Fix DIStringType length emitting in DWARF (2nd try)

MiloszSkobejko · igcbot · commit 6c4a933f631d · 2025-11-13T17:21:44.000+01:00
For some cases, there wasn't DW_AT_string_length added to
variable, which resulted in treating vla array as character.
diff --git a/IGC/DebugInfo/DwarfCompileUnit.cpp b/IGC/DebugInfo/DwarfCompileUnit.cpp
@@ -2044,8 +2044,22 @@ IGC::DIE *CompileUnit::constructVariableDIE(DbgVariable &DV, bool isScopeAbstrac
   LLVM_DEBUG(dbgs() << "[DwarfDebug] constructing DIE for variable <" << Name << ">\n");
   // Define variable debug information entry.
   DIE *VariableDie = new DIE(DV.getTag());
+
+  // If variable is abstract or scope is abstract attributes should be
+  // applied immediately
   DbgVariable *AbsVar = DV.getAbstractVariable();
   DIE *AbsDIE = AbsVar ? AbsVar->getDIE() : NULL;
+  if (isScopeAbstract || AbsDIE) {
+    applyVariableAttributes(DV, VariableDie, isScopeAbstract, AbsDIE);
+  } else {
+    insertDIE(const_cast<DILocalVariable *>(DV.getVariable()), VariableDie);
+  }
+  return VariableDie;
+}
+
+void CompileUnit::applyVariableAttributes(DbgVariable &DV, DIE *VariableDie, bool isScopeAbstract, DIE *AbsDIE) {
+  StringRef Name = DV.getName();
+  LLVM_DEBUG(dbgs() << "[DwarfDebug] applying attributes for DIE variable <" << Name << ">\n");
   if (AbsDIE) {
     addDIEEntry(VariableDie, dwarf::DW_AT_abstract_origin, AbsDIE);
   } else {
@@ -2063,7 +2077,7 @@ IGC::DIE *CompileUnit::constructVariableDIE(DbgVariable &DV, bool isScopeAbstrac
   if (isScopeAbstract) {
     DV.setDIE(VariableDie);
     LLVM_DEBUG(dbgs() << "  done. Variable is scope-abstract\n");
-    return VariableDie;
+    return;
   }
 
   // Add variable address.
@@ -2084,21 +2098,20 @@ IGC::DIE *CompileUnit::constructVariableDIE(DbgVariable &DV, bool isScopeAbstrac
 
     DV.setDIE(VariableDie);
     LLVM_DEBUG(dbgs() << "  done. Location is taken from .debug_loc\n");
-    return VariableDie;
+    return;
   }
 
   // Check if variable is described by a DBG_VALUE instruction.
   const Instruction *pDbgInst = DV.getDbgInst();
   if (!pDbgInst || !DV.currentLocationIsInlined()) {
     DV.setDIE(VariableDie);
     LLVM_DEBUG(dbgs() << " done. No dbg.inst assotiated\n");
-    return VariableDie;
+    return;
   }
 
   buildLocation(pDbgInst, DV, VariableDie);
 
   LLVM_DEBUG(dbgs() << " done. Location is emitted directly in DIE\n");
-  return VariableDie;
 }
 
 void CompileUnit::buildLocation(const llvm::Instruction *pDbgInst, DbgVariable &DV, IGC::DIE *VariableDie) {
diff --git a/IGC/DebugInfo/DwarfCompileUnit.hpp b/IGC/DebugInfo/DwarfCompileUnit.hpp
@@ -357,6 +357,10 @@ class CompileUnit {
   /// constructVariableDIE - Construct a DIE for the given DbgVariable.
   DIE *constructVariableDIE(DbgVariable &DV, bool isScopeAbstract);
 
+  /// Apply attributes for DIE created in constructVariableDIE
+  void applyVariableAttributes(DbgVariable &DV, DIE *VariableDie, bool isScopeAbstract,
+                               DIE *AbsDIE = nullptr);
+
   /// Create a DIE with the given Tag, add the DIE to its parent, and
   /// call insertDIE if MD is not null.
   DIE *createAndAddDIE(unsigned Tag, DIE &Parent, llvm::DINode *N = nullptr);
diff --git a/IGC/DebugInfo/DwarfDebug.cpp b/IGC/DebugInfo/DwarfDebug.cpp
@@ -675,7 +675,6 @@ DIE *DwarfDebug::createScopeChildrenDIE(CompileUnit *TheCU, LexicalScope *Scope,
   DIE *ObjectPointer = NULL;
 
