#define LLVM_ANALYSIS_ALIAS_ANALYSIS_H
#include "llvm/Support/CallSite.h"
-#include "llvm/Pass.h"
+#include "llvm/Pass.h" // Need this for IncludeFile
namespace llvm {
class LoadInst;
class StoreInst;
class TargetData;
-class AnalysisUsage;
-class Pass;
class AliasAnalysis {
const TargetData *TD;
/// 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; }
//===--------------------------------------------------------------------===//
///
virtual void getMustAliases(Value *P, std::vector<Value*> &RetVals) {}
+ /// pointsToConstantMemory - If the specified pointer is known to point into
+ /// constant global memory, return true. This allows disambiguation of store
+ /// instructions from constant pointers.
+ ///
+ virtual bool pointsToConstantMemory(const Value *P) { return false; }
+
+ /// doesNotAccessMemory - If the specified function is known to never read or
+ /// write memory, return true. If the function only reads from known-constant
+ /// memory, it is also legal to return true. Functions that unwind the stack
+ /// are not legal for this predicate.
+ ///
+ /// Many optimizations (such as CSE and LICM) can be performed on calls to it,
+ /// without worrying about aliasing properties, and many functions have this
+ /// property (e.g. 'sin' and 'cos').
+ ///
+ /// This property corresponds to the GCC 'const' attribute.
+ ///
+ virtual bool doesNotAccessMemory(Function *F) { return false; }
+
+ /// onlyReadsMemory - If the specified function is known to only read from
+ /// non-volatile memory (or not access memory at all), return true. Functions
+ /// that unwind the stack are not legal for this predicate.
+ ///
+ /// This property allows many common optimizations to be performed in the
+ /// absence of interfering store instructions, such as CSE of strlen calls.
+ ///
+ /// This property corresponds to the GCC 'pure' attribute.
+ ///
+ virtual bool onlyReadsMemory(Function *F) { return doesNotAccessMemory(F); }
+
//===--------------------------------------------------------------------===//
/// Simple mod/ref information...
/// a particular call site modifies or reads the memory specified by the
/// pointer.
///
- virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size) {
- return ModRef;
- }
+ virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
/// 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.
+ /// the two calls refer to disjoint memory locations, Ref if CS1 reads memory
+ /// written by CS2, Mod if CS1 writes to memory read or written by CS2, or
+ /// ModRef if CS1 might read or write memory accessed by CS2.
///
- virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
- return ModRef;
- }
+ virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2);
+
+ /// hasNoModRefInfoForCalls - Return true if the analysis has no mod/ref
+ /// information for pairs of function calls (other than "pure" and "const"
+ /// functions). This can be used by clients to avoid many pointless queries.
+ /// Remember that if you override this and chain to another analysis, you must
+ /// make sure that it doesn't have mod/ref info either.
+ ///
+ virtual bool hasNoModRefInfoForCalls() const { return false; }
+
/// 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) {
+ 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) {
+ ModRefResult getModRefInfo(InvokeInst *I, Value *P, unsigned Size) {
return getModRefInfo(CallSite(I), P, Size);
}
ModRefResult getModRefInfo(Instruction *I, Value *P, unsigned Size) {