[flang] Handle empty array references in DATA statements

When an array reference in a DATA statement is empty due to an empty vector subscript or a section lower bound being higher than its upper bound with a positive stride (or lower with negative), ensure that isEmpty() is correct afterwards so that such an empty array reference doesn't terminate processing of that DATA statement block. Fixes #63512. Differential Revision: https://reviews.llvm.org/D153799
llvm · Jun 27, 2023 · 59f0959 · 59f0959
1 parent 5b55eb1
commit 59f0959
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Showing 2 changed files with 20 additions and 10 deletions.
diff --git a/flang/lib/Evaluate/fold-designator.cpp b/flang/lib/Evaluate/fold-designator.cpp
@@ -90,6 +90,8 @@ std::optional<OffsetSymbol> DesignatorFolder::FoldDesignator(
                               result->Augment((at - lower) * stride);
                               which = quotient;
                               return true;
+                            } else {
+                              isEmpty_ = true;
                             }
                           }
                           return false;
@@ -100,16 +102,20 @@ std::optional<OffsetSymbol> DesignatorFolder::FoldDesignator(
                           auto end{ToInt64(Fold(context_,
                               triplet.upper().value_or(ExtentExpr{upper})))};
                           auto step{ToInt64(Fold(context_, triplet.stride()))};
-                          if (start && end && step && *step != 0) {
-                            ConstantSubscript range{
-                                (*end - *start + *step) / *step};
-                            if (range > 0) {
-                              auto quotient{which / range};
-                              auto remainder{which - range * quotient};
-                              auto j{*start + remainder * *step};
-                              result->Augment((j - lower) * stride);
-                              which = quotient;
-                              return true;
+                          if (start && end && step) {
+                            if (*step != 0) {
+                              ConstantSubscript range{
+                                  (*end - *start + *step) / *step};
+                              if (range > 0) {
+                                auto quotient{which / range};
+                                auto remainder{which - range * quotient};
+                                auto j{*start + remainder * *step};
+                                result->Augment((j - lower) * stride);
+                                which = quotient;
+                                return true;
+                              } else {
+                                isEmpty_ = true;
+                              }
                             }
                           }
                           return false;

diff --git a/flang/test/Semantics/data05.f90 b/flang/test/Semantics/data05.f90
@@ -89,4 +89,8 @@ subroutine s12
     procedure(rfunc), pointer :: pp ! CHECK: pp, EXTERNAL, POINTER (Function, InDataStmt) size=8 offset=0: ProcEntity rfunc => rfunc2
     data pp/rfunc2/
   end subroutine
+  subroutine s13
+    integer j(2)
+    data j(2:1), j(1:2) /1,2/ ! CHECK: j (InDataStmt) size=8 offset=0: ObjectEntity type: INTEGER(4) shape: 1_8:2_8 init:[INTEGER(4)::1_4,2_4]
+  end subroutine
 end module