   SmallVector<DbgVariable *, 8> dbgVariables;
-
   // Collect arguments for current function.
   if (LScopes.isCurrentFunctionScope(Scope)) {
     std::copy(CurrentFnArguments.begin(), CurrentFnArguments.end(), std::back_inserter(dbgVariables));
@@ -687,15 +686,23 @@ DIE *DwarfDebug::createScopeChildrenDIE(CompileUnit *TheCU, LexicalScope *Scope,
     std::copy(Variables.begin(), Variables.end(), std::back_inserter(dbgVariables));
   }
 
-  // Collect all argument/variable children
+  // Create and collect all argument/variable children
   for (DbgVariable *ArgDV : dbgVariables) {
     if (!ArgDV)
       continue;
-    if (DIE *Arg = TheCU->constructVariableDIE(*ArgDV, Scope->isAbstractScope())) {
-      Children.push_back(Arg);
-      if (ArgDV->isObjectPointer())
-        ObjectPointer = Arg;
-    }
+    DIE *Arg = TheCU->constructVariableDIE(*ArgDV, Scope->isAbstractScope());
+    Children.push_back(Arg);
+    if (ArgDV->isObjectPointer())
+      ObjectPointer = Arg;
+  }
+
+  // Apply attributes to each created DIE. It needs to be done after creating all
+  // subprogram DIEs, beacuse we might need reference to them in addType() function.
+  for (DbgVariable *ArgDV : dbgVariables) {
+    if (!ArgDV)
+      continue;
+    if (DIE *VarDIE = TheCU->getDIE(const_cast<DILocalVariable*>(ArgDV->getVariable())))
+      TheCU->applyVariableAttributes(*ArgDV, VarDIE, Scope->isAbstractScope());
   }
 
   // There is no need to emit empty lexical block DIE.
@@ -1158,9 +1165,11 @@ void DwarfDebug::collectDeadVariables() {
         if (!isa<DILocalVariable>(DV))
           continue;
         DbgVariable NewVar(cast<DILocalVariable>(DV));
-        if (DIE *VariableDIE = SPCU->constructVariableDIE(NewVar, false)) {
-          SPDIE->addChild(VariableDIE);
+        DIE *VariableDIE = SPCU->constructVariableDIE(NewVar, false);
+        if (SPCU->getDIE(const_cast<DILocalVariable*>(NewVar.getVariable()))) {
+          SPCU->applyVariableAttributes(NewVar, VariableDIE, false);
         }
+        SPDIE->addChild(VariableDIE);
       }
     }
 
