[llvm-commits] [llvm] r113329 - in /llvm/trunk: include/llvm/Analysis/AliasAnalysis.h lib/Analysis/AliasAnalysis.cpp lib/Analysis/BasicAliasAnalysis.cpp
Dan Gohman
gohman at apple.com
Tue Sep 7 18:32:20 PDT 2010
Author: djg
Date: Tue Sep 7 20:32:20 2010
New Revision: 113329
URL: http://llvm.org/viewvc/llvm-project?rev=113329&view=rev
Log:
Add a new experimental generalized dependence query interface to
AliasAnalysis, and some code for implementing the new query on top of
existing implementations by making standard alias and getModRefInfo
queries.
Modified:
llvm/trunk/include/llvm/Analysis/AliasAnalysis.h
llvm/trunk/lib/Analysis/AliasAnalysis.cpp
llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp
Modified: llvm/trunk/include/llvm/Analysis/AliasAnalysis.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/AliasAnalysis.h?rev=113329&r1=113328&r2=113329&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/AliasAnalysis.h (original)
+++ llvm/trunk/include/llvm/Analysis/AliasAnalysis.h Tue Sep 7 20:32:20 2010
@@ -278,6 +278,81 @@
ImmutableCallSite CS2);
//===--------------------------------------------------------------------===//
+ /// Dependence queries.
+ ///
+
+ /// DependenceResult - These are the return values for getDependence queries.
+ /// They are defined in terms of "memory", but they are also used to model
+ /// other side effects, such as I/O and volatility.
+ enum DependenceResult {
+ /// ReadThenRead - The instructions are ReadThenReadSome and the second
+ /// instruction reads from exactly the same memory read from by the first.
+ ReadThenRead,
+
+ /// ReadThenReadSome - The instructions are Independent, both are read-only,
+ /// and the second instruction reads from a subset of the memory read from
+ /// by the first.
+ ReadThenReadSome,
+
+ /// Independent - Neither instruction reads from or writes to memory written
+ /// to by the other. All enum values lower than this one are special cases
+ /// of Indepenent.
+ Independent,
+
+ /// WriteThenRead - The instructions are WriteThenReadSome and the second
+ /// instruction reads from exactly the same memory written by the first.
+ WriteThenRead,
+
+ /// WriteThenReadSome - The first instruction is write-only, the second
+ /// instruction is read-only, and the second only reads from memory
+ /// written to by the first.
+ WriteThenReadSome,
+
+ /// ReadThenWrite - The instructions are ReadThenWriteSome and the second
+ /// instruction writes to exactly the same memory read from by the first.
+ ReadThenWrite,
+
+ /// WriteThenWrite - The instructions are WriteThenWriteSome, and the
+ /// second instruction writes to exactly the same memory written to by
+ /// the first.
+ WriteThenWrite,
+
+ /// WriteSomeThenWrite - Both instructions are write-only, and the second
+ /// instruction writes to a superset of the memory written to by the first.
+ WriteSomeThenWrite,
+
+ /// Unknown - The relationship between the instructions cannot be
+ /// determined or does not fit into any of the cases defined here.
+ Unknown
+ };
+
+ /// DependenceQueryFlags - Flags for refining dependence queries.
+ enum DependenceQueryFlags {
+ Default = 0,
+ IgnoreLoads = 1,
+ IgnoreStores = 2
+ };
+
+ /// getDependence - Determine the dependence relationship between the
+ /// instructions. This does not include "register" dependencies; it just
+ /// considers memory references and other side effects.
+ /// WARNING: This is an experimental interface.
+ DependenceResult getDependence(const Instruction *First,
+ const Instruction *Second) {
+ return getDependence(First, Default, Second, Default);
+ }
+
+ /// getDependence - Determine the dependence relationship between the
+ /// instructions. This does not include "register" dependencies; it just
+ /// considers memory references and other side effects. This overload
+ /// accepts additional flags to refine the query.
+ /// WARNING: This is an experimental interface.
+ virtual DependenceResult getDependence(const Instruction *First,
+ DependenceQueryFlags FirstFlags,
+ const Instruction *Second,
+ DependenceQueryFlags SecondFlags);
+
+ //===--------------------------------------------------------------------===//
/// Higher level methods for querying mod/ref information.
///
@@ -322,6 +397,15 @@
copyValue(Old, New);
deleteValue(Old);
}
+
+protected:
+ /// getDependenceViaModRefInfo - Helper function for implementing getDependence
+ /// in implementations which already have getModRefInfo implementations.
