Add regression test for recursive DWO references

Adds a test case simulating a self-referential DWO file to ensure
recursion is handled gracefully without crashing.

See #476

Author: EricRahm

tests/dwarf/debug_info/recursive-dwo.test

@@ -0,0 +1,121 @@
+# Tests that we handle recursive DWO references gracefully without crashing.
+# This reproduces a case where a .dwo file contains a DW_AT_GNU_dwo_name attribute pointing to itself.
+
+# RUN: mkdir -p %t.dir
+# RUN: %yaml2obj %s --docnum=1 -o %t.dir/skeleton.o
+# RUN: %yaml2obj %s --docnum=2 -o %t.dir/recursive.dwo
+
+# Run bloaty from the directory containing the files so relative paths resolve.
+# RUN: cd %t.dir && %bloaty -d compileunits skeleton.o | %FileCheck %s
+
+# If the recursion guard is working, bloaty should read the DWO once,
+# resolve the CU name "recursive.c", and stop. It should NOT crash.
+
+# CHECK:      FILE SIZE        VM SIZE    
+# CHECK:   --------------  -------------- 
+# CHECK:    [ELF Section Headers]
+# CHECK:    recursive.c
+# CHECK:    TOTAL
+
+# Document 1: skeleton.o
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_DYN
+  Machine:         EM_X86_64
+ProgramHeaders:
+  - Type:            PT_LOAD
+    Flags:           [ PF_X, PF_R ]
+    FirstSec:        .text
+    LastSec:         .text
+    VAddr:           0x400000
+    Align:           0x1000
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x400000
+    AddressAlign:    0x10
+    Size:            0x100
+  - Name:            .debug_addr
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x1
+    Content: '0000400000000000'
+DWARF:
+  debug_str:
+    - recursive.dwo
+    - .
+  debug_abbrev:
+    - ID:              0
+      Table:
+        - Code:            0x1
+          Tag:             DW_TAG_compile_unit
+          Children:        DW_CHILDREN_no
+          Attributes:
+            - Attribute:       DW_AT_GNU_dwo_name
+              Form:            DW_FORM_strp
+            - Attribute:       DW_AT_comp_dir
+              Form:            DW_FORM_strp
+            - Attribute:       DW_AT_GNU_dwo_id
+              Form:            DW_FORM_data8
+            - Attribute:       DW_AT_GNU_addr_base
+              Form:            DW_FORM_sec_offset
+  debug_info:
+    - Version:         4
+      AbbrevTableID:   0
+      AbbrOffset:      0x0
+      AddrSize:        8
+      Entries:
+        - AbbrCode:        0x1
+          Values:
+            - Value:           0x0  # recursive.dwo
+            - Value:           0xe  # .
+            - Value:           0xfeedfacefeedface
+            - Value:           0x0
+
+# Document 2: recursive.dwo
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+DWARF:
+  debug_str:
+    - recursive.c
+    - recursive.dwo
+    - .
+  debug_abbrev:
+    - ID:              0
+      Table:
+        - Code:            0x1
+          Tag:             DW_TAG_compile_unit
+          Children:        DW_CHILDREN_no
+          Attributes:
+            - Attribute:       DW_AT_name
+              Form:            DW_FORM_strp
+            - Attribute:       DW_AT_GNU_dwo_id
+              Form:            DW_FORM_data8
+            - Attribute:       DW_AT_GNU_dwo_name
+              Form:            DW_FORM_strp
+            - Attribute:       DW_AT_comp_dir
+              Form:            DW_FORM_strp
+            - Attribute:       DW_AT_low_pc
+              Form:            DW_FORM_GNU_addr_index
+            - Attribute:       DW_AT_high_pc
+              Form:            DW_FORM_data4
+  debug_info:
+    - Version:         4
+      AbbrevTableID:   0
+      AbbrOffset:      0x0
+      AddrSize:        8
+      Entries:
+        - AbbrCode:        0x1
+          Values:
+            - Value:           0x0  # recursive.c
+            - Value:           0xfeedfacefeedface
+            - Value:           0xc  # recursive.dwo
+            - Value:           0x1a # .
+            - Value:           0x0  # low_pc index 0 -> 0x400000
+            - Value:           0x100 # high_pc size -> 0x100