoalesceToSubRC(unsigned SrcReg, unsigned DstReg, MachineBasicBlock *MBB); + /// HasIncompatibleSubRegDefUse - If we are trying to coalesce a virtual + /// register with a physical register, check if any of the virtual register + /// operand is a sub-register use or def. If so, make sure it won't result + /// in an illegal extract_subreg or insert_subreg instruction. + bool HasIncompatibleSubRegDefUse(MachineInstr *CopyMI, + unsigned VirtReg, unsigned PhysReg); + /// RangeIsDefinedByCopyFromReg - Return true if the specified live range of /// the specified live interval is defined by a copy from the specified /// register. |