[llvm] r297539 - Use a WeakVH for UnknownInstructions in AliasSetTracker
Sanjoy Das via llvm-commits
llvm-commits at lists.llvm.org
Fri Mar 10 17:15:49 PST 2017
Author: sanjoy
Date: Fri Mar 10 19:15:48 2017
New Revision: 297539
URL: http://llvm.org/viewvc/llvm-project?rev=297539&view=rev
Log:
Use a WeakVH for UnknownInstructions in AliasSetTracker
Summary:
This change solves the same problem as D30726, except that this only
throws out the bathwater.
AST was not correctly tracking and deleting UnknownInstructions via
handles. The existing code only tracks "pointers" in its
`ASTCallbackVH`, so an UnknownInstruction (that isn't also def'ing a
pointer used by another memory instruction) never gets a
`ASTCallbackVH`.
There are two other ways to solve this problem:
- Use the `PointerRec` scheme for both known and unknown instructions.
- Use a `CallbackVH` that erases the offending Instruction from the
UnknownInstruction list.
Both of the above changes seemed to be significantly (and unnecessarily
IMO) more complex than this.
Reviewers: chandlerc, dberlin, hfinkel, reames
Subscribers: mcrosier, llvm-commits
Differential Revision: https://reviews.llvm.org/D30849
Added:
llvm/trunk/test/Transforms/LICM/pr32129.ll
Modified:
llvm/trunk/include/llvm/Analysis/AliasSetTracker.h
llvm/trunk/lib/Analysis/AliasSetTracker.cpp
Modified: llvm/trunk/include/llvm/Analysis/AliasSetTracker.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/AliasSetTracker.h?rev=297539&r1=297538&r2=297539&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/AliasSetTracker.h (original)
+++ llvm/trunk/include/llvm/Analysis/AliasSetTracker.h Fri Mar 10 19:15:48 2017
@@ -121,7 +121,10 @@ class AliasSet : public ilist_node<Alias
AliasSet *Forward;
/// All instructions without a specific address in this alias set.
- std::vector<AssertingVH<Instruction> > UnknownInsts;
+ /// In rare cases this vector can have a null'ed out WeakVH
+ /// instances (can happen if some other loop pass deletes an
+ /// instruction in this list).
+ std::vector<WeakVH> UnknownInsts;
/// Number of nodes pointing to this AliasSet plus the number of AliasSets
/// forwarding to it.
@@ -171,7 +174,7 @@ class AliasSet : public ilist_node<Alias
Instruction *getUnknownInst(unsigned i) const {
assert(i < UnknownInsts.size());
- return UnknownInsts[i];
+ return cast_or_null<Instruction>(UnknownInsts[i]);
}
public:
Modified: llvm/trunk/lib/Analysis/AliasSetTracker.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/AliasSetTracker.cpp?rev=297539&r1=297538&r2=297539&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/AliasSetTracker.cpp (original)
+++ llvm/trunk/lib/Analysis/AliasSetTracker.cpp Fri Mar 10 19:15:48 2017
@@ -199,9 +199,10 @@ bool AliasSet::aliasesPointer(const Valu
// Check the unknown instructions...
if (!UnknownInsts.empty()) {
for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i)
- if (AA.getModRefInfo(UnknownInsts[i],
- MemoryLocation(Ptr, Size, AAInfo)) != MRI_NoModRef)
- return true;
+ if (auto *Inst = getUnknownInst(i))
+ if (AA.getModRefInfo(Inst, MemoryLocation(Ptr, Size, AAInfo)) !=
+ MRI_NoModRef)
+ return true;
}
return false;
@@ -217,10 +218,12 @@ bool AliasSet::aliasesUnknownInst(const
return false;
for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
- ImmutableCallSite C1(getUnknownInst(i)), C2(Inst);
- if (!C1 || !C2 || AA.getModRefInfo(C1, C2) != MRI_NoModRef ||
- AA.getModRefInfo(C2, C1) != MRI_NoModRef)
- return true;
+ if (auto *Inst = getUnknownInst(i)) {
+ ImmutableCallSite C1(Inst), C2(Inst);
+ if (!C1 || !C2 || AA.getModRefInfo(C1, C2) != MRI_NoModRef ||
+ AA.getModRefInfo(C2, C1) != MRI_NoModRef)
+ return true;
+ }
}
for (iterator I = begin(), E = end(); I != E; ++I)
@@ -471,7 +474,8 @@ void AliasSetTracker::add(const AliasSet
// If there are any call sites in the alias set, add them to this AST.
for (unsigned i = 0, e = AS.UnknownInsts.size(); i != e; ++i)
- add(AS.UnknownInsts[i]);
+ if (auto *Inst = AS.getUnknownInst(i))
+ add(Inst);
// Loop over all of the pointers in this alias set.
for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
@@ -489,19 +493,6 @@ void AliasSetTracker::add(const AliasSet
// dangling pointers to deleted instructions.
//
void AliasSetTracker::deleteValue(Value *PtrVal) {
- // If this is a call instruction, remove the callsite from the appropriate
- // AliasSet (if present).
- if (Instruction *Inst = dyn_cast<Instruction>(PtrVal)) {
- if (Inst->mayReadOrWriteMemory()) {
- // Scan all the alias sets to see if this call site is contained.
- for (iterator I = begin(), E = end(); I != E;) {
- iterator Cur = I++;
- if (!Cur->Forward)
- Cur->removeUnknownInst(*this, Inst);
- }
- }
- }
-
// First, look up the PointerRec for this pointer.
PointerMapType::iterator I = PointerMap.find_as(PtrVal);
if (I == PointerMap.end()) return; // Noop
@@ -633,7 +624,8 @@ void AliasSet::print(raw_ostream &OS) co
OS << "\n " << UnknownInsts.size() << " Unknown instructions: ";
for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
if (i) OS << ", ";
- UnknownInsts[i]->printAsOperand(OS);
+ if (auto *I = getUnknownInst(i))
+ I->printAsOperand(OS);
}
}
OS << "\n";
Added: llvm/trunk/test/Transforms/LICM/pr32129.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LICM/pr32129.ll?rev=297539&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LICM/pr32129.ll (added)
+++ llvm/trunk/test/Transforms/LICM/pr32129.ll Fri Mar 10 19:15:48 2017
@@ -0,0 +1,18 @@
+; RUN: opt -S -licm -loop-unswitch -licm < %s | FileCheck %s
+
+declare void @llvm.experimental.guard(i1, ...)
+
+define void @test() {
+; CHECK-LABEL: @test(
+; CHECK-NOT: guard
+entry:
+ br label %header
+
+header:
+ br label %loop
+
+loop:
+ %0 = icmp ult i32 0, 400
+ call void (i1, ...) @llvm.experimental.guard(i1 %0, i32 9) [ "deopt"() ]
+ br i1 undef, label %header, label %loop
+}
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