[PATCH] D71931: [DWARF] Allow empty address range tables.

[Igor Kudrin via Phabricator via llvm-commits]

ikudrin created this revision.
ikudrin added reviewers: bkramer, dblaikie, probinson, aprantl, zturner.
ikudrin added projects: debug-info, LLVM.
Herald added a subscriber: hiraditya.

Empty address range tables are not prohibited by the DWARF standard. Supporting them makes the code a bit simpler.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D71931

Files:
  llvm/lib/DebugInfo/DWARF/DWARFDebugArangeSet.cpp
  llvm/test/DebugInfo/X86/dwarfdump-debug-aranges.s


Index: llvm/test/DebugInfo/X86/dwarfdump-debug-aranges.s
===================================================================
--- /dev/null
+++ llvm/test/DebugInfo/X86/dwarfdump-debug-aranges.s
@@ -0,0 +1,25 @@
+# RUN: llvm-mc -triple x86_64-unknown-linux %s -filetype=obj -o - | \
+# RUN:  llvm-dwarfdump -debug-aranges - 2>&1 | \
+# RUN:  FileCheck %s
+
+    .section .debug_aranges,"", at progbits
+# CHECK: .debug_aranges contents:
+
+## Check that an empty set of ranges is supported.
+.L1:
+    .long   .L1end - .L1version     # Length
+# CHECK: Address Range Header: length = 0x00000014,
+.L1version:
+    .short  2                       # Version
+    .long   0x3456789a              # Debug Info Offset
+    .byte   4                       # Address Size
+    .byte   0                       # Segment Selector Size
+# CHECK-SAME: version = 0x0002,
+# CHECK-SAME: cu_offset = 0x3456789a,
+# CHECK-SAME: addr_size = 0x04,
+# CHECK-SAME: seg_size = 0x00
+    .space  7 - (. - .L1 + 7) % 8   # Padding
+.L1tuples:
+    .long   0, 0                    # Termination tuple
+# CHECK-NOT: [0x
+.L1end:
Index: llvm/lib/DebugInfo/DWARF/DWARFDebugArangeSet.cpp
===================================================================
--- llvm/lib/DebugInfo/DWARF/DWARFDebugArangeSet.cpp
+++ llvm/lib/DebugInfo/DWARF/DWARFDebugArangeSet.cpp
@@ -90,10 +90,10 @@
       if (arangeDescriptor.Address || arangeDescriptor.Length)
         ArangeDescriptors.push_back(arangeDescriptor);
       else
-        break; // We are done if we get a zero address and length
+        return true; // We are done if we get a zero address and length
     }
 
-    return !ArangeDescriptors.empty();
+    return false; // No termination tuple is found.
   }
   return false;
 }


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