Teach regular and fast isel to set dead flags on unused implicit defs

on calls and similar instructions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106353 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/FastISel.h

@@ -36,6 +36,7 @@ class TargetInstrInfo;
 class TargetLowering;
 class TargetMachine;
 class TargetRegisterClass;
+class TargetRegisterInfo;
 
 /// FastISel - This is a fast-path instruction selection class that
 /// generates poor code and doesn't support illegal types or non-trivial
@@ -60,6 +61,7 @@ protected:
   const TargetData &TD;
   const TargetInstrInfo &TII;
   const TargetLowering &TLI;
+  const TargetRegisterInfo &TRI;
   bool IsBottomUp;
 
 public:

include/llvm/CodeGen/MachineInstr.h

@@ -364,6 +364,11 @@ public:
   void addRegisterDefined(unsigned IncomingReg,
                           const TargetRegisterInfo *RegInfo = 0);
 
+  /// setPhysRegsDeadExcept - Mark every physreg used by this instruction as dead
+  /// except those in the UsedRegs list.
+  void setPhysRegsDeadExcept(const SmallVectorImpl<unsigned> &UsedRegs,
+                             const TargetRegisterInfo &TRI);
+
   /// isSafeToMove - Return true if it is safe to move this instruction. If
   /// SawStore is set to true, it means that there is a store (or call) between
   /// the instruction's location and its intended destination.

include/llvm/CodeGen/SelectionDAGNodes.h

@@ -549,6 +549,15 @@ public:
     return FoundNode;
   }
 
+  /// getFlaggedUser - If this node has a flag value with a user, return
+  /// the user (there is at most one). Otherwise return NULL.
+  SDNode *getFlaggedUser() const {
+    for (use_iterator UI = use_begin(), UE = use_end(); UI != UE; ++UI)
+      if (UI.getUse().get().getValueType() == MVT::Flag)
+        return *UI;
+    return 0;
+  }
+
   /// getNumValues - Return the number of values defined/returned by this
   /// operator.
   ///