+ DependenceResult getDependenceViaModRefInfo(const Instruction *First,
+ DependenceQueryFlags FirstFlags,
+ const Instruction *Second,
+ DependenceQueryFlags SecondFlags);
+
};
/// isNoAliasCall - Return true if this pointer is returned by a noalias
Modified: llvm/trunk/lib/Analysis/AliasAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/AliasAnalysis.cpp?rev=113329&r1=113328&r2=113329&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/AliasAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/AliasAnalysis.cpp Tue Sep 7 20:32:20 2010
@@ -188,6 +188,14 @@
return AA->getModRefBehavior(F);
}
+AliasAnalysis::DependenceResult
+AliasAnalysis::getDependence(const Instruction *First,
+ DependenceQueryFlags FirstFlags,
+ const Instruction *Second,
+ DependenceQueryFlags SecondFlags) {
+ assert(AA && "AA didn't call InitializeAliasAnalyais in its run method!");
+ return AA->getDependence(First, FirstFlags, Second, SecondFlags);
+}
//===----------------------------------------------------------------------===//
// AliasAnalysis non-virtual helper method implementation
@@ -245,6 +253,190 @@
return ModRef;
}
+AliasAnalysis::DependenceResult
+AliasAnalysis::getDependenceViaModRefInfo(const Instruction *First,
+ DependenceQueryFlags FirstFlags,
+ const Instruction *Second,
+ DependenceQueryFlags SecondFlags) {
+ if (const LoadInst *L = dyn_cast<LoadInst>(First)) {
+ // Be over-conservative with volatile for now.
+ if (L->isVolatile())
+ return Unknown;
+
+ // Forward this query to getModRefInfo.
+ switch (getModRefInfo(Second,
+ L->getPointerOperand(),
+ getTypeStoreSize(L->getType()))) {
+ case NoModRef:
+ // Second doesn't reference First's memory, so they're independent.
+ return Independent;
+
+ case Ref:
+ // Second only reads from the memory read from by First. If it
+ // also writes to any other memory, be conservative.
+ if (Second->mayWriteToMemory())
+ return Unknown;
+
+ // If it's loading the same size from the same address, we can
+ // give a more precise result.
+ if (const LoadInst *SecondL = dyn_cast<LoadInst>(Second)) {
+ unsigned LSize = getTypeStoreSize(L->getType());
+ unsigned SecondLSize = getTypeStoreSize(SecondL->getType());
+ if (alias(L->getPointerOperand(), LSize,
+ SecondL->getPointerOperand(), SecondLSize) ==
+ MustAlias) {
+ // If the loads are the same size, it's ReadThenRead.
+ if (LSize == SecondLSize)
+ return ReadThenRead;
+
+ // If the second load is smaller, it's only ReadThenReadSome.
+ if (LSize > SecondLSize)
+ return ReadThenReadSome;
+ }
+ }
+
+ // Otherwise it's just two loads.
+ return Independent;
+
+ case Mod:
+ // Second only writes to the memory read from by First. If it
+ // also reads from any other memory, be conservative.
+ if (Second->mayReadFromMemory())
+ return Unknown;
+
+ // If it's storing the same size to the same address, we can
+ // give a more precise result.
+ if (const StoreInst *SecondS = dyn_cast<StoreInst>(Second)) {
+ unsigned LSize = getTypeStoreSize(L->getType());
+ unsigned SecondSSize = getTypeStoreSize(SecondS->getType());
+ if (alias(L->getPointerOperand(), LSize,
+ SecondS->getPointerOperand(), SecondSSize) ==
+ MustAlias) {
+ // If the load and the store are the same size, it's ReadThenWrite.
+ if (LSize == SecondSSize)
+ return ReadThenWrite;
+ }
+ }
+
+ // Otherwise we don't know if it could be writing to other memory.
+ return Unknown;
+
+ case ModRef:
+ // Second reads and writes to the memory read from by First.
+ // We don't have a way to express that.
+ return Unknown;
+ }
+
+ } else if (const StoreInst *S = dyn_cast<StoreInst>(First)) {
+ // Be over-conservative with volatile for now.
+ if (S->isVolatile())
+ return Unknown;
+
+ // Forward this query to getModRefInfo.
+ switch (getModRefInfo(Second,
+ S->getPointerOperand(),
+ getTypeStoreSize(S->getValueOperand()->getType()))) {
+ case NoModRef:
+ // Second doesn't reference First's memory, so they're independent.
+ return Independent;
+
+ case Ref:
+ // Second only reads from the memory written to by First. If it
+ // also writes to any other memory, be conservative.
+ if (Second->mayWriteToMemory())
+ return Unknown;
+
+ // If it's loading the same size from the same address, we can
+ // give a more precise result.
+ if (const LoadInst *SecondL = dyn_cast<LoadInst>(Second)) {
+ unsigned SSize = getTypeStoreSize(S->getValueOperand()->getType());
+ unsigned SecondLSize = getTypeStoreSize(SecondL->getType());
+ if (alias(S->getPointerOperand(), SSize,
+ SecondL->getPointerOperand(), SecondLSize) ==
+ MustAlias) {
+ // If the store and the load are the same size, it's WriteThenRead.
