[llvm] [AliasSetTracker] Use ModRefInfo (NFC) (PR #217917)
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Fri Aug 21 11:18:56 PDT 2026
llvmorg-github-actions[bot] wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-analysis
Author: Nikita Popov (nikic)
<details>
<summary>Changes</summary>
Use ModRefInfo instead of an equivalent custom AccessLattice.
I did not bit-pack the value (which would have required adding casts to/from ModRefInfo everywhere) because this doesn't impact the size of the structure on 64-bit hosts anyway.
---
Full diff: https://github.com/llvm/llvm-project/pull/217917.diff
2 Files Affected:
- (modified) llvm/include/llvm/Analysis/AliasSetTracker.h (+10-20)
- (modified) llvm/lib/Analysis/AliasSetTracker.cpp (+26-30)
``````````diff
diff --git a/llvm/include/llvm/Analysis/AliasSetTracker.h b/llvm/include/llvm/Analysis/AliasSetTracker.h
index 2f3418217e1b4..cd76ab6bdad79 100644
--- a/llvm/include/llvm/Analysis/AliasSetTracker.h
+++ b/llvm/include/llvm/Analysis/AliasSetTracker.h
@@ -26,6 +26,7 @@
#include "llvm/IR/PassManager.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Support/Compiler.h"
+#include "llvm/Support/ModRef.h"
#include <cassert>
#include <vector>
@@ -41,7 +42,6 @@ class Function;
class Instruction;
class StoreInst;
class LoadInst;
-enum class ModRefInfo : uint8_t;
class raw_ostream;
class VAArgInst;
class Value;
@@ -60,26 +60,12 @@ class AliasSet : public ilist_node<AliasSet> {
/// Number of nodes pointing to this AliasSet plus the number of AliasSets
/// forwarding to it.
- unsigned RefCount : 27;
+ unsigned RefCount : 30;
// Signifies that this set should be considered to alias any pointer.
// Use when the tracker holding this set is saturated.
unsigned AliasAny : 1;
- /// The kinds of access this alias set models.
- ///
- /// We keep track of whether this alias set merely refers to the locations of
- /// memory (and not any particular access), whether it modifies or references
- /// the memory, or whether it does both. The lattice goes from "NoAccess" to
- /// either RefAccess or ModAccess, then to ModRefAccess as necessary.
- enum AccessLattice {
- NoAccess = 0,
- RefAccess = 1,
- ModAccess = 2,
- ModRefAccess = RefAccess | ModAccess
- };
- unsigned Access : 2;
-
/// The kind of alias relationship between pointers of the set.
///
/// These represent conservatively correct alias results between any members
@@ -91,6 +77,9 @@ class AliasSet : public ilist_node<AliasSet> {
};
unsigned Alias : 1;
+ // The kinds of access this alias set models.
+ ModRefInfo Access;
+
void addRef() { ++RefCount; }
void dropRef(AliasSetTracker &AST) {
@@ -104,8 +93,8 @@ class AliasSet : public ilist_node<AliasSet> {
AliasSet &operator=(const AliasSet &) = delete;
/// Accessors...
- bool isRef() const { return Access & RefAccess; }
- bool isMod() const { return Access & ModAccess; }
+ bool isRef() const { return isRefSet(Access); }
+ bool isMod() const { return isModSet(Access); }
bool isMustAlias() const { return Alias == SetMustAlias; }
bool isMayAlias() const { return Alias == SetMayAlias; }
@@ -137,7 +126,8 @@ class AliasSet : public ilist_node<AliasSet> {
private:
// Can only be created by AliasSetTracker.
AliasSet()
- : RefCount(0), AliasAny(false), Access(NoAccess), Alias(SetMustAlias) {}
+ : RefCount(0), AliasAny(false), Alias(SetMustAlias),
+ Access(ModRefInfo::NoModRef) {}
LLVM_ABI void removeFromTracker(AliasSetTracker &AST);
@@ -253,7 +243,7 @@ class AliasSetTracker {
}
}
- AliasSet &addMemoryLocation(MemoryLocation Loc, AliasSet::AccessLattice E);
+ AliasSet &addMemoryLocation(MemoryLocation Loc, ModRefInfo MR);
AliasSet *mergeAliasSetsForMemoryLocation(const MemoryLocation &MemLoc,
AliasSet *PtrAS,
bool &MustAliasAll);
diff --git a/llvm/lib/Analysis/AliasSetTracker.cpp b/llvm/lib/Analysis/AliasSetTracker.cpp
index 1e2f05b60a9a3..7b5f58b827fe1 100644
--- a/llvm/lib/Analysis/AliasSetTracker.cpp
+++ b/llvm/lib/Analysis/AliasSetTracker.cpp
@@ -137,13 +137,13 @@ void AliasSet::addUnknownInst(Instruction *I, BatchAAResults &AA) {
!(I->use_empty() && match(I, m_Intrinsic<Intrinsic::invariant_start>()));
if (!MayWriteMemory) {
Alias = SetMayAlias;
- Access |= RefAccess;
+ Access |= ModRefInfo::Ref;
return;
}
// FIXME: This should use mod/ref information to make this not suck so bad
Alias = SetMayAlias;
- Access = ModRefAccess;
+ Access = ModRefInfo::ModRef;
