Enhance the memdep interface so that users can tell the difference between a dependency which cannot be calculated and a path reaching the entry point of the function. This patch introduces isNonFuncLocal, which replaces isUnknown in some cases.

Patch by Xiaoyi Guo.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141896 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 48 insertions, 13 deletions

diff --git a/include/llvm/Analysis/MemoryDependenceAnalysis.h b/include/llvm/Analysis/MemoryDependenceAnalysis.h
index 34860e712f..e18d937f69 100644
--- a/include/llvm/Analysis/MemoryDependenceAnalysis.h
+++ b/include/llvm/Analysis/MemoryDependenceAnalysis.h
@@ -52,9 +52,6 @@ namespace llvm {
       ///   1. Loads are clobbered by may-alias stores.
       ///   2. Loads are considered clobbered by partially-aliased loads.  The
       ///      client may choose to analyze deeper into these cases.
-      ///
-      /// A dependence query on the first instruction of the entry block will
-      /// return a clobber(self) result.
       Clobber,
 
       /// Def - This is a dependence on the specified instruction which
@@ -76,11 +73,27 @@ namespace llvm {
       ///      operands to the calls are the same.
       Def,
       
+      /// Other - This marker indicates that the query has no known dependency
+      /// in the specified block.  More detailed state info is encoded in the
+      /// upper part of the pair (i.e. the Instruction*)
+      Other
+    };
+    /// If DepType is "Other", the upper part of the pair
+    /// (i.e. the Instruction* part) is instead used to encode more detailed
+    /// type information as follows
+    enum OtherType {
       /// NonLocal - This marker indicates that the query has no dependency in
       /// the specified block.  To find out more, the client should query other
       /// predecessor blocks.
-      NonLocal
+      NonLocal = 0x4,
+      /// NonFuncLocal - This marker indicates that the query has no
+      /// dependency in the specified function.
+      NonFuncLocal = 0x8,
+      /// Unknown - This marker indicates that the query dependency
+      /// is unknown.
+      Unknown = 0xc
     };
+
     typedef PointerIntPair<Instruction*, 2, DepType> PairTy;
     PairTy Value;
     explicit MemDepResult(PairTy V) : Value(V) {}
@@ -98,19 +111,21 @@ namespace llvm {
       return MemDepResult(PairTy(Inst, Clobber));
     }
     static MemDepResult getNonLocal() {
-      return MemDepResult(PairTy(0, NonLocal));
+      return MemDepResult(
+        PairTy(reinterpret_cast<Instruction*>(NonLocal), Other));
+    }
+    static MemDepResult getNonFuncLocal() {
+      return MemDepResult(
+        PairTy(reinterpret_cast<Instruction*>(NonFuncLocal), Other));
     }
     static MemDepResult getUnknown() {
-      return MemDepResult(PairTy(0, Clobber));
+      return MemDepResult(
+        PairTy(reinterpret_cast<Instruction*>(Unknown), Other));
     }
 
     /// isClobber - Return true if this MemDepResult represents a query that is
     /// a instruction clobber dependency.
-    bool isClobber() const { return Value.getInt() == Clobber && getInst(); }
-
-    /// isUnknown - Return true if this MemDepResult represents a query which
-    /// cannot and/or will not be computed.
-    bool isUnknown() const { return Value.getInt() == Clobber && !getInst(); }
+    bool isClobber() const { return Value.getInt() == Clobber; }
 
     /// isDef - Return true if this MemDepResult represents a query that is
     /// a instruction definition dependency.
@@ -119,11 +134,31 @@ namespace llvm {
     /// isNonLocal - Return true if this MemDepResult represents a query that
     /// is transparent to the start of the block, but where a non-local hasn't
     /// been done.
-    bool isNonLocal() const { return Value.getInt() == NonLocal; }
+    bool isNonLocal() const {
+      return Value.getInt() == Other
+        && Value.getPointer() == reinterpret_cast<Instruction*>(NonLocal);
+    }
+
+    /// isNonFuncLocal - Return true if this MemDepResult represents a query
+    /// that is transparent to the start of the function.
+    bool isNonFuncLocal() const {
+      return Value.getInt() == Other
+        && Value.getPointer() == reinterpret_cast<Instruction*>(NonFuncLocal);
+    }
     
+    /// isUnknown - Return true if this MemDepResult represents a query which
+    /// cannot and/or will not be computed.
+    bool isUnknown() const {
+      return Value.getInt() == Other
+        && Value.getPointer() == reinterpret_cast<Instruction*>(Unknown);
+    }
+
     /// getInst() - If this is a normal dependency, return the instruction that
     /// is depended on.  Otherwise, return null.
-    Instruction *getInst() const { return Value.getPointer(); }
+    Instruction *getInst() const {
+      if (Value.getInt() == Other) return NULL;
+      return Value.getPointer();
+    }
     
     bool operator==(const MemDepResult &M) const { return Value == M.Value; }
     bool operator!=(const MemDepResult &M) const { return Value != M.Value; }