Subzero: Initial O2 lowering

src/IceDefs.h

Index: src/IceDefs.h
diff --git a/src/IceDefs.h b/src/IceDefs.h
index 9870716d7b27391530adede5fffd58c53e9b7abe..4c616f832bb68c19cb67412c91483c6a91c297a4 100644
--- a/src/IceDefs.h
+++ b/src/IceDefs.h
@@ -50,6 +50,8 @@ class GlobalContext;
 class Inst;
 class InstPhi;
 class InstTarget;
+class LiveRange;
+class Liveness;
 class Operand;
 class TargetLowering;
 class Variable;
@@ -68,6 +70,23 @@ typedef std::vector<Constant *> ConstantList;
 // may be 64-bits wide) when we want to save space.
 typedef uint32_t SizeT;
 
+// InstNumberT is for holding an instruction number.  Instruction
+// numbers are used for representing Variable live ranges.
+typedef int32_t InstNumberT;
+
+enum LivenessMode {
+  // Basic version of live-range-end calculation.  Marks the last uses
+  // of variables based on dataflow analysis.  Records the set of
+  // live-in and live-out variables for each block.  Identifies and
+  // deletes dead instructions (primarily stores).
+  Liveness_Basic,
+
+  // In addition to Liveness_Basic, also calculate the complete
+  // live range for each variable in a form suitable for interference
+  // calculation and register allocation.
+  Liveness_Intervals
+};
+
 enum VerboseItem {
   IceV_None = 0,
   IceV_Instructions = 1 << 0,