}
/// aliasesMemoryLocation - If the specified memory location "may" (or must)
@@ -314,32 +314,32 @@ AliasSet &AliasSetTracker::getAliasSetFor(const MemoryLocation &MemLoc) {
}
void AliasSetTracker::add(const MemoryLocation &Loc) {
- addMemoryLocation(Loc, AliasSet::NoAccess);
+ addMemoryLocation(Loc, ModRefInfo::NoModRef);
}
void AliasSetTracker::add(LoadInst *LI) {
if (isStrongerThanMonotonic(LI->getOrdering()))
return addUnknown(LI);
- addMemoryLocation(MemoryLocation::get(LI), AliasSet::RefAccess);
+ addMemoryLocation(MemoryLocation::get(LI), ModRefInfo::Ref);
}
void AliasSetTracker::add(StoreInst *SI) {
if (isStrongerThanMonotonic(SI->getOrdering()))
return addUnknown(SI);
- addMemoryLocation(MemoryLocation::get(SI), AliasSet::ModAccess);
+ addMemoryLocation(MemoryLocation::get(SI), ModRefInfo::Mod);
}
void AliasSetTracker::add(VAArgInst *VAAI) {
- addMemoryLocation(MemoryLocation::get(VAAI), AliasSet::ModRefAccess);
+ addMemoryLocation(MemoryLocation::get(VAAI), ModRefInfo::ModRef);
}
void AliasSetTracker::add(AnyMemSetInst *MSI) {
- addMemoryLocation(MemoryLocation::getForDest(MSI), AliasSet::ModAccess);
+ addMemoryLocation(MemoryLocation::getForDest(MSI), ModRefInfo::Mod);
}
void AliasSetTracker::add(AnyMemTransferInst *MTI) {
- addMemoryLocation(MemoryLocation::getForDest(MTI), AliasSet::ModAccess);
- addMemoryLocation(MemoryLocation::getForSource(MTI), AliasSet::RefAccess);
+ addMemoryLocation(MemoryLocation::getForDest(MTI), ModRefInfo::Mod);
+ addMemoryLocation(MemoryLocation::getForSource(MTI), ModRefInfo::Ref);
}
void AliasSetTracker::addUnknown(Instruction *Inst) {
@@ -386,17 +386,6 @@ void AliasSetTracker::add(Instruction *I) {
// Handle all calls with known mod/ref sets genericall
if (auto *Call = dyn_cast<CallBase>(I))
if (Call->onlyAccessesArgMemory()) {
- auto getAccessFromModRef = [](ModRefInfo MRI) {
- if (isRefSet(MRI) && isModSet(MRI))
- return AliasSet::ModRefAccess;
- else if (isModSet(MRI))
- return AliasSet::ModAccess;
- else if (isRefSet(MRI))
- return AliasSet::RefAccess;
- else
- return AliasSet::NoAccess;
- };
-
ModRefInfo CallMask = AA.getMemoryEffects(Call).getModRef();
// Some intrinsics are marked as modifying memory for control flow
@@ -417,7 +406,7 @@ void AliasSetTracker::add(Instruction *I) {
ModRefInfo ArgMask = AA.getArgModRefInfo(Call, ArgIdx);
ArgMask &= CallMask;
if (!isNoModRef(ArgMask))
- addMemoryLocation(ArgLoc, getAccessFromModRef(ArgMask));
+ addMemoryLocation(ArgLoc, ArgMask);
}
return;
}
@@ -447,7 +436,7 @@ void AliasSetTracker::add(const AliasSetTracker &AST) {
// Loop over all of the memory locations in this alias set.
for (const MemoryLocation &ASMemLoc : AS.MemoryLocs)
- addMemoryLocation(ASMemLoc, (AliasSet::AccessLattice)AS.Access);
+ addMemoryLocation(ASMemLoc, AS.Access);
}
}
@@ -468,7 +457,7 @@ AliasSet &AliasSetTracker::mergeAllAliasSets() {
AliasSets.push_back(new AliasSet());
AliasAnyAS = &AliasSets.back();
AliasAnyAS->Alias = AliasSet::SetMayAlias;
- AliasAnyAS->Access = AliasSet::ModRefAccess;
+ AliasAnyAS->Access = ModRefInfo::ModRef;
AliasAnyAS->AliasAny = true;
for (auto *Cur : ASVector) {
@@ -489,9 +478,9 @@ AliasSet &AliasSetTracker::mergeAllAliasSets() {
}
AliasSet &AliasSetTracker::addMemoryLocation(MemoryLocation Loc,
- AliasSet::AccessLattice E) {
+ ModRefInfo MR) {
AliasSet &AS = getAliasSetFor(Loc);
- AS.Access |= E;
+ AS.Access |= MR;
if (!AliasAnyAS && (TotalAliasSetSize > SaturationThreshold)) {
// The AST is now saturated. From here on, we conservatively consider all
@@ -510,11 +499,18 @@ void AliasSet::print(raw_ostream &OS) const {
OS << " AliasSet[" << (const void*)this << ", " << RefCount << "] ";
OS << (Alias == SetMustAlias ? "must" : "may") << " alias, ";
switch (Access) {
- case NoAccess: OS << "No access "; break;
- case RefAccess: OS << "Ref "; break;
- case ModAccess: OS << "Mod "; break;
- case ModRefAccess: OS << "Mod/Ref "; break;
- default: llvm_unreachable("Bad value for Access!");
+ case ModRefInfo::NoModRef:
+ OS << "No access ";
+ break;
+ case ModRefInfo::Ref:
+ OS << "Ref ";
+ break;
+ case ModRefInfo::Mod:
+ OS << "Mod ";
+ break;
+ case ModRefInfo::ModRef:
+ OS << "Mod/Ref ";
+ break;
}
if (Forward)
OS << " forwarding to " << (void*)Forward;
``````````
</details>
https://github.com/llvm/llvm-project/pull/217917
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