[BasicAA] Move assumption tracking into AAQI

D91936 placed the tracking for the assumptions into BasicAA.
However, when recursing over phis, we may use fresh AAQI instances.
In this case AssumptionBasedResults from an inner AAQI can reesult
in a removal of an element from the outer AAQI.

To avoid this, move the tracking into AAQI. This generally makes
more sense, as the NoAlias assumptions themselves are also stored
in AAQI.

The test case only produces an assertion failure with D90094
reapplied. I think the issue exists independently of that change
as well, but I wasn't able to come up with a reproducer.

diff --git a/llvm/include/llvm/Analysis/AliasAnalysis.h b/llvm/include/llvm/Analysis/AliasAnalysis.h
index 8a3ea62..9f74612 100644 (file)
--- a/llvm/include/llvm/Analysis/AliasAnalysis.h
+++ b/llvm/include/llvm/Analysis/AliasAnalysis.h
@@ -360,6 +360,14 @@ public:
   using IsCapturedCacheT = SmallDenseMap<const Value *, bool, 8>;
   IsCapturedCacheT IsCapturedCache;
 
+  /// How many active NoAlias assumption uses there are.
+  int NumAssumptionUses = 0;
+
+  /// Location pairs for which an assumption based result is currently stored.
+  /// Used to remove all potentially incorrect results from the cache if an
+  /// assumption is disproven.
+  SmallVector<AAQueryInfo::LocPair, 4> AssumptionBasedResults;
+
   AAQueryInfo() : AliasCache(), IsCapturedCache() {}
 };
 

diff --git a/llvm/include/llvm/Analysis/BasicAliasAnalysis.h b/llvm/include/llvm/Analysis/BasicAliasAnalysis.h
index 635c355..01b7345 100644 (file)
--- a/llvm/include/llvm/Analysis/BasicAliasAnalysis.h
+++ b/llvm/include/llvm/Analysis/BasicAliasAnalysis.h
@@ -190,14 +190,6 @@ private:
   /// Tracks instructions visited by pointsToConstantMemory.
   SmallPtrSet<const Value *, 16> Visited;
 
-  /// How many active NoAlias assumption uses there are.
-  int NumAssumptionUses = 0;
-
-  /// Location pairs for which an assumption based result is currently stored.
-  /// Used to remove all potentially incorrect results from the cache if an
-  /// assumption is disproven.
-  SmallVector<AAQueryInfo::LocPair, 4> AssumptionBasedResults;
-
   static const Value *
   GetLinearExpression(const Value *V, APInt &Scale, APInt &Offset,
                       unsigned &ZExtBits, unsigned &SExtBits,

diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index 313a85c..cfed32b 100644 (file)
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -1619,13 +1619,13 @@ AliasResult BasicAAResult::aliasCheck(const Value *V1, LocationSize V1Size,
     if (!Entry.isDefinitive()) {
       // Remember that we used an assumption.
       ++Entry.NumAssumptionUses;
-      ++NumAssumptionUses;
+      ++AAQI.NumAssumptionUses;
     }
     return Entry.Result;
   }
 
-  int OrigNumAssumptionUses = NumAssumptionUses;
-  unsigned OrigNumAssumptionBasedResults = AssumptionBasedResults.size();
+  int OrigNumAssumptionUses = AAQI.NumAssumptionUses;
+  unsigned OrigNumAssumptionBasedResults = AAQI.AssumptionBasedResults.size();
   AliasResult Result = aliasCheckRecursive(V1, V1Size, V1AAInfo, V2, V2Size,
                                            V2AAInfo, AAQI, O1, O2);
 
@@ -1639,7 +1639,7 @@ AliasResult BasicAAResult::aliasCheck(const Value *V1, LocationSize V1Size,
     Result = MayAlias;
 
   // This is a definitive result now, when considered as a root query.
-  NumAssumptionUses -= Entry.NumAssumptionUses;
+  AAQI.NumAssumptionUses -= Entry.NumAssumptionUses;
   Entry.Result = Result;
   Entry.NumAssumptionUses = -1;
 
