[llvm-commits] CVS: llvm/include/llvm/Analysis/AliasAnalysis.h
Chris Lattner
lattner at cs.uiuc.edu
Wed Feb 26 13:26:03 PST 2003
Changes in directory llvm/include/llvm/Analysis:
AliasAnalysis.h updated: 1.3 -> 1.4
---
Log message:
Checkin of new alias analysis interface:
* Takes into account the size of the memory reference to determine aliasing.
* Expose mod/ref information in a more consistent way
---
Diffs of the changes:
Index: llvm/include/llvm/Analysis/AliasAnalysis.h
diff -u llvm/include/llvm/Analysis/AliasAnalysis.h:1.3 llvm/include/llvm/Analysis/AliasAnalysis.h:1.4
--- llvm/include/llvm/Analysis/AliasAnalysis.h:1.3 Wed Nov 6 11:17:55 2002
+++ llvm/include/llvm/Analysis/AliasAnalysis.h Wed Feb 26 13:24:47 2003
@@ -2,24 +2,61 @@
//
// This file defines the generic AliasAnalysis interface, which is used as the
// common interface used by all clients of alias analysis information, and
-// implemented by all alias analysis implementations.
+// implemented by all alias analysis implementations. Mod/Ref information is
+// also captured by this interface.
//
// Implementations of this interface must implement the various virtual methods,
// which automatically provides functionality for the entire suite of client
// APIs.
//
+// This API represents memory as a (Pointer, Size) pair. The Pointer component
+// specifies the base memory address of the region, the Size specifies how large
+// of an area is being queried. If Size is 0, two pointers only alias if they
+// are exactly equal. If size is greater than zero, but small, the two pointers
+// alias if the areas pointed to overlap. If the size is very large (ie, ~0U),
+// then the two pointers alias if they may be pointing to components of the same
+// memory object. Pointers that point to two completely different objects in
+// memory never alias, regardless of the value of the Size component.
+//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_ALIAS_ANALYSIS_H
#define LLVM_ANALYSIS_ALIAS_ANALYSIS_H
-class Value;
-class CallInst;
-class InvokeInst;
-class BasicBlock;
-class Instruction;
+#include "llvm/Support/CallSite.h"
+class LoadInst;
+class StoreInst;
+class TargetData;
+class AnalysisUsage;
+class Pass;
+
+class AliasAnalysis {
+ const TargetData *TD;
+protected:
+ /// InitializeAliasAnalysis - Subclasses must call this method to initialize
+ /// the AliasAnalysis interface before any other methods are called. This is
+ /// typically called by the run* methods of these subclasses. This may be
+ /// called multiple times.
+ ///
+ void InitializeAliasAnalysis(Pass *P);
+
+ // getAnalysisUsage - All alias analysis implementations should invoke this
+ // directly (using AliasAnalysis::getAnalysisUsage(AU)) to make sure that
+ // TargetData is required by the pass.
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const;
+
+public:
+ AliasAnalysis() : TD(0) {}
+ virtual ~AliasAnalysis(); // We want to be subclassed
+
+ /// getTargetData - Every alias analysis implementation depends on the size of
+ /// data items in the current Target. This provides a uniform way to handle
+ /// it.
+ const TargetData &getTargetData() const { return *TD; }
-struct AliasAnalysis {
+ //===--------------------------------------------------------------------===//
+ /// Alias Queries...
+ ///
/// Alias analysis result - Either we know for sure that it does not alias, we
/// know for sure it must alias, or we don't know anything: The two pointers
@@ -27,29 +64,72 @@
/// if (AA.alias(P1, P2)) { ... }
/// to check to see if two pointers might alias.
///
- enum Result { NoAlias = 0, MayAlias = 1, MustAlias = 2 };
+ enum AliasResult { NoAlias = 0, MayAlias = 1, MustAlias = 2 };
/// alias - The main low level interface to the alias analysis implementation.
