Fill out codegen SSA updater. It's not yet tested.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90395 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index f73a5a3..ba9be6a 100644
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -1058,6 +1058,20 @@
return true;
}
+/// isConstantValuePHI - If the specified instruction is a PHI that always
+/// merges together the same virtual register, return the register, otherwise
+/// return 0.
+unsigned MachineInstr::isConstantValuePHI() const {
+ if (getOpcode() != TargetInstrInfo::PHI)
+ return 0;
+
+ unsigned Reg = getOperand(1).getReg();
+ for (unsigned i = 3, e = getNumOperands(); i < e; i += 2)
+ if (getOperand(i).getReg() != Reg)
+ return 0;
+ return Reg;
+}
+
void MachineInstr::dump() const {
errs() << " " << *this;
}