@@ -1647,13 +1647,13 @@ AliasResult BasicAAResult::aliasCheck(const Value *V1, LocationSize V1Size,
   // been based on this assumption. Do this after the Entry updates above to
   // avoid iterator invalidation.
   if (AssumptionDisproven)
-    while (AssumptionBasedResults.size() > OrigNumAssumptionBasedResults)
-      AAQI.AliasCache.erase(AssumptionBasedResults.pop_back_val());
+    while (AAQI.AssumptionBasedResults.size() > OrigNumAssumptionBasedResults)
+      AAQI.AliasCache.erase(AAQI.AssumptionBasedResults.pop_back_val());
 
   // The result may still be based on assumptions higher up in the chain.
   // Remember it, so it can be purged from the cache later.
-  if (OrigNumAssumptionUses != NumAssumptionUses && Result != MayAlias)
-    AssumptionBasedResults.push_back(Locs);
+  if (OrigNumAssumptionUses != AAQI.NumAssumptionUses && Result != MayAlias)
+    AAQI.AssumptionBasedResults.push_back(Locs);
   return Result;
 }
 

diff --git a/llvm/test/Transforms/MemCpyOpt/aa-recursion-assertion-failure.ll b/llvm/test/Transforms/MemCpyOpt/aa-recursion-assertion-failure.ll
new file mode 100644 (file)
index 0000000..8952903
--- /dev/null
+++ b/llvm/test/Transforms/MemCpyOpt/aa-recursion-assertion-failure.ll
@@ -0,0 +1,86 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -scoped-noalias-aa -memcpyopt < %s | FileCheck %s
+
+; ModuleID = '<stdin>'
+source_filename = "test.cpp"
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64-unknown-linux-android21"
+
+define dso_local void @_Z1ml(i64 %e) {
+; CHECK-LABEL: @_Z1ml(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[L:%.*]] = alloca i8, align 1
+; CHECK-NEXT:    br label [[WHILE_COND:%.*]]
+; CHECK:       for.cond.while.cond.loopexit_crit_edge.us-lcssa:
+; CHECK-NEXT:    br label [[WHILE_COND_LOOPEXIT:%.*]]
+; CHECK:       while.cond.loopexit:
+; CHECK-NEXT:    [[TMP0:%.*]] = phi i8* [ [[ADD_PTR_I:%.*]], [[FOR_COND_WHILE_COND_LOOPEXIT_CRIT_EDGE_US_LCSSA:%.*]] ], [ [[TMP1:%.*]], [[WHILE_COND]] ]
+; CHECK-NEXT:    [[I_1_LCSSA:%.*]] = phi i8* [ [[I_2:%.*]], [[FOR_COND_WHILE_COND_LOOPEXIT_CRIT_EDGE_US_LCSSA]] ], [ [[I_0:%.*]], [[WHILE_COND]] ]
+; CHECK-NEXT:    br label [[WHILE_COND]]
+; CHECK:       while.cond:
+; CHECK-NEXT:    [[TMP1]] = phi i8* [ [[L]], [[ENTRY:%.*]] ], [ [[TMP0]], [[WHILE_COND_LOOPEXIT]] ]
+; CHECK-NEXT:    [[I_0]] = phi i8* [ [[L]], [[ENTRY]] ], [ [[I_1_LCSSA]], [[WHILE_COND_LOOPEXIT]] ]
+; CHECK-NEXT:    br i1 undef, label [[FOR_BODY_LR_PH:%.*]], label [[WHILE_COND_LOOPEXIT]]
+; CHECK:       for.body.lr.ph:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[TMP2:%.*]] = phi i8* [ [[TMP1]], [[FOR_BODY_LR_PH]] ], [ [[ADD_PTR_I]], [[IF_END5:%.*]] ]
+; CHECK-NEXT:    [[I_15:%.*]] = phi i8* [ [[I_0]], [[FOR_BODY_LR_PH]] ], [ [[I_2]], [[IF_END5]] ]