diff --git a/IGC/ocloc_tests/DebugInfo/generate-string-length-type-field.ll b/IGC/ocloc_tests/DebugInfo/generate-string-length-type-field.ll
@@ -0,0 +1,58 @@
+;=========================== begin_copyright_notice ============================
+;
+; Copyright (C) 2025 Intel Corporation
+;
+; SPDX-License-Identifier: MIT
+;
+;============================ end_copyright_notice =============================
+
+; Test checks if DW_AT_string_length is correctly generated for
+; vla fortran string array (DIStringType)
+
+; UNSUPPORTED: sys32
+
+; REQUIRES: regkeys, oneapi-readelf, llvm-14-plus, dg2-supported
+
+; RUN: llvm-as -opaque-pointers=0 %s -o %t
+; RUN: ocloc compile -llvm_input -file %t -device dg2 -options "-g -cl-opt-disable -igc_opts 'ElfDumpEnable=1, DumpUseShorterName=0, DebugDumpNamePrefix=%t_'"
+; RUN: oneapi-readelf --debug-dump %t_OCL_simd8_foo.elf | FileCheck %s
+
+; CHECK:   DW_AT_name        : vla_string
+; CHECK:   DW_AT_type        : {{.*}}
+
+; CHECK: <{{[0-9]+}}><[[LENGHT:[0-9a-f]+]]>: Abbrev Number: [[#]] (DW_TAG_variable)
+; CHECK-NEXT:   DW_AT_name        : vla_string.len
+
+; CHECK:   DW_AT_name        : vla_string.type
+; CHECK:   DW_AT_string_length: <0x[[LENGHT]]>
+
+define spir_func void @subprgm() #0 {
+entry:
+  ret void, !dbg !13
+}
+
+define spir_kernel void @foo() #0 {
+entry:
+  call void @subprgm()
+  ret void
+}
+
+attributes #0 = { noinline nounwind optnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!1, !2}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_Fortran95, file: !3, producer: "Intel(R) Fortran 24.0-1640", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, retainedTypes: !4, globals: !4, imports: !4)
+!1 = !{i32 7, !"Dwarf Version", i32 4}
+!2 = !{i32 2, !"Debug Info Version", i32 3}
+!3 = !DIFile(filename: "simple-string-type.f90", directory: "/")
+!4 = !{}
+!5 = distinct !DISubprogram(name: "subprgm", scope: !3, file: !3, line: 256, type: !6, scopeLine: 256, unit: !0, retainedNodes: !8)
+!6 = !DISubroutineType(types: !7)
+!7 = !{null}
+!8 = !{!9, !11}
+!9 = !DILocalVariable(name: "vla_string.len", scope: !5, type: !10, flags: DIFlagArtificial)
+!10 = !DIBasicType(name: "integer*8", size: 64, encoding: DW_ATE_signed)
+!11 = !DILocalVariable(name: "vla_string", arg: 1, scope: !5, file: !3, line: 256, type: !12)
+!12 = !DIStringType(name: "vla_string.type", stringLength: !9)
+!13 = !DILocation(line: 1, column: 2, scope: !5)
diff --git a/IGC/ocloc_tests/DebugInfo/generate-string-type-field.ll b/IGC/ocloc_tests/DebugInfo/generate-string-type-field.ll
@@ -0,0 +1,53 @@
+;=========================== begin_copyright_notice ============================
+;
+; Copyright (C) 2024 Intel Corporation
+;
+; SPDX-License-Identifier: MIT
+;
+;============================ end_copyright_notice =============================
+
+; Test whether DW_TAG_string_type is generated in DWARF
+
+; UNSUPPORTED: sys32
+
+; REQUIRES: regkeys, oneapi-readelf, dg2-supported
+
+; RUN: llvm-as -opaque-pointers=0 %s -o %t
+; RUN: ocloc compile -llvm_input -file %t -device dg2 -options "-g -cl-opt-disable -igc_opts 'ElfDumpEnable=1, DumpUseShorterName=0, DebugDumpNamePrefix=%t_'"
+; RUN: oneapi-readelf --debug-dump %t_OCL_simd32_foo.elf | FileCheck %s
+
+; CHECK: DW_TAG_string_type
+; CHECK:   DW_AT_name        : character(*)
+; CHECK: DW_TAG_string_type
+; CHECK:   DW_AT_name        : character(10)
+; CHECK:   DW_AT_byte_size   : 10
+; CHECK: DW_TAG_string_type
+; CHECK:   DW_AT_name        : character
+; CHECK:   DW_AT_encoding    : 0    (void)
+; CHECK:   DW_AT_byte_size   : 0
+
+; Function Attrs: noinline nounwind optnone
+define spir_kernel void @foo() #0 {
+entry:
+  ret void
+}
+
+attributes #0 = { noinline nounwind optnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!1, !2}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_Fortran95, file: !3, producer: "Intel(R) Fortran 24.0-1640", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, retainedTypes: !5, globals: !4, imports: !4)
+!1 = !{i32 7, !"Dwarf Version", i32 4}
+!2 = !{i32 2, !"Debug Info Version", i32 3}
+!3 = !DIFile(filename: "simple-string-type.f90", directory: "/")
+!4 = !{}
+!5 = !{!6, !9, !12, !13}
+!6 = !DIStringType(name: "character(*)", stringLength: !7, stringLengthExpression: !DIExpression(), size: 32)
+!7 = !DILocalVariable(arg: 2, scope: !8, file: !3, line: 256, type: !11, flags: DIFlagArtificial)
+!8 = distinct !DISubprogram(name: "subprgm", scope: !0, file: !3, line: 256, type: !9, isLocal: false, isDefinition: true, scopeLine: 256, isOptimized: false, unit: !0)
+!9 = !DISubroutineType(types: !10)
+!10 = !{null, !6, !11}
+!11 = !DIBasicType(name: "integer*8", size: 64, align: 64, encoding: DW_ATE_signed)
+!12 = !DIStringType(name: "character(10)", size: 80, align: 8)
+!13 = !DIBasicType(tag: DW_TAG_string_type, name: "character")
