[llvm-commits] [llvm] r122218 - /llvm/trunk/lib/CodeGen/MachineVerifier.cpp

[Cameron Zwarich]

Author: zwarich
Date: Sun Dec 19 19:22:37 2010
New Revision: 122218

URL: http://llvm.org/viewvc/llvm-project?rev=122218&view=rev
Log:
Don't assume that an instruction ending a register's live range always reads
the register; it may be a dead def instead. Fixes PR8820.

Modified:
    llvm/trunk/lib/CodeGen/MachineVerifier.cpp

Modified: llvm/trunk/lib/CodeGen/MachineVerifier.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineVerifier.cpp?rev=122218&r1=122217&r2=122218&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineVerifier.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineVerifier.cpp Sun Dec 19 19:22:37 2010
@@ -1072,10 +1072,24 @@
             << MBBStartIdx << '\n';
         } else if (TargetRegisterInfo::isVirtualRegister(LI.reg) &&
                    !MI->readsVirtualRegister(LI.reg)) {
-          // FIXME: Should we require a kill flag?
-          report("Instruction killing live segment doesn't read register", MI);
-          I->print(*OS);
-          *OS << " in " << LI << '\n';
+          // A live range can end with either a redefinition, a kill flag on a
+          // use, or a dead flag on a def.
+          // FIXME: Should we check for each of these?
+          bool hasDeadDef = false;
+          for (MachineInstr::const_mop_iterator MOI = MI->operands_begin(),
+               MOE = MI->operands_end(); MOI != MOE; ++MOI) {
+            if (MOI->isReg() && MOI->isDef() && MOI->isDead()) {
+              hasDeadDef = true;
+              break;
+            }
+          }
+
+          if (!hasDeadDef) {
+            report("Instruction killing live segment neither defines nor reads "
+                   "register", MI);
+            I->print(*OS);
+            *OS << " in " << LI << '\n';
+          }
         }
       }