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-rw-r--r--contrib/llvm/lib/Analysis/BasicAliasAnalysis.cpp170
1 files changed, 132 insertions, 38 deletions
diff --git a/contrib/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/contrib/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index 1d028c27b8c3..4bb93ee88a49 100644
--- a/contrib/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/contrib/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -29,7 +29,7 @@
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/ValueTracking.h"
-#include "llvm/Target/TargetData.h"
+#include "llvm/DataLayout.h"
#include "llvm/Target/TargetLibraryInfo.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
@@ -58,12 +58,12 @@ static bool isNonEscapingLocalObject(const Value *V) {
// then it has not escaped before entering the function. Check if it escapes
// inside the function.
if (const Argument *A = dyn_cast<Argument>(V))
- if (A->hasByValAttr() || A->hasNoAliasAttr()) {
- // Don't bother analyzing arguments already known not to escape.
- if (A->hasNoCaptureAttr())
- return true;
+ if (A->hasByValAttr() || A->hasNoAliasAttr())
+ // Note even if the argument is marked nocapture we still need to check
+ // for copies made inside the function. The nocapture attribute only
+ // specifies that there are no copies made that outlive the function.
return !PointerMayBeCaptured(V, false, /*StoreCaptures=*/true);
- }
+
return false;
}
@@ -84,10 +84,11 @@ static bool isEscapeSource(const Value *V) {
/// getObjectSize - Return the size of the object specified by V, or
/// UnknownSize if unknown.
-static uint64_t getObjectSize(const Value *V, const TargetData &TD,
+static uint64_t getObjectSize(const Value *V, const DataLayout &TD,
+ const TargetLibraryInfo &TLI,
bool RoundToAlign = false) {
uint64_t Size;
- if (getObjectSize(V, Size, &TD, RoundToAlign))
+ if (getObjectSize(V, Size, &TD, &TLI, RoundToAlign))
return Size;
return AliasAnalysis::UnknownSize;
}
@@ -95,10 +96,11 @@ static uint64_t getObjectSize(const Value *V, const TargetData &TD,
/// isObjectSmallerThan - Return true if we can prove that the object specified
/// by V is smaller than Size.
static bool isObjectSmallerThan(const Value *V, uint64_t Size,
- const TargetData &TD) {
+ const DataLayout &TD,
+ const TargetLibraryInfo &TLI) {
// This function needs to use the aligned object size because we allow
// reads a bit past the end given sufficient alignment.
- uint64_t ObjectSize = getObjectSize(V, TD, /*RoundToAlign*/true);
+ uint64_t ObjectSize = getObjectSize(V, TD, TLI, /*RoundToAlign*/true);
return ObjectSize != AliasAnalysis::UnknownSize && ObjectSize < Size;
}
@@ -106,8 +108,8 @@ static bool isObjectSmallerThan(const Value *V, uint64_t Size,
/// isObjectSize - Return true if we can prove that the object specified
/// by V has size Size.
static bool isObjectSize(const Value *V, uint64_t Size,
- const TargetData &TD) {
- uint64_t ObjectSize = getObjectSize(V, TD);
+ const DataLayout &TD, const TargetLibraryInfo &TLI) {
+ uint64_t ObjectSize = getObjectSize(V, TD, TLI);
return ObjectSize != AliasAnalysis::UnknownSize && ObjectSize == Size;
}
@@ -126,6 +128,15 @@ namespace {
const Value *V;
ExtensionKind Extension;
int64_t Scale;
+
+ bool operator==(const VariableGEPIndex &Other) const {
+ return V == Other.V && Extension == Other.Extension &&
+ Scale == Other.Scale;
+ }
+
+ bool operator!=(const VariableGEPIndex &Other) const {
+ return !operator==(Other);
+ }
};
}
@@ -140,7 +151,7 @@ namespace {
/// represented in the result.
static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset,
ExtensionKind &Extension,
- const TargetData &TD, unsigned Depth) {
+ const DataLayout &TD, unsigned Depth) {
assert(V->getType()->isIntegerTy() && "Not an integer value");
// Limit our recursion depth.
@@ -215,14 +226,14 @@ static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset,
/// specified amount, but which may have other unrepresented high bits. As such,
/// the gep cannot necessarily be reconstructed from its decomposed form.
///
-/// When TargetData is around, this function is capable of analyzing everything
+/// When DataLayout is around, this function is capable of analyzing everything
/// that GetUnderlyingObject can look through. When not, it just looks
/// through pointer casts.
