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-rw-r--r--lib/Analysis/AliasAnalysis.cpp95
1 files changed, 78 insertions, 17 deletions
diff --git a/lib/Analysis/AliasAnalysis.cpp b/lib/Analysis/AliasAnalysis.cpp
index dd2db1e5b27b..55df66714178 100644
--- a/lib/Analysis/AliasAnalysis.cpp
+++ b/lib/Analysis/AliasAnalysis.cpp
@@ -133,9 +133,9 @@ ModRefInfo AAResults::getArgModRefInfo(ImmutableCallSite CS, unsigned ArgIdx) {
}
ModRefInfo AAResults::getModRefInfo(Instruction *I, ImmutableCallSite Call) {
- // We may have two calls
+ // We may have two calls.
if (auto CS = ImmutableCallSite(I)) {
- // Check if the two calls modify the same memory
+ // Check if the two calls modify the same memory.
return getModRefInfo(CS, Call);
} else if (I->isFenceLike()) {
// If this is a fence, just return ModRef.
@@ -179,6 +179,7 @@ ModRefInfo AAResults::getModRefInfo(ImmutableCallSite CS,
if (onlyAccessesArgPointees(MRB) || onlyAccessesInaccessibleOrArgMem(MRB)) {
bool DoesAlias = false;
+ bool IsMustAlias = true;
ModRefInfo AllArgsMask = ModRefInfo::NoModRef;
if (doesAccessArgPointees(MRB)) {
for (auto AI = CS.arg_begin(), AE = CS.arg_end(); AI != AE; ++AI) {
@@ -193,6 +194,8 @@ ModRefInfo AAResults::getModRefInfo(ImmutableCallSite CS,
DoesAlias = true;
AllArgsMask = unionModRef(AllArgsMask, ArgMask);
}
+ // Conservatively clear IsMustAlias unless only MustAlias is found.
+ IsMustAlias &= (ArgAlias == MustAlias);
}
}
// Return NoModRef if no alias found with any argument.
@@ -200,6 +203,8 @@ ModRefInfo AAResults::getModRefInfo(ImmutableCallSite CS,
return ModRefInfo::NoModRef;
// Logical & between other AA analyses and argument analysis.
Result = intersectModRef(Result, AllArgsMask);
+ // If only MustAlias found above, set Must bit.
+ Result = IsMustAlias ? setMust(Result) : clearMust(Result);
}
// If Loc is a constant memory location, the call definitely could not
@@ -251,6 +256,7 @@ ModRefInfo AAResults::getModRefInfo(ImmutableCallSite CS1,
if (onlyAccessesArgPointees(CS2B)) {
ModRefInfo R = ModRefInfo::NoModRef;
if (doesAccessArgPointees(CS2B)) {
+ bool IsMustAlias = true;
for (auto I = CS2.arg_begin(), E = CS2.arg_end(); I != E; ++I) {
const Value *Arg = *I;
if (!Arg->getType()->isPointerTy())
@@ -274,10 +280,19 @@ ModRefInfo AAResults::getModRefInfo(ImmutableCallSite CS1,
ModRefInfo ModRefCS1 = getModRefInfo(CS1, CS2ArgLoc);
ArgMask = intersectModRef(ArgMask, ModRefCS1);
+ // Conservatively clear IsMustAlias unless only MustAlias is found.
+ IsMustAlias &= isMustSet(ModRefCS1);
+
R = intersectModRef(unionModRef(R, ArgMask), Result);
- if (R == Result)
+ if (R == Result) {
+ // On early exit, not all args were checked, cannot set Must.
+ if (I + 1 != E)
+ IsMustAlias = false;
break;
+ }
}
+ // If Alias found and only MustAlias found above, set Must bit.
+ R = IsMustAlias ? setMust(R) : clearMust(R);
}
return R;
}
@@ -287,6 +302,7 @@ ModRefInfo AAResults::getModRefInfo(ImmutableCallSite CS1,
if (onlyAccessesArgPointees(CS1B)) {
ModRefInfo R = ModRefInfo::NoModRef;
if (doesAccessArgPointees(CS1B)) {
+ bool IsMustAlias = true;
for (auto I = CS1.arg_begin(), E = CS1.arg_end(); I != E; ++I) {
const Value *Arg = *I;
if (!Arg->getType()->isPointerTy())
@@ -303,9 +319,18 @@ ModRefInfo AAResults::getModRefInfo(ImmutableCallSite CS1,
(isRefSet(ArgModRefCS1) && isModSet(ModRefCS2)))
R = intersectModRef(unionModRef(R, ArgModRefCS1), Result);
- if (R == Result)
+ // Conservatively clear IsMustAlias unless only MustAlias is found.
+ IsMustAlias &= isMustSet(ModRefCS2);
+
+ if (R == Result) {
+ // On early exit, not all args were checked, cannot set Must.
+ if (I + 1 != E)
+ IsMustAlias = false;
break;
+ }
}
+ // If Alias found and only MustAlias found above, set Must bit.
+ R = IsMustAlias ? setMust(R) : clearMust(R);
}
return R;
}
@@ -353,9 +378,13 @@ ModRefInfo AAResults::getModRefInfo(const LoadInst *L,
// If the load address doesn't alias the given address, it doesn't read
// or write the specified memory.
