Teach TargetRegisterInfo how to cram stack slot indexes in with the virtual and

physical register numbers.

This makes the hack used in LiveInterval official, and lets LiveInterval be
oblivious of stack slots.

The isPhysicalRegister() and isVirtualRegister() predicates don't know about
this, so when a variable may contain a stack slot, isStackSlot() should always
be tested first.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123128 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 30 insertions, 34 deletions

diff --git a/include/llvm/CodeGen/LiveInterval.h b/include/llvm/CodeGen/LiveInterval.h
index 192f07ec56..b2915cee97 100644
--- a/include/llvm/CodeGen/LiveInterval.h
+++ b/include/llvm/CodeGen/LiveInterval.h
@@ -205,8 +205,7 @@ namespace llvm {
     typedef SmallVector<LiveRange,4> Ranges;
     typedef SmallVector<VNInfo*,4> VNInfoList;
 
-    unsigned reg;        // the register or stack slot of this interval
-                         // if the top bits is set, it represents a stack slot.
+    const unsigned reg;  // the register or stack slot of this interval.
     float weight;        // weight of this interval
     Ranges ranges;       // the ranges in which this register is live
     VNInfoList valnos;   // value#'s
@@ -222,11 +221,8 @@ namespace llvm {
 
     };
 
-    LiveInterval(unsigned Reg, float Weight, bool IsSS = false)
-      : reg(Reg), weight(Weight) {
-      if (IsSS)
-        reg = reg | (1U << (sizeof(unsigned)*CHAR_BIT-1));
-    }
+    LiveInterval(unsigned Reg, float Weight)
+      : reg(Reg), weight(Weight) {}
 
     typedef Ranges::iterator iterator;
     iterator begin() { return ranges.begin(); }
@@ -275,19 +271,6 @@ namespace llvm {
       ranges.clear();
     }
 
-    /// isStackSlot - Return true if this is a stack slot interval.
-    ///
-    bool isStackSlot() const {
-      return reg & (1U << (sizeof(unsigned)*CHAR_BIT-1));
-    }
-
-    /// getStackSlotIndex - Return stack slot index if this is a stack slot
-    /// interval.
-    int getStackSlotIndex() const {
-      assert(isStackSlot() && "Interval is not a stack slot interval!");
-      return reg & ~(1U << (sizeof(unsigned)*CHAR_BIT-1));
-    }
-
     bool hasAtLeastOneValue() const { return !valnos.empty(); }
 
     bool containsOneValue() const { return valnos.size() == 1; }
diff --git a/include/llvm/CodeGen/LiveStackAnalysis.h b/include/llvm/CodeGen/LiveStackAnalysis.h
index 9310a30a4d..8a8dcaf572 100644
--- a/include/llvm/CodeGen/LiveStackAnalysis.h
+++ b/include/llvm/CodeGen/LiveStackAnalysis.h
@@ -52,19 +52,7 @@ namespace llvm {
 
     unsigned getNumIntervals() const { return (unsigned)S2IMap.size(); }
 
-    LiveInterval &getOrCreateInterval(int Slot, const TargetRegisterClass *RC) {
-      assert(Slot >= 0 && "Spill slot indice must be >= 0");
-      SS2IntervalMap::iterator I = S2IMap.find(Slot);
-      if (I == S2IMap.end()) {
-        I = S2IMap.insert(I,std::make_pair(Slot, LiveInterval(Slot,0.0F,true)));
-        S2RCMap.insert(std::make_pair(Slot, RC));
-      } else {
-        // Use the largest common subclass register class.
-        const TargetRegisterClass *OldRC = S2RCMap[Slot];
-        S2RCMap[Slot] = getCommonSubClass(OldRC, RC);
-      }
-      return I->second;
-    }
+    LiveInterval &getOrCreateInterval(int Slot, const TargetRegisterClass *RC);
 
     LiveInterval &getInterval(int Slot) {
       assert(Slot >= 0 && "Spill slot indice must be >= 0");
diff --git a/include/llvm/Target/TargetRegisterInfo.h b/include/llvm/Target/TargetRegisterInfo.h
index b8fa8a07dc..c2a973e0db 100644
--- a/include/llvm/Target/TargetRegisterInfo.h
+++ b/include/llvm/Target/TargetRegisterInfo.h
@@ -307,6 +307,31 @@ public:
     FirstVirtualRegister = 16384
   };
 
+  /// isStackSlot - Sometimes it is useful the be able to store a non-negative
+  /// frame index in a variable that normally holds a register. isStackSlot()
+  /// returns true if Reg is in the range used for stack slots.
+  ///
+  /// Note that isVirtualRegister() and isPhysicalRegister() may also return
+  /// true for such a value. In that case, isStackSlot() takes precedence.
+  ///
+  static bool isStackSlot(unsigned Reg) {
+    return Reg >= (1u << 31);
+  }
+
+  /// stackSlot2Index - Compute the frame index from a register value
+  /// representing a stack slot.
+  static int stackSlot2Index(unsigned Reg) {
+    assert(isStackSlot(Reg) && "Not a stack slot");
+    return int(Reg - (1u << 31));
+  }
+
+  /// index2StackSlot - Convert a non-negative frame index to a stack slot
+  /// register value.
+  static unsigned index2StackSlot(int FI) {
+    assert(FI >= 0 && "Cannot hold a negative frame index.");
+    return FI + (1u << 31);
+  }
+
   /// isPhysicalRegister - Return true if the specified register number is in
   /// the physical register namespace.
   static bool isPhysicalRegister(unsigned Reg) {
@@ -317,7 +342,7 @@ public:
   /// isVirtualRegister - Return true if the specified register number is in
   /// the virtual register namespace.
   static bool isVirtualRegister(unsigned Reg) {
-    assert(Reg && "this is not a register!");
+    assert(!isStackSlot(Reg) && "this is not a register!");
     return Reg >= FirstVirtualRegister;
   }