[LLVMbugs] [Bug 11363] New: InlineSpiller won't remat before tied use

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=11363

             Bug #: 11363
           Summary: InlineSpiller won't remat before tied use
           Product: libraries
           Version: trunk
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Register Allocator
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: stoklund at 2pi.dk
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified


InlineSpiller refuses to rematerialize values before a tied use:


  tie(Reads, Writes) = MI->readsWritesVirtualRegister(VirtReg.reg, &Ops);
  if (Writes) {
    for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
      MachineOperand &MO = MI->getOperand(Ops[i]);
      if (MO.isUse() ? MI->isRegTiedToDefOperand(Ops[i]) : MO.getSubReg()) {
        markValueUsed(&VirtReg, ParentVNI);
        DEBUG(dbgs() << "\tcannot remat tied reg: " << UseIdx << '\t' << *MI);
        return false;
      }
    }
  }

It should remat and insert a spill at the same time.

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