[PATCH] D52223: [dwarfdump] Verify DW_AT_type.

[Jonas Devlieghere via Phabricator via llvm-commits]

JDevlieghere created this revision.
JDevlieghere added reviewers: aprantl, dblaikie, probinson.
JDevlieghere added a project: debug-info.
Herald added a subscriber: hiraditya.
JDevlieghere added a dependency: D38719: [llvm-dwarfdump] Verify compatible TAG for attributes..

This extends the verifier to catch three new errors:

1. Missing DW_AT_type attributes for DW_TAG_formal_parameter, DW_TAG_variable and DW_TAG_array_type.
2. Invalid references for DW_AT_type attribute values. Technically we already detect invalid references, but now we can be more specific.
3. Valid references for DW_AT_type pointing to a non-type tag.


Repository:
  rL LLVM

https://reviews.llvm.org/D52223

Files:
  llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp
  llvm/test/tools/llvm-dwarfdump/X86/verify_debug_info.s


Index: llvm/test/tools/llvm-dwarfdump/X86/verify_debug_info.s
===================================================================
--- llvm/test/tools/llvm-dwarfdump/X86/verify_debug_info.s
+++ llvm/test/tools/llvm-dwarfdump/X86/verify_debug_info.s
@@ -11,6 +11,24 @@
 # CHECK-NEXT: DW_AT_comp_dir [DW_FORM_strp]	( .debug_str[0x0000003f] = "/Users/sgravani/Development/tests")
 # CHECK-NEXT: DW_AT_low_pc [DW_FORM_addr]	(0x0000000000000000)
 # CHECK-NEXT: DW_AT_high_pc [DW_FORM_data4]	(0x00000016){{[[:space:]]}}
+# CHECK-NEXT: error: DIE has DW_AT_type with incompatible tag DW_TAG_null{{[[:space:]]}}
+# CHECK-NEXT: 0x0000002b: DW_TAG_subprogram [2] *
+# CHECK-NEXT: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
+# CHECK-NEXT: DW_AT_high_pc [DW_FORM_data4]     (0x00000016)
+# CHECK-NEXT: DW_AT_frame_base [DW_FORM_exprloc]        (DW_OP_reg6)
+# CHECK-NEXT: DW_AT_name [DW_FORM_strp] ( .debug_str[0x00000061] = "main")
+# CHECK-NEXT: DW_AT_decl_file [DW_FORM_data1]   (0x01)
+# CHECK-NEXT: DW_AT_decl_line [DW_FORM_data1]   (1)
+# CHECK-NEXT: DW_AT_prototyped [DW_FORM_flag_present]   (true)
+# CHECK-NEXT: DW_AT_type [DW_FORM_ref4] (cu + 0x0052 => {0x00000052} "")
+# CHECK-NEXT: DW_AT_external [DW_FORM_flag_present]     (true){{[[:space:]]}}
+# CHECK-NEXT: error: DIE with tag DW_TAG_variable is missing type attribute:{{[[:space:]]}}
+# CHECK-NEXT: 0x00000044: DW_TAG_variable
+# CHECK-NEXT: DW_AT_location    (DW_OP_fbreg -8)
+# CHECK-NEXT: DW_AT_name        ("a")
+# CHECK-NEXT: DW_AT_decl_file   (0x01)
+# CHECK-NEXT: DW_AT_decl_line   (2)
+# CHECK-NEXT: DW_AT_use_location        (0x00000053){{[[:space:]]}}
 # CHECK-NEXT: error: Compilation unit root DIE is not a unit DIE: DW_TAG_null.
 # CHECK-NEXT: error: Compilation unit type (DW_UT_compile) and root DIE (DW_TAG_null) do not match.
 # CHECK-NEXT: error: Units[2] - start offset: 0x00000068
@@ -107,7 +125,7 @@
 	.byte	11                      ## DW_FORM_data1
 	.byte	59                      ## DW_AT_decl_line
 	.byte	11                      ## DW_FORM_data1
-	.byte	73                      ## DW_AT_type
+	.byte	74                      ## DW_AT_type
 	.byte	19                      ## DW_FORM_ref4
 	.byte	0                       ## EOM(1)
 	.byte	0                       ## EOM(2)
@@ -152,7 +170,7 @@
 	.byte	1                       ## DW_AT_decl_file
 	.byte	1                       ## DW_AT_decl_line
                                         ## DW_AT_prototyped
-	.long	83                      ## DW_AT_type
+	.long	82                      ## DW_AT_type
                                         ## DW_AT_external
 	.byte	3                       ## Abbrev [3] 0x44:0xe DW_TAG_variable
 	.byte	2                       ## DW_AT_location
Index: llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp
===================================================================
--- llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp
+++ llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp
@@ -176,11 +176,25 @@
   unsigned NumDies = Unit.getNumDIEs();
   for (unsigned I = 0; I < NumDies; ++I) {
     auto Die = Unit.getDIEAtIndex(I);
+
     if (Die.getTag() == DW_TAG_null)
       continue;
+
+    bool HasTypeAttr = false;
     for (auto AttrValue : Die.attributes()) {
       NumUnitErrors += verifyDebugInfoAttribute(Die, AttrValue);
       NumUnitErrors += verifyDebugInfoForm(Die, AttrValue);
+      HasTypeAttr |= (AttrValue.Attr == DW_AT_type);
+    }
+
+    if (!HasTypeAttr && (Die.getTag() == DW_TAG_formal_parameter ||
+                         Die.getTag() == DW_TAG_variable ||
+                         Die.getTag() == DW_TAG_array_type)) {
+      error() << "DIE with tag " << TagString(Die.getTag())
+              << " is missing type attribute:\n";
+      Die.dump(OS, 0);
+      OS << '\n';
+      NumUnitErrors++;
     }
   }
 
@@ -470,6 +484,18 @@
                   TagString(RefTag));
     }
   }
+  case DW_AT_type: {
+    DWARFDie TypeDie = Die.getAttributeValueAsReferencedDie(DW_AT_type);
+    if (!TypeDie) {
+      ReportError("DIE has invalid type attribute");
+      break;
+    }
+    if (!isType(TypeDie.getTag())) {
+      ReportError("DIE has " + AttributeString(Attr) +
+                  " with incompatible tag " + TagString(TypeDie.getTag()));
+      break;
+    }
+  }
   default:
     break;
   }


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