[llvm] r319564 - [DebugInfo] Bail out if making no progress dumping line tables.

[Paul Robinson via llvm-commits]

Author: probinson
Date: Fri Dec  1 10:25:30 2017
New Revision: 319564

URL: http://llvm.org/viewvc/llvm-project?rev=319564&view=rev
Log:
[DebugInfo] Bail out if making no progress dumping line tables.

Modified:
    llvm/trunk/lib/DebugInfo/DWARF/DWARFContext.cpp
    llvm/trunk/test/DebugInfo/X86/dwarfdump-bogus-LNE.s

Modified: llvm/trunk/lib/DebugInfo/DWARF/DWARFContext.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/DebugInfo/DWARF/DWARFContext.cpp?rev=319564&r1=319563&r2=319564&view=diff
==============================================================================
--- llvm/trunk/lib/DebugInfo/DWARF/DWARFContext.cpp (original)
+++ llvm/trunk/lib/DebugInfo/DWARF/DWARFContext.cpp Fri Dec  1 10:25:30 2017
@@ -357,12 +357,16 @@ void DWARFContext::dump(
       // Verbose dumping is done during parsing and not on the intermediate
       // representation.
       OS << "debug_line[" << format("0x%8.8x", Offset) << "]\n";
+      unsigned OldOffset = Offset;
       if (DumpOpts.Verbose) {
         LineTable.parse(LineData, &Offset, U, &OS);
       } else {
         LineTable.parse(LineData, &Offset, U);
         LineTable.dump(OS);
       }
+      // Check for unparseable prologue, to avoid infinite loops.
+      if (OldOffset == Offset)
+        break;
     }
   }
 

Modified: llvm/trunk/test/DebugInfo/X86/dwarfdump-bogus-LNE.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/dwarfdump-bogus-LNE.s?rev=319564&r1=319563&r2=319564&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/dwarfdump-bogus-LNE.s (original)
+++ llvm/trunk/test/DebugInfo/X86/dwarfdump-bogus-LNE.s Fri Dec  1 10:25:30 2017
@@ -150,3 +150,100 @@ LT2_end:
 
 # ERR:      Unexpected line op length at offset 0x0000005e
 # ERR-SAME: expected 0x02 found 0x01
+
+# The above parsing errors still let us move to the next unit.
+# If the prologue is bogus, we need to bail out because we can't
+# even find the next unit.
+
+# DWARF v4 line-table header #3.
+LT3_start:
+        .long   LT3_end-LT3_version   # Length of Unit (DWARF-32 format)
+LT3_version:
+        .short  4               # DWARF version number
+        .long   LT3_header_end-LT3_params   # Length of Prologue
+LT3_params:
+        .byte   1               # Minimum Instruction Length
+        .byte   1               # Maximum Operations per Instruction
+        .byte   