[flang-commits] [flang] aca9016 - [flang] Fix crash on SELECT RANK

[Peter Klausler via flang-commits]

Author: Peter Klausler
Date: 2023-02-12T12:16:28-08:00
New Revision: aca9016bcde040ea03512ee1e23f61f08b3b07b9

URL: https://github.com/llvm/llvm-project/commit/aca9016bcde040ea03512ee1e23f61f08b3b07b9
DIFF: https://github.com/llvm/llvm-project/commit/aca9016bcde040ea03512ee1e23f61f08b3b07b9.diff

LOG: [flang] Fix crash on SELECT RANK

In some circumstances, such as in compile-time array shape analysis,
clients of the utility function ResolveAssociations() don't really
want it to drill all of the way down to an assumed-rank dummy argument.
Add a variation, ResolveAssociationsExceptSelectRank(), that
will return a specific rank case's AssocEntity symbol instead.
This fixes a crash in subscript validation checking that stemmed from
deducing an incorrect number of lower and upper bound expressions
from a specific rank case association entity.

Differential Revision: https://reviews.llvm.org/D143778

Added: 
    

Modified: 
    flang/include/flang/Evaluate/tools.h
    flang/lib/Evaluate/shape.cpp
    flang/lib/Evaluate/tools.cpp
    flang/lib/Semantics/expression.cpp

Removed: 
    


################################################################################
diff  --git a/flang/include/flang/Evaluate/tools.h b/flang/include/flang/Evaluate/tools.h
index 291557153453b..448909d365940 100644
--- a/flang/include/flang/Evaluate/tools.h
+++ b/flang/include/flang/Evaluate/tools.h
@@ -1218,8 +1218,10 @@ bool IsEventTypeOrLockType(const DerivedTypeSpec *);
 // of the construct entity.
 // (E.g., for ASSOCIATE(x => y%z), ResolveAssociations(x) returns x,
 // while GetAssociationRoot(x) returns y.)
+// ResolveAssociationsExceptSelectRank() stops at a RANK case symbol.
 const Symbol &ResolveAssociations(const Symbol &);
 const Symbol &GetAssociationRoot(const Symbol &);
+const Symbol &ResolveAssociationsExceptSelectRank(const Symbol &);
 
 const Symbol *FindCommonBlockContaining(const Symbol &);
 int CountLenParameters(const DerivedTypeSpec &);

diff  --git a/flang/lib/Evaluate/shape.cpp b/flang/lib/Evaluate/shape.cpp
index 661116bd4b210..6f6baaec2b61e 100644
--- a/flang/lib/Evaluate/shape.cpp
+++ b/flang/lib/Evaluate/shape.cpp
@@ -462,7 +462,7 @@ MaybeExtentExpr GetAssociatedExtent(const NamedEntity &base,
 MaybeExtentExpr GetExtent(const NamedEntity &base, int dimension) {
   CHECK(dimension >= 0);
   const Symbol &last{base.GetLastSymbol()};
-  const Symbol &symbol{ResolveAssociations(last)};
+  const Symbol &symbol{ResolveAssociationsExceptSelectRank(last)};
   if (const auto *assoc{last.detailsIf<semantics::AssocEntityDetails>()}) {
     if (assoc->rank()) { // SELECT RANK case
       if (semantics::IsDescriptor(symbol) && dimension < *assoc->rank()) {
@@ -559,7 +559,8 @@ MaybeExtentExpr ComputeUpperBound(
 }
 
 MaybeExtentExpr GetRawUpperBound(const NamedEntity &base, int dimension) {
-  const Symbol &symbol{ResolveAssociations(base.GetLastSymbol())};
+  const Symbol &symbol{
+      ResolveAssociationsExceptSelectRank(base.GetLastSymbol())};
   if (const auto *details{symbol.detailsIf<semantics::ObjectEntityDetails>()}) {
     int rank{details->shape().Rank()};
     if (dimension < rank) {
@@ -608,7 +609,8 @@ static MaybeExtentExpr GetExplicitUBOUND(
 
 static MaybeExtentExpr GetUBOUND(
     FoldingContext *context, const NamedEntity &base, int dimension) {
-  const Symbol &symbol{ResolveAssociations(base.GetLastSymbol())};
+  const Symbol &symbol{
+      ResolveAssociationsExceptSelectRank(base.GetLastSymbol())};
   if (const auto *details{symbol.detailsIf<semantics::ObjectEntityDetails>()}) {
     int rank{details->shape().Rank()};
     if (dimension < rank) {
@@ -642,7 +644,8 @@ MaybeExtentExpr GetUBOUND(
 }
 
 static Shape GetUBOUNDs(FoldingContext *context, const NamedEntity &base) {
-  const Symbol &symbol{ResolveAssociations(base.GetLastSymbol())};
+  const Symbol &symbol{
+      ResolveAssociationsExceptSelectRank(base.GetLastSymbol())};
   if (const auto *details{symbol.detailsIf<semantics::ObjectEntityDetails>()}) {
     Shape result;
     int dim{0};

diff  --git a/flang/lib/Evaluate/tools.cpp b/flang/lib/Evaluate/tools.cpp
index 840932c0e0dd6..bf530f857b652 100644
--- a/flang/lib/Evaluate/tools.cpp
+++ b/flang/lib/Evaluate/tools.cpp
@@ -1212,6 +1212,18 @@ const Symbol &ResolveAssociations(const Symbol &original) {
   return symbol;
 }
 
+const Symbol &ResolveAssociationsExceptSelectRank(const Symbol &original) {
+  const Symbol &symbol{original.GetUltimate()};
+  if (const auto *details{symbol.detailsIf<AssocEntityDetails>()}) {
+    if (!details->rank()) {
+      if (const Symbol * nested{UnwrapWholeSymbolDataRef(details->expr())}) {
+        return ResolveAssociations(*nested);
+      }
+    }
+  }
+  return symbol;
+}
+
 // When a construct association maps to a variable, and that variable
 // is not an array with a vector-valued subscript, return the base
 // Symbol of that variable, else nullptr.  Descends into other construct

diff  --git a/flang/lib/Semantics/expression.cpp b/flang/lib/Semantics/expression.cpp
index b61b97a80554b..116aa7f1504e5 100644
--- a/flang/lib/Semantics/expression.cpp
+++ b/flang/lib/Semantics/expression.cpp
@@ -312,7 +312,9 @@ MaybeExpr ExpressionAnalyzer::ApplySubscripts(
 void ExpressionAnalyzer::CheckConstantSubscripts(ArrayRef &ref) {
   // Fold subscript expressions and check for an empty triplet.
   Shape lb{GetLBOUNDs(foldingContext_, ref.base())};
+  CHECK(lb.size() >= ref.subscript().size());
   Shape ub{GetUBOUNDs(foldingContext_, ref.base())};
+  CHECK(ub.size() >= ref.subscript().size());
   bool anyPossiblyEmptyDim{false};
   int dim{0};
   for (Subscript &ss : ref.subscript()) {