/// Returns a Result indicating whether the two pointers are aliased to each
/// other. This is the interface that must be implemented by specific alias
/// analysis implementations.
///
- virtual Result alias(const Value *V1, const Value *V2) = 0;
-
- /// canCallModify - Return a Result that indicates whether the specified
- /// function call can modify the memory location pointed to by Ptr.
- ///
- virtual Result canCallModify(const CallInst &CI, const Value *Ptr) = 0;
-
- /// canInvokeModify - Return a Result that indicates whether the specified
- /// function invoke can modify the memory location pointed to by Ptr.
- ///
- virtual Result canInvokeModify(const InvokeInst &I, const Value *Ptr) = 0;
+ virtual AliasResult alias(const Value *V1, unsigned V1Size,
+ const Value *V2, unsigned V2Size) {
+ return MayAlias;
+ }
+
+ //===--------------------------------------------------------------------===//
+ /// Simple mod/ref information...
+ ///
+
+ /// ModRefResult - Represent the result of a mod/ref query. Mod and Ref are
+ /// bits which may be or'd together.
+ ///
+ enum ModRefResult { NoModRef = 0, Ref = 1, Mod = 2, ModRef = 3 };
+
+ /// getModRefInfo - Return information about whether or not an instruction may
+ /// read or write memory specified by the pointer operand. An instruction
+ /// that doesn't read or write memory may be trivially LICM'd for example.
+
+ /// getModRefInfo (for call sites) - Return whether information about whether
+ /// a particular call site modifies or reads the memory specified by the
+ /// pointer.
+ ///
+ virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size) {
+ return ModRef;
+ }
+
+ /// getModRefInfo - Return information about whether two call sites may refer
+ /// to the same set of memory locations. This function returns NoModRef if
+ /// the two calls refer to disjoint memory locations, Ref if they both read
+ /// some of the same memory, Mod if they both write to some of the same
+ /// memory, and ModRef if they read and write to the same memory.
+ ///
+ virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
+ return ModRef;
+ }
+
+ /// Convenience functions...
+ ModRefResult getModRefInfo(LoadInst *L, Value *P, unsigned Size);
+ ModRefResult getModRefInfo(StoreInst*S, Value *P, unsigned Size);
+ ModRefResult getModRefInfo(CallInst *C, Value *P, unsigned Size) {
+ return getModRefInfo(CallSite(C), P, Size);
+ }
+ ModRefResult getModRefInfo(InvokeInst*I, Value *P, unsigned Size) {
+ return getModRefInfo(CallSite(I), P, Size);
+ }
+ ModRefResult getModRefInfo(Instruction *I, Value *P, unsigned Size) {
+ switch (I->getOpcode()) {
+ case Instruction::Load: return getModRefInfo((LoadInst*)I, P, Size);
+ case Instruction::Store: return getModRefInfo((StoreInst*)I, P, Size);
+ case Instruction::Call: return getModRefInfo((CallInst*)I, P, Size);
+ case Instruction::Invoke: return getModRefInfo((InvokeInst*)I, P, Size);
+ default: return NoModRef;
+ }
+ }
/// canBasicBlockModify - Return true if it is possible for execution of the
/// specified basic block to modify the value pointed to by Ptr.
///
- bool canBasicBlockModify(const BasicBlock &BB, const Value *Ptr);
+ bool canBasicBlockModify(const BasicBlock &BB, const Value *P, unsigned Size);
/// canInstructionRangeModify - Return true if it is possible for the
/// execution of the specified instructions to modify the value pointed to by
@@ -57,9 +137,7 @@
/// range of [I1,I2] INCLUSIVE. I1 and I2 must be in the same basic block.
///
bool canInstructionRangeModify(const Instruction &I1, const Instruction &I2,
- const Value *Ptr);
-
- virtual ~AliasAnalysis(); // We want to be subclassed
+ const Value *Ptr, unsigned Size);
};
#endif
More information about the llvm-commits
mailing list