///
static const Value *
DecomposeGEPExpression(const Value *V, int64_t &BaseOffs,
SmallVectorImpl<VariableGEPIndex> &VarIndices,
- const TargetData *TD) {
+ const DataLayout *TD) {
// Limit recursion depth to limit compile time in crazy cases.
unsigned MaxLookup = 6;
@@ -266,7 +277,7 @@ DecomposeGEPExpression(const Value *V, int64_t &BaseOffs,
->getElementType()->isSized())
return V;
- // If we are lacking TargetData information, we can't compute the offets of
+ // If we are lacking DataLayout information, we can't compute the offets of
// elements computed by GEPs. However, we can handle bitcast equivalent
// GEPs.
if (TD == 0) {
@@ -417,13 +428,7 @@ namespace {
/// BasicAliasAnalysis - This is the primary alias analysis implementation.
struct BasicAliasAnalysis : public ImmutablePass, public AliasAnalysis {
static char ID; // Class identification, replacement for typeinfo
- BasicAliasAnalysis() : ImmutablePass(ID),
- // AliasCache rarely has more than 1 or 2 elements,
- // so start it off fairly small so that clear()
- // doesn't have to tromp through 64 (the default)
- // elements on each alias query. This really wants
- // something like a SmallDenseMap.
- AliasCache(8) {
+ BasicAliasAnalysis() : ImmutablePass(ID) {
initializeBasicAliasAnalysisPass(*PassRegistry::getPassRegistry());
}
@@ -443,7 +448,11 @@ namespace {
"BasicAliasAnalysis doesn't support interprocedural queries.");
AliasResult Alias = aliasCheck(LocA.Ptr, LocA.Size, LocA.TBAATag,
LocB.Ptr, LocB.Size, LocB.TBAATag);
- AliasCache.clear();
+ // AliasCache rarely has more than 1 or 2 elements, always use
+ // shrink_and_clear so it quickly returns to the inline capacity of the
+ // SmallDenseMap if it ever grows larger.
+ // FIXME: This should really be shrink_to_inline_capacity_and_clear().
+ AliasCache.shrink_and_clear();
return Alias;
}
@@ -481,7 +490,7 @@ namespace {
private:
// AliasCache - Track alias queries to guard against recursion.
typedef std::pair<Location, Location> LocPair;
- typedef DenseMap<LocPair, AliasResult> AliasCacheTy;
+ typedef SmallDenseMap<LocPair, AliasResult, 8> AliasCacheTy;
AliasCacheTy AliasCache;
// Visited - Track instructions visited by pointsToConstantMemory.
@@ -490,6 +499,7 @@ namespace {
// aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP
// instruction against another.
AliasResult aliasGEP(const GEPOperator *V1, uint64_t V1Size,
+ const MDNode *V1TBAAInfo,
const Value *V2, uint64_t V2Size,
const MDNode *V2TBAAInfo,
const Value *UnderlyingV1, const Value *UnderlyingV2);
@@ -807,6 +817,21 @@ BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS,
return ModRefResult(AliasAnalysis::getModRefInfo(CS, Loc) & Min);
}
+static bool areVarIndicesEqual(SmallVector<VariableGEPIndex, 4> &Indices1,
+ SmallVector<VariableGEPIndex, 4> &Indices2) {
+ unsigned Size1 = Indices1.size();
+ unsigned Size2 = Indices2.size();
+
+ if (Size1 != Size2)
+ return false;
+
+ for (unsigned I = 0; I != Size1; ++I)
+ if (Indices1[I] != Indices2[I])
+ return false;
+
+ return true;
+}
+
/// 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
/// anything about V2. UnderlyingV1 is GetUnderlyingObject(GEP1, TD),
@@ -814,6 +839,7 @@ BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS,
///
AliasAnalysis::AliasResult
BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size,
+ const MDNode *V1TBAAInfo,
const Value *V2, uint64_t V2Size,
const MDNode *V2TBAAInfo,
const Value *UnderlyingV1,
@@ -821,9 +847,41 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size,
int64_t GEP1BaseOffset;
SmallVector<VariableGEPIndex, 4> GEP1VariableIndices;
- // If we have two gep instructions with must-alias'ing base pointers, figure
- // out if the indexes to the GEP tell us anything about the derived pointer.
