DebugInfoVerifier: Verify dwo units

Initial pass - follow-up patches to address various limitations (debug
ranges, location lists... )

Author: dwblaikie

llvm/include/llvm/DebugInfo/DWARF/DWARFContext.h

@@ -189,6 +189,11 @@ class DWARFContext : public DIContext {
                                DWOUnits.begin() + DWOUnits.getNumInfoUnits());
   }
 
+  const DWARFUnitVector &getDWOUnitsVector() {
+    parseDWOUnits();
+    return DWOUnits;
+  }
+
   /// Get units from .debug_types.dwo in the DWO context.
   unit_iterator_range dwo_types_section_units() {
     parseDWOUnits();

llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp

@@ -390,6 +390,9 @@ bool DWARFVerifier::handleDebugInfo() {
 
   OS << "Verifying non-dwo Units...\n";
   NumErrors += verifyUnits(DCtx.getNormalUnitsVector());
+
+  OS << "Verifying dwo Units...\n";
+  NumErrors += verifyUnits(DCtx.getDWOUnitsVector());
   return NumErrors == 0;
 }
 

llvm/test/DebugInfo/X86/skeleton-unit-verify.s

@@ -8,6 +8,7 @@
 # CHECK-NEXT: warning: DW_TAG_skeleton_unit has DW_CHILDREN_yes but DIE has no children
 # CHECK-NEXT: DW_TAG_skeleton_unit
 # CHECK-NEXT: error: Skeleton compilation unit has children.
+# CHECK-NEXT: Verifying dwo Units...
 # CHECK-NEXT: Errors detected.
 
         .section .debug_abbrev,"",@progbits

llvm/test/tools/llvm-dwarfdump/X86/verify_split_cu.s

@@ -0,0 +1,18 @@
+# RUN: llvm-mc %s -filetype obj -triple x86_64-linux-gnu -o - \
+# RUN: | not llvm-dwarfdump -v -verify - \
+# RUN: | FileCheck %s --implicit-check-not=error --implicit-check-not=warning
+
+# CHECK: Verifying dwo Units...
+# CHECK: error: Compilation unit root DIE is not a unit DIE: DW_TAG_null.
+# CHECK: error: Compilation unit type (DW_UT_split_compile) and root DIE (DW_TAG_null) do not match.
+# CHECK: Errors detected
+	.section	.debug_info.dwo,"e",@progbits
+	.long	.Ldebug_info_dwo_end1-.Ldebug_info_dwo_start1 # Length of Unit
+.Ldebug_info_dwo_start1:
+	.short	5                               # DWARF version number
+	.byte	5                               # DWARF Unit Type
+	.byte	8                               # Address Size (in bytes)
+	.long	0                               # Offset Into Abbrev. Section
+	.quad	5527374834836270265
+	.byte	0                               # End Of Children Mark
+.Ldebug_info_dwo_end1: