DebugInfo: reduce DIE range verification on object files

Relocatable content may have overlapping ranges until the sections are
finalized.  This reduces the amount of verification that is done on an object
file so that invalid errors are not raised.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@345441 91177308-0d34-0410-b5e6-96231b3b80d8

Author: compnerd

include/llvm/DebugInfo/DWARF/DWARFVerifier.h

@@ -97,6 +97,9 @@ class DWARFVerifier {
   /// lies between to valid DIEs.
   std::map<uint64_t, std::set<uint32_t>> ReferenceToDIEOffsets;
   uint32_t NumDebugLineErrors = 0;
+  // Used to relax some checks that do not currently work portably
+  bool IsObjectFile;
+  bool IsMachOObject;
 
   raw_ostream &error() const;
   raw_ostream &warn() const;
@@ -286,8 +289,8 @@ class DWARFVerifier {
 
 public:
   DWARFVerifier(raw_ostream &S, DWARFContext &D,
-                DIDumpOptions DumpOpts = DIDumpOptions::getForSingleDIE())
-      : OS(S), DCtx(D), DumpOpts(std::move(DumpOpts)) {}
+                DIDumpOptions DumpOpts = DIDumpOptions::getForSingleDIE());
+
   /// Verify the information in any of the following sections, if available:
   /// .debug_abbrev, debug_abbrev.dwo
   ///

lib/DebugInfo/DWARF/DWARFVerifier.cpp

@@ -379,20 +379,42 @@ unsigned DWARFVerifier::verifyDieRanges(const DWARFDie &Die,
   // Build RI for this DIE and check that ranges within this DIE do not
   // overlap.
   DieRangeInfo RI(Die);
-  for (auto Range : Ranges) {
-    if (!Range.valid()) {
-      ++NumErrors;
-      error() << "Invalid address range " << Range << "\n";
-      continue;
-    }
 
-    // Verify that ranges don't intersect.
-    const auto IntersectingRange = RI.insert(Range);
-    if (IntersectingRange != RI.Ranges.end()) {
-      ++NumErrors;
-      error() << "DIE has overlapping address ranges: " << Range << " and "
-              << *IntersectingRange << "\n";
-      break;
+  // TODO support object files better
+  //
+  // Some object file formats (i.e. non-MachO) support COMDAT.  ELF in
+  // particular does so by placing each function into a section.  The DWARF data
+  // for the function at that point uses a section relative DW_FORM_addrp for
+  // the DW_AT_low_pc and a DW_FORM_data4 for the offset as the DW_AT_high_pc.
+  // In such a case, when the Die is the CU, the ranges will overlap, and we
+  // will flag valid conflicting ranges as invalid.
+  //
+  // For such targets, we should read the ranges from the CU and partition them
+  // by the section id.  The ranges within a particular section should be
+  // disjoint, although the ranges across sections may overlap.  We would map
+  // the child die to the entity that it references and the section with which
+  // it is associated.  The child would then be checked against the range
+  // information for the associated section.
+  //
+  // For now, simply elide the range verification for the CU DIEs if we are
+  // processing an object file.
+
+  if (!IsObjectFile || IsMachOObject || Die.getTag() == DW_TAG_subprogram) {
+    for (auto Range : Ranges) {
+      if (!Range.valid()) {
+        ++NumErrors;
+        error() << "Invalid address range " << Range << "\n";
+        continue;
+      }
+
+      // Verify that ranges don't intersect.
+      const auto IntersectingRange = RI.insert(Range);
+      if (IntersectingRange != RI.Ranges.end()) {
+        ++NumErrors;
+        error() << "DIE has overlapping address ranges: " << Range << " and "
+                << *IntersectingRange << "\n";
+        break;
+      }
     }
   }
 
@@ -721,6 +743,15 @@ void DWARFVerifier::verifyDebugLineRows() {
   }
 }
 
+DWARFVerifier::DWARFVerifier(raw_ostream &S, DWARFContext &D,
+                             DIDumpOptions DumpOpts)
+    : OS(S), DCtx(D), DumpOpts(std::move(DumpOpts)) {
+  if (const auto *F = DCtx.getDWARFObj().getFile()) {
+    IsObjectFile = F->isRelocatableObject();
+    IsMachOObject = F->isMachO();
+  }
+}
+
 bool DWARFVerifier::handleDebugLine() {
   NumDebugLineErrors = 0;
   OS << "Verifying .debug_line...\n";

test/tools/llvm-dwarfdump/X86/debug-verify-object.s

@@ -0,0 +1,57 @@
+# RUN: llvm-mc -filetype obj -o - %s | llvm-dwarfdump --verify -
+
+	.text
+
+	.section	.text.f,"ax",@progbits
+	.globl	f
+	.type	f,@function
+f:
+.Lfunc_begin0:
+	pushq	$32
+	popq	%rax
+	retq
+.Lfunc_end0:
+	.size	f, .Lfunc_end0-f
+
+	.section	.text.g,"ax",@progbits
+	.globl	g
+	.type	g,@function
+g:
+.Lfunc_begin1:
+	pushq   $64
+	popq    %rax
+	retq
+.Lfunc_end1:
+	.size	g, .Lfunc_end1-g
+
+	.section	.debug_abbrev,"",@progbits
+	.byte	1                       # Abbreviation Code
+	.byte	17                      # DW_TAG_compile_unit
+	.byte	0                       # DW_CHILDREN_no
+	.byte	17                      # DW_AT_low_pc
+	.byte	1                       # DW_FORM_addr
+	.byte	85                      # DW_AT_ranges
+	.byte	23                      # DW_FORM_sec_offset
+	.byte	0                       # EOM(1)
+	.byte	0                       # EOM(2)
+	.byte	0                       # EOM(3)
+
+	.section	.debug_info,"",@progbits
+.Lcu_begin0:
+	.long	20                      # Length of Unit
+	.short	4                       # DWARF version number
+	.long	.debug_abbrev           # Offset Into Abbrev. Section
+	.byte	8                       # Address Size (in bytes)
+	.byte	1                       # Abbrev [1] 0xb:0x1f DW_TAG_compile_unit
+	.quad	0                       # DW_AT_low_pc
+	.long	.Ldebug_ranges0         # DW_AT_ranges
+
+	.section        .debug_ranges,"",@progbits
+.Ldebug_ranges0:
+	.quad	.Lfunc_begin0
+	.quad	.Lfunc_end0
+	.quad	.Lfunc_begin1
+	.quad	.Lfunc_end1
+	.quad	0
+	.quad	0
+