+ // If we have two gep instructions with must-alias or not-alias'ing base
+ // pointers, figure out if the indexes to the GEP tell us anything about the
+ // derived pointer.
if (const GEPOperator *GEP2 = dyn_cast<GEPOperator>(V2)) {
+ // Check for geps of non-aliasing underlying pointers where the offsets are
+ // identical.
+ if (V1Size == V2Size) {
+ // Do the base pointers alias assuming type and size.
+ AliasResult PreciseBaseAlias = aliasCheck(UnderlyingV1, V1Size,
+ V1TBAAInfo, UnderlyingV2,
+ V2Size, V2TBAAInfo);
+ if (PreciseBaseAlias == NoAlias) {
+ // See if the computed offset from the common pointer tells us about the
+ // relation of the resulting pointer.
+ int64_t GEP2BaseOffset;
+ SmallVector<VariableGEPIndex, 4> GEP2VariableIndices;
+ const Value *GEP2BasePtr =
+ DecomposeGEPExpression(GEP2, GEP2BaseOffset, GEP2VariableIndices, TD);
+ const Value *GEP1BasePtr =
+ DecomposeGEPExpression(GEP1, GEP1BaseOffset, GEP1VariableIndices, TD);
+ // DecomposeGEPExpression and GetUnderlyingObject should return the
+ // same result except when DecomposeGEPExpression has no DataLayout.
+ if (GEP1BasePtr != UnderlyingV1 || GEP2BasePtr != UnderlyingV2) {
+ assert(TD == 0 &&
+ "DecomposeGEPExpression and GetUnderlyingObject disagree!");
+ return MayAlias;
+ }
+ // Same offsets.
+ if (GEP1BaseOffset == GEP2BaseOffset &&
+ areVarIndicesEqual(GEP1VariableIndices, GEP2VariableIndices))
+ return NoAlias;
+ GEP1VariableIndices.clear();
+ }
+ }
+
// Do the base pointers alias?
AliasResult BaseAlias = aliasCheck(UnderlyingV1, UnknownSize, 0,
UnderlyingV2, UnknownSize, 0);
@@ -843,9 +901,8 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size,
const Value *GEP2BasePtr =
DecomposeGEPExpression(GEP2, GEP2BaseOffset, GEP2VariableIndices, TD);
- // If DecomposeGEPExpression isn't able to look all the way through the
- // addressing operation, we must not have TD and this is too complex for us
- // to handle without it.
+ // DecomposeGEPExpression and GetUnderlyingObject should return the
+ // same result except when DecomposeGEPExpression has no DataLayout.
if (GEP1BasePtr != UnderlyingV1 || GEP2BasePtr != UnderlyingV2) {
assert(TD == 0 &&
"DecomposeGEPExpression and GetUnderlyingObject disagree!");
@@ -879,9 +936,8 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size,
const Value *GEP1BasePtr =
DecomposeGEPExpression(GEP1, GEP1BaseOffset, GEP1VariableIndices, TD);
- // If DecomposeGEPExpression isn't able to look all the way through the
- // addressing operation, we must not have TD and this is too complex for us
- // to handle without it.
+ // DecomposeGEPExpression and GetUnderlyingObject should return the
+ // same result except when DecomposeGEPExpression has no DataLayout.
if (GEP1BasePtr != UnderlyingV1) {
assert(TD == 0 &&
"DecomposeGEPExpression and GetUnderlyingObject disagree!");
@@ -1004,12 +1060,42 @@ BasicAliasAnalysis::aliasPHI(const PHINode *PN, uint64_t PNSize,
// on corresponding edges.
if (const PHINode *PN2 = dyn_cast<PHINode>(V2))
if (PN2->getParent() == PN->getParent()) {
+ LocPair Locs(Location(PN, PNSize, PNTBAAInfo),
+ Location(V2, V2Size, V2TBAAInfo));
+ if (PN > V2)
+ std::swap(Locs.first, Locs.second);
+
AliasResult Alias =
aliasCheck(PN->getIncomingValue(0), PNSize, PNTBAAInfo,
PN2->getIncomingValueForBlock(PN->getIncomingBlock(0)),
V2Size, V2TBAAInfo);
if (Alias == MayAlias)
return MayAlias;
+
+ // If the first source of the PHI nodes NoAlias and the other inputs are
+ // the PHI node itself through some amount of recursion this does not add
+ // any new information so just return NoAlias.