+; CHECK-NEXT:    [[ADD_PTR_I]] = getelementptr inbounds i8, i8* [[TMP2]], i64 [[E:%.*]]
+; CHECK-NEXT:    [[TMP3:%.*]] = load i8, i8* [[TMP2]], align 1, !noalias !0
+; CHECK-NEXT:    [[TMP4:%.*]] = load i8, i8* [[I_15]], align 1, !alias.scope !0
+; CHECK-NEXT:    store i8 [[TMP4]], i8* [[TMP2]], align 1
+; CHECK-NEXT:    br label [[_Z1DPCS_L_EXIT:%.*]]
+; CHECK:       _Z1dPcS_l.exit:
+; CHECK-NEXT:    br i1 undef, label [[IF_THEN3:%.*]], label [[IF_END5]]
+; CHECK:       if.then3:
+; CHECK-NEXT:    [[ADD_PTR4:%.*]] = getelementptr inbounds i8, i8* [[I_15]], i64 [[E]]
+; CHECK-NEXT:    br label [[IF_END5]]
+; CHECK:       if.end5:
+; CHECK-NEXT:    [[I_2]] = phi i8* [ [[ADD_PTR4]], [[IF_THEN3]] ], [ [[I_15]], [[_Z1DPCS_L_EXIT]] ]
+; CHECK-NEXT:    br i1 false, label [[FOR_BODY]], label [[FOR_COND_WHILE_COND_LOOPEXIT_CRIT_EDGE_US_LCSSA]]
+;
+entry:
+  %l = alloca i8, align 1
+  br label %while.cond
+
+for.cond.while.cond.loopexit_crit_edge.us-lcssa:  ; preds = %if.end5
+  br label %while.cond.loopexit
+
+while.cond.loopexit:                              ; preds = %while.cond, %for.cond.while.cond.loopexit_crit_edge.us-lcssa
+  %0 = phi i8* [ %add.ptr.i, %for.cond.while.cond.loopexit_crit_edge.us-lcssa ], [ %1, %while.cond ]
+  %i.1.lcssa = phi i8* [ %i.2, %for.cond.while.cond.loopexit_crit_edge.us-lcssa ], [ %i.0, %while.cond ]
+  br label %while.cond
+
+while.cond:                                       ; preds = %while.cond.loopexit, %entry
+  %1 = phi i8* [ %l, %entry ], [ %0, %while.cond.loopexit ]
+  %i.0 = phi i8* [ %l, %entry ], [ %i.1.lcssa, %while.cond.loopexit ]
+  br i1 undef, label %for.body.lr.ph, label %while.cond.loopexit
+
+for.body.lr.ph:                                   ; preds = %while.cond
+  br label %for.body
+
+for.body:                                         ; preds = %if.end5, %for.body.lr.ph
+  %2 = phi i8* [ %1, %for.body.lr.ph ], [ %add.ptr.i, %if.end5 ]
+  %i.15 = phi i8* [ %i.0, %for.body.lr.ph ], [ %i.2, %if.end5 ]
+  %add.ptr.i = getelementptr inbounds i8, i8* %2, i64 %e
+  %3 = load i8, i8* %2, align 1, !noalias !0
+  %4 = load i8, i8* %i.15, align 1, !alias.scope !0
+  store i8 %4, i8* %2, align 1
+  br label %_Z1dPcS_l.exit
+
+_Z1dPcS_l.exit:                                   ; preds = %for.body
+  br i1 undef, label %if.then3, label %if.end5
+
+if.then3:                                         ; preds = %_Z1dPcS_l.exit
+  %add.ptr4 = getelementptr inbounds i8, i8* %i.15, i64 %e
+  br label %if.end5
+
+if.end5:                                          ; preds = %if.then3, %_Z1dPcS_l.exit
+  %i.2 = phi i8* [ %add.ptr4, %if.then3 ], [ %i.15, %_Z1dPcS_l.exit ]
+  br i1 false, label %for.body, label %for.cond.while.cond.loopexit_crit_edge.us-lcssa
+}
+
+!0 = !{!1}
+!1 = distinct !{!1, !2, !"_Z1dPcS_l: %h"}
+!2 = distinct !{!2, !"_Z1dPcS_l"}