Handle register mask operands in setPhysRegsDeadExcept().

Calls that use register mask operands don't have implicit defs for
returned values.  The register mask operand handles the call clobber,
but it always behaves like a set of dead defs.

Add live implicit defs for any implicitly defined physregs that are
actually used.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149715 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 15 insertions, 0 deletions

diff --git a/include/llvm/CodeGen/MachineInstr.h b/include/llvm/CodeGen/MachineInstr.h
index 22a7ef2..4ccc372 100644
--- a/include/llvm/CodeGen/MachineInstr.h
+++ b/include/llvm/CodeGen/MachineInstr.h
@@ -792,6 +792,9 @@ public:
 
   /// setPhysRegsDeadExcept - Mark every physreg used by this instruction as
   /// dead except those in the UsedRegs list.
+  ///
+  /// On instructions with register mask operands, also add implicit-def
+  /// operands for all registers in UsedRegs.
   void setPhysRegsDeadExcept(ArrayRef<unsigned> UsedRegs,
                              const TargetRegisterInfo &TRI);
 
diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index 6ce01a46..de2082a 100644
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -1795,8 +1795,13 @@ void MachineInstr::addRegisterDefined(unsigned IncomingReg,
 
 void MachineInstr::setPhysRegsDeadExcept(ArrayRef<unsigned> UsedRegs,
                                          const TargetRegisterInfo &TRI) {
+  bool HasRegMask = false;
   for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
     MachineOperand &MO = getOperand(i);
+    if (MO.isRegMask()) {
+      HasRegMask = true;
+      continue;
+    }
     if (!MO.isReg() || !MO.isDef()) continue;
     unsigned Reg = MO.getReg();
     if (!TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
@@ -1810,6 +1815,13 @@ void MachineInstr::setPhysRegsDeadExcept(ArrayRef<unsigned> UsedRegs,
     // If there are no uses, including partial uses, the def is dead.
     if (Dead) MO.setIsDead();
   }
+
+  // This is a call with a register mask operand.
+  // Mask clobbers are always dead, so add defs for the non-dead defines.
+  if (HasRegMask)
+    for (ArrayRef<unsigned>::iterator I = UsedRegs.begin(), E = UsedRegs.end();
+         I != E; ++I)
+      addRegisterDefined(*I, &TRI);
 }
 
 unsigned