- if (Loc.Ptr && !alias(MemoryLocation::get(L), Loc))
- return ModRefInfo::NoModRef;
-
+ if (Loc.Ptr) {
+ AliasResult AR = alias(MemoryLocation::get(L), Loc);
+ if (AR == NoAlias)
+ return ModRefInfo::NoModRef;
+ if (AR == MustAlias)
+ return ModRefInfo::MustRef;
+ }
// Otherwise, a load just reads.
return ModRefInfo::Ref;
}
@@ -367,15 +396,20 @@ ModRefInfo AAResults::getModRefInfo(const StoreInst *S,
return ModRefInfo::ModRef;
if (Loc.Ptr) {
+ AliasResult AR = alias(MemoryLocation::get(S), Loc);
// If the store address cannot alias the pointer in question, then the
// specified memory cannot be modified by the store.
- if (!alias(MemoryLocation::get(S), Loc))
+ if (AR == NoAlias)
return ModRefInfo::NoModRef;
// If the pointer is a pointer to constant memory, then it could not have
// been modified by this store.
if (pointsToConstantMemory(Loc))
return ModRefInfo::NoModRef;
+
+ // If the store address aliases the pointer as must alias, set Must.
+ if (AR == MustAlias)
+ return ModRefInfo::MustMod;
}
// Otherwise, a store just writes.
@@ -393,15 +427,20 @@ ModRefInfo AAResults::getModRefInfo(const FenceInst *S, const MemoryLocation &Lo
ModRefInfo AAResults::getModRefInfo(const VAArgInst *V,
const MemoryLocation &Loc) {
if (Loc.Ptr) {
+ AliasResult AR = alias(MemoryLocation::get(V), Loc);
// If the va_arg address cannot alias the pointer in question, then the
// specified memory cannot be accessed by the va_arg.
- if (!alias(MemoryLocation::get(V), Loc))
+ if (AR == NoAlias)
return ModRefInfo::NoModRef;
// If the pointer is a pointer to constant memory, then it could not have
// been modified by this va_arg.
if (pointsToConstantMemory(Loc))
return ModRefInfo::NoModRef;
+
+ // If the va_arg aliases the pointer as must alias, set Must.
+ if (AR == MustAlias)
+ return ModRefInfo::MustModRef;
}
// Otherwise, a va_arg reads and writes.
@@ -440,9 +479,17 @@ ModRefInfo AAResults::getModRefInfo(const AtomicCmpXchgInst *CX,
if (isStrongerThanMonotonic(CX->getSuccessOrdering()))
return ModRefInfo::ModRef;
- // If the cmpxchg address does not alias the location, it does not access it.
- if (Loc.Ptr && !alias(MemoryLocation::get(CX), Loc))
- return ModRefInfo::NoModRef;
+ if (Loc.Ptr) {
+ AliasResult AR = alias(MemoryLocation::get(CX), Loc);
+ // If the cmpxchg address does not alias the location, it does not access
+ // it.
+ if (AR == NoAlias)
+ return ModRefInfo::NoModRef;
+
+ // If the cmpxchg address aliases the pointer as must alias, set Must.
+ if (AR == MustAlias)
+ return ModRefInfo::MustModRef;
+ }
return ModRefInfo::ModRef;
}
@@ -453,9 +500,17 @@ ModRefInfo AAResults::getModRefInfo(const AtomicRMWInst *RMW,
if (isStrongerThanMonotonic(RMW->getOrdering()))
return ModRefInfo::ModRef;
- // If the atomicrmw address does not alias the location, it does not access it.
- if (Loc.Ptr && !alias(MemoryLocation::get(RMW), Loc))
- return ModRefInfo::NoModRef;
+ if (Loc.Ptr) {
+ AliasResult AR = alias(MemoryLocation::get(RMW), Loc);
+ // If the atomicrmw address does not alias the location, it does not access
+ // it.
+ if (AR == NoAlias)
+ return ModRefInfo::NoModRef;
+
+ // If the atomicrmw address aliases the pointer as must alias, set Must.
+ if (AR == MustAlias)
+ return ModRefInfo::MustModRef;
+ }
return ModRefInfo::ModRef;
}
@@ -493,6 +548,8 @@ ModRefInfo AAResults::callCapturesBefore(const Instruction *I,
unsigned ArgNo = 0;
ModRefInfo R = ModRefInfo::NoModRef;
+ bool MustAlias = true;
+ // Set flag only if no May found and all operands processed.
for (auto CI = CS.data_operands_begin(), CE = CS.data_operands_end();
CI != CE; ++CI, ++ArgNo) {
// Only look at the no-capture or byval pointer arguments. If this
@@ -503,11 +560,14 @@ ModRefInfo AAResults::callCapturesBefore(const Instruction *I,
ArgNo < CS.getNumArgOperands() && !CS.isByValArgument(ArgNo)))
continue;
+ AliasResult AR = alias(MemoryLocation(*CI), MemoryLocation(Object));
// If this is a no-capture pointer argument, see if we can tell that it
// is impossible to alias the pointer we're checking. If not, we have to
// assume that the call could touch the pointer, even though it doesn't
// escape.
- if (isNoAlias(MemoryLocation(*CI), MemoryLocation(Object)))
+ if (AR != MustAlias)
+ MustAlias = false;
+ if (AR == NoAlias)
continue;
if (CS.doesNotAccessMemory(ArgNo))
continue;
@@ -515,9 +575,10 @@ ModRefInfo AAResults::callCapturesBefore(const Instruction *I,
R = ModRefInfo::Ref;
continue;
}
+ // Not returning MustModRef since we have not seen all the arguments.
return ModRefInfo::ModRef;
}
- return R;
+ return MustAlias ? setMust(R) : clearMust(R);
}
/// canBasicBlockModify - Return true if it is possible for execution of the
generated by cgit v1.2.3 (git 2.25.1) at 2025-11-04 08:08:09 +0000