Add a new interface to allow IR-level passes to access codegen-specific information.

[oota-llvm.git] / lib / CodeGen / MachineCSE.cpp

diff --git a/lib/CodeGen/MachineCSE.cpp b/lib/CodeGen/MachineCSE.cpp
index 5153abbc4e1160589ca47bc47923408d3b5ed4a2..896461fd194b52936db2b67755f419337cf91cfe 100644 (file)
--- a/lib/CodeGen/MachineCSE.cpp
+++ b/lib/CodeGen/MachineCSE.cpp
@@ -215,8 +215,10 @@ bool MachineCSE::hasLivePhysRegDefUses(const MachineInstr *MI,
     if (MO.isDef() &&
         (MO.isDead() || isPhysDefTriviallyDead(Reg, I, MBB->end())))
       continue;
-    for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
-      PhysRefs.insert(*AI);
+    // Reading constant physregs is ok.
+    if (!MRI->isConstantPhysReg(Reg, *MBB->getParent()))
+      for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
+        PhysRefs.insert(*AI);
     if (MO.isDef())
       PhysDefs.push_back(Reg);
   }