diff options
Diffstat (limited to 'llvm/lib/CodeGen')
| -rw-r--r-- | llvm/lib/CodeGen/PeepholeOptimizer.cpp | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/PeepholeOptimizer.cpp b/llvm/lib/CodeGen/PeepholeOptimizer.cpp index fb3e648..729a57e 100644 --- a/llvm/lib/CodeGen/PeepholeOptimizer.cpp +++ b/llvm/lib/CodeGen/PeepholeOptimizer.cpp @@ -1203,6 +1203,18 @@ bool PeepholeOptimizer::optimizeCoalescableCopyImpl(Rewriter &&CpyRewriter) { if (!NewSrc.Reg) continue; + if (NewSrc.SubReg) { + // Verify the register class supports the subregister index. ARM's + // copy-like queries return register:subreg pairs where the register's + // current class does not directly support the subregister index. + const TargetRegisterClass *RC = MRI->getRegClass(NewSrc.Reg); + const TargetRegisterClass *WithSubRC = + TRI->getSubClassWithSubReg(RC, NewSrc.SubReg); + if (!MRI->constrainRegClass(NewSrc.Reg, WithSubRC)) + continue; + Changed = true; + } + // Rewrite source. if (CpyRewriter.RewriteCurrentSource(NewSrc.Reg, NewSrc.SubReg)) { // We may have extended the live-range of NewSrc, account for that. @@ -1275,6 +1287,18 @@ MachineInstr &PeepholeOptimizer::rewriteSource(MachineInstr &CopyLike, const TargetRegisterClass *DefRC = MRI->getRegClass(Def.Reg); Register NewVReg = MRI->createVirtualRegister(DefRC); + if (NewSrc.SubReg) { + const TargetRegisterClass *NewSrcRC = MRI->getRegClass(NewSrc.Reg); + const TargetRegisterClass *WithSubRC = + TRI->getSubClassWithSubReg(NewSrcRC, NewSrc.SubReg); + + // The new source may not directly support the subregister, but we should be + // able to assume it is constrainable to support the subregister (otherwise + // ValueTracker was lying and reported a useless value). + if (!MRI->constrainRegClass(NewSrc.Reg, WithSubRC)) + llvm_unreachable("replacement register cannot support subregister"); + } + MachineInstr *NewCopy = BuildMI(*CopyLike.getParent(), &CopyLike, CopyLike.getDebugLoc(), TII->get(TargetOpcode::COPY), NewVReg) |