+ if (SSize == SecondLSize)
+ return WriteThenRead;
+
+ // If the load is smaller, it's only WriteThenReadSome.
+ if (SSize > SecondLSize)
+ return WriteThenReadSome;
+ }
+ }
+
+ // Otherwise we don't know if it could be reading from other memory.
+ return Unknown;
+
+ case Mod:
+ // Second only writes to the memory written to by First. If it
+ // also reads from any other memory, be conservative.
+ if (Second->mayReadFromMemory())
+ return Unknown;
+
+ // If it's storing the same size to the same address, we can
+ // give a more precise result.
+ if (const StoreInst *SecondS = dyn_cast<StoreInst>(Second)) {
+ unsigned SSize = getTypeStoreSize(S->getValueOperand()->getType());
+ unsigned SecondSSize = getTypeStoreSize(SecondS->getType());
+ if (alias(S->getPointerOperand(), SSize,
+ SecondS->getPointerOperand(), SecondSSize) ==
+ MustAlias) {
+ // If the stores are the same size, it's WriteThenWrite.
+ if (SSize == SecondSSize)
+ return WriteThenWrite;
+
+ // If the second store is larger, it's only WriteSomeThenWrite.
+ if (SSize < SecondSSize)
+ return WriteSomeThenWrite;
+ }
+ }
+
+ // Otherwise we don't know if it could be writing to other memory.
+ return Unknown;
+
+ case ModRef:
+ // Second reads and writes to the memory written to by First.
+ // We don't have a way to express that.
+ return Unknown;
+ }
+
+ } else if (const VAArgInst *V = dyn_cast<VAArgInst>(First)) {
+ // Forward this query to getModRefInfo.
+ if (getModRefInfo(Second, V->getOperand(0), UnknownSize) == NoModRef)
+ // Second doesn't reference First's memory, so they're independent.
+ return Independent;
+
+ } else if (ImmutableCallSite FirstCS = cast<Value>(First)) {
+ // If both instructions are calls/invokes we can use the two-callsite
+ // form of getModRefInfo.
+ if (ImmutableCallSite SecondCS = cast<Value>(Second))
+ // getModRefInfo's arguments are backwards from intuition.
+ switch (getModRefInfo(SecondCS, FirstCS)) {
+ case NoModRef:
+ // Second doesn't reference First's memory, so they're independent.
+ return Independent;
+
+ case Ref:
+ // If they're both read-only, there's no dependence.
+ if (FirstCS.onlyReadsMemory() && SecondCS.onlyReadsMemory())
+ return Independent;
+
+ // Otherwise it's not obvious what we can do here.
+ return Unknown;
+
+ case Mod:
+ // It's not obvious what we can do here.
+ return Unknown;
+
+ case ModRef:
+ // I know, right?
+ return Unknown;
+ }
+ }
+
+ // For anything else, be conservative.
+ return Unknown;
+}
AliasAnalysis::ModRefBehavior
AliasAnalysis::getIntrinsicModRefBehavior(unsigned iid) {
Modified: llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp?rev=113329&r1=113328&r2=113329&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp Tue Sep 7 20:32:20 2010
@@ -171,6 +171,13 @@
return ModRef;
}
+ virtual DependenceResult getDependence(const Instruction *First,
+ DependenceQueryFlags FirstFlags,
+ const Instruction *Second,
+ DependenceQueryFlags SecondFlags) {
+ return Unknown;
+ }
+
virtual void deleteValue(Value *V) {}
virtual void copyValue(Value *From, Value *To) {}
@@ -523,6 +530,11 @@
/// For use when the call site is not known.
virtual ModRefBehavior getModRefBehavior(const Function *F);
+ virtual DependenceResult getDependence(const Instruction *First,
+ DependenceQueryFlags FirstFlags,
+ const Instruction *Second,
+ DependenceQueryFlags SecondFlags);
+
/// getAdjustedAnalysisPointer - This method is used when a pass implements
/// an analysis interface through multiple inheritance. If needed, it
/// should override this to adjust the this pointer as needed for the
@@ -734,6 +746,14 @@
return AliasAnalysis::getModRefInfo(CS, P, Size);
}
+AliasAnalysis::DependenceResult
+BasicAliasAnalysis::getDependence(const Instruction *First,
+ DependenceQueryFlags FirstFlags,
+ const Instruction *Second,
+ DependenceQueryFlags SecondFlags) {
+ // We don't have anything special to say yet.
+ return getDependenceViaModRefInfo(First, FirstFlags, Second, SecondFlags);
+}
/// aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP instruction
/// against another pointer. We know that V1 is a GEP, but we don't know
More information about the llvm-commits
mailing list