+ // bb:
+ // ptr = ptr2 + 1
+ // loop:
+ // ptr_phi = phi [bb, ptr], [loop, ptr_plus_one]
+ // ptr2_phi = phi [bb, ptr2], [loop, ptr2_plus_one]
+ // ...
+ // ptr_plus_one = gep ptr_phi, 1
+ // ptr2_plus_one = gep ptr2_phi, 1
+ // We assume for the recursion that the the phis (ptr_phi, ptr2_phi) do
+ // not alias each other.
+ bool ArePhisAssumedNoAlias = false;
+ AliasResult OrigAliasResult = NoAlias;
+ if (Alias == NoAlias) {
+ // Pretend the phis do not alias.
+ assert(AliasCache.count(Locs) &&
+ "There must exist an entry for the phi node");
+ OrigAliasResult = AliasCache[Locs];
+ AliasCache[Locs] = NoAlias;
+ ArePhisAssumedNoAlias = true;
+ }
+
for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) {
AliasResult ThisAlias =
aliasCheck(PN->getIncomingValue(i), PNSize, PNTBAAInfo,
@@ -1019,6 +1105,11 @@ BasicAliasAnalysis::aliasPHI(const PHINode *PN, uint64_t PNSize,
if (Alias == MayAlias)
break;
}
+
+ // Reset if speculation failed.
+ if (ArePhisAssumedNoAlias && Alias != NoAlias)
+ AliasCache[Locs] = OrigAliasResult;
+
return Alias;
}
@@ -1133,8 +1224,8 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, uint64_t V1Size,
// If the size of one access is larger than the entire object on the other
// side, then we know such behavior is undefined and can assume no alias.
if (TD)
- if ((V1Size != UnknownSize && isObjectSmallerThan(O2, V1Size, *TD)) ||
- (V2Size != UnknownSize && isObjectSmallerThan(O1, V2Size, *TD)))
+ if ((V1Size != UnknownSize && isObjectSmallerThan(O2, V1Size, *TD, *TLI)) ||
+ (V2Size != UnknownSize && isObjectSmallerThan(O1, V2Size, *TD, *TLI)))
return NoAlias;
// Check the cache before climbing up use-def chains. This also terminates
@@ -1154,15 +1245,17 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, uint64_t V1Size,
std::swap(V1, V2);
std::swap(V1Size, V2Size);
std::swap(O1, O2);
+ std::swap(V1TBAAInfo, V2TBAAInfo);
}
if (const GEPOperator *GV1 = dyn_cast<GEPOperator>(V1)) {
- AliasResult Result = aliasGEP(GV1, V1Size, V2, V2Size, V2TBAAInfo, O1, O2);
+ AliasResult Result = aliasGEP(GV1, V1Size, V1TBAAInfo, V2, V2Size, V2TBAAInfo, O1, O2);
if (Result != MayAlias) return AliasCache[Locs] = Result;
}
if (isa<PHINode>(V2) && !isa<PHINode>(V1)) {
std::swap(V1, V2);
std::swap(V1Size, V2Size);
+ std::swap(V1TBAAInfo, V2TBAAInfo);
}
if (const PHINode *PN = dyn_cast<PHINode>(V1)) {
AliasResult Result = aliasPHI(PN, V1Size, V1TBAAInfo,
@@ -1173,6 +1266,7 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, uint64_t V1Size,
if (isa<SelectInst>(V2) && !isa<SelectInst>(V1)) {
std::swap(V1, V2);
std::swap(V1Size, V2Size);
+ std::swap(V1TBAAInfo, V2TBAAInfo);
}
if (const SelectInst *S1 = dyn_cast<SelectInst>(V1)) {
AliasResult Result = aliasSelect(S1, V1Size, V1TBAAInfo,
@@ -1184,8 +1278,8 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, uint64_t V1Size,
// accesses is accessing the entire object, then the accesses must
// overlap in some way.
if (TD && O1 == O2)
- if ((V1Size != UnknownSize && isObjectSize(O1, V1Size, *TD)) ||
- (V2Size != UnknownSize && isObjectSize(O2, V2Size, *TD)))
+ if ((V1Size != UnknownSize && isObjectSize(O1, V1Size, *TD, *TLI)) ||
+ (V2Size != UnknownSize && isObjectSize(O2, V2Size, *TD, *TLI)))
return AliasCache[Locs] = PartialAlias;
AliasResult Result =
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-23 13:05:15 +0000