[flang][debug] Add stride information for assumed shape array.

[abidh]

Without this information, debugger could present wrong values for arrays in certain cases as shown in issue #105646.

Fixes #105646.

[llvmbot]

@llvm/pr-subscribers-flang-fir-hlfir

Author: Abid Qadeer (abidh)

Changes

Without this information, debugger could present wrong values for arrays in certain cases as shown in issue #105646.

Fixes #105646.

---

Full diff: https://github.com/llvm/llvm-project/pull/106703.diff

3 Files Affected:

• (modified) flang/lib/Optimizer/Transforms/DebugTypeGenerator.cpp (+10-2)
• (modified) flang/test/Integration/debug-assumed-shape-array.f90 (+2-2)
• (modified) flang/test/Transforms/debug-assumed-shape-array.fir (+2-2)

diff --git a/flang/lib/Optimizer/Transforms/DebugTypeGenerator.cpp b/flang/lib/Optimizer/Transforms/DebugTypeGenerator.cpp
index 54f2a12d800085..a3f44f12d828e3 100644
--- a/flang/lib/Optimizer/Transforms/DebugTypeGenerator.cpp
+++ b/flang/lib/Optimizer/Transforms/DebugTypeGenerator.cpp
@@ -139,10 +139,18 @@ mlir::LLVM::DITypeAttr DebugTypeGenerator::convertBoxedSequenceType(
         mlir::LLVM::DIExpressionAttr::get(context, ops);
     ops.clear();
 
+    addOp(llvm::dwarf::DW_OP_push_object_address, {});
+    addOp(llvm::dwarf::DW_OP_plus_uconst,
+          {offset + (indexSize * kDimStridePos)});
+    addOp(llvm::dwarf::DW_OP_deref, {});
+    // stride[i] = *(base_addr + offset + (indexSize * kDimStridePos))
+    mlir::LLVM::DIExpressionAttr strideAttr =
+        mlir::LLVM::DIExpressionAttr::get(context, ops);
+    ops.clear();
+
     offset += dimsSize;
     mlir::LLVM::DISubrangeAttr subrangeTy = mlir::LLVM::DISubrangeAttr::get(
-        context, countAttr, lowerAttr, /*upperBound=*/nullptr,
-        /*stride=*/nullptr);
+        context, countAttr, lowerAttr, /*upperBound=*/nullptr, strideAttr);
     elements.push_back(subrangeTy);
   }
   return mlir::LLVM::DICompositeTypeAttr::get(
diff --git a/flang/test/Integration/debug-assumed-shape-array.f90 b/flang/test/Integration/debug-assumed-shape-array.f90
index a23ffa13cf0ac6..9a439e20d19816 100644
--- a/flang/test/Integration/debug-assumed-shape-array.f90
+++ b/flang/test/Integration/debug-assumed-shape-array.f90
@@ -8,6 +8,6 @@ end subroutine ff
 
 ! CHECK-DAG: !DICompositeType(tag: DW_TAG_array_type{{.*}}elements: ![[ELEMS:[0-9]+]], dataLocation: !DIExpression(DW_OP_push_object_address, DW_OP_deref))
 ! CHECK-DAG: ![[ELEMS]] = !{![[ELEM1:[0-9]+]], ![[ELEM2:[0-9]+]]}
-! CHECK-DAG: ![[ELEM1]] = !DISubrange(count: !DIExpression(DW_OP_push_object_address, DW_OP_plus_uconst, 32, DW_OP_deref), lowerBound: !DIExpression(DW_OP_push_object_address, DW_OP_plus_uconst, 24, DW_OP_deref))
-! CHECK-DAG: ![[ELEM2]] = !DISubrange(count: !DIExpression(DW_OP_push_object_address, DW_OP_plus_uconst, 56, DW_OP_deref), lowerBound: !DIExpression(DW_OP_push_object_address, DW_OP_plus_uconst, 48, DW_OP_deref))
+! CHECK-DAG: ![[ELEM1]] = !DISubrange(count: !DIExpression(DW_OP_push_object_address, DW_OP_plus_uconst, 32, DW_OP_deref), lowerBound: !DIExpression(DW_OP_push_object_address, DW_OP_plus_uconst, 24, DW_OP_deref), stride: !DIExpression(DW_OP_push_object_address, DW_OP_plus_uconst, 40, DW_OP_deref))
+! CHECK-DAG: ![[ELEM2]] = !DISubrange(count: !DIExpression(DW_OP_push_object_address, DW_OP_plus_uconst, 56, DW_OP_deref), lowerBound: !DIExpression(DW_OP_push_object_address, DW_OP_plus_uconst, 48, DW_OP_deref), stride: !DIExpression(DW_OP_push_object_address, DW_OP_plus_uconst, 64, DW_OP_deref))
 
diff --git a/flang/test/Transforms/debug-assumed-shape-array.fir b/flang/test/Transforms/debug-assumed-shape-array.fir
index 0a9b84ad253aab..d1e64297acea7d 100644
--- a/flang/test/Transforms/debug-assumed-shape-array.fir
+++ b/flang/test/Transforms/debug-assumed-shape-array.fir
@@ -11,6 +11,6 @@ module attributes {dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry<i64, dense<64> :
 #loc2 = loc("test1.f90":3:16)
 
 // CHECK: #llvm.di_composite_type<tag = DW_TAG_array_type
-// CHECK-SAME: elements = #llvm.di_subrange<count = #llvm.di_expression<[DW_OP_push_object_address, DW_OP_plus_uconst(32), DW_OP_deref]>, lowerBound = #llvm.di_expression<[DW_OP_push_object_address, DW_OP_plus_uconst(24), DW_OP_deref]>>,
-// CHECK-SAME: #llvm.di_subrange<count = #llvm.di_expression<[DW_OP_push_object_address, DW_OP_plus_uconst(56), DW_OP_deref]>, lowerBound = #llvm.di_expression<[DW_OP_push_object_address, DW_OP_plus_uconst(48), DW_OP_deref]>>
+// CHECK-SAME: elements = #llvm.di_subrange<count = #llvm.di_expression<[DW_OP_push_object_address, DW_OP_plus_uconst(32), DW_OP_deref]>, lowerBound = #llvm.di_expression<[DW_OP_push_object_address, DW_OP_plus_uconst(24), DW_OP_deref]>, stride = #llvm.di_expression<[DW_OP_push_object_address, DW_OP_plus_uconst(40), DW_OP_deref]>>,
+// CHECK-SAME: #llvm.di_subrange<count = #llvm.di_expression<[DW_OP_push_object_address, DW_OP_plus_uconst(56), DW_OP_deref]>, lowerBound = #llvm.di_expression<[DW_OP_push_object_address, DW_OP_plus_uconst(48), DW_OP_deref]>, stride = #llvm.di_expression<[DW_OP_push_object_address, DW_OP_plus_uconst(64), DW_OP_deref]>>
 // CHECK-SAME: dataLocation = <[DW_OP_push_object_address, DW_OP_deref]>>

[jinisusan]

LGTM except for a nit: The comment at line 19 should instead be changed to: "For each dimension, find the offsets of count, lower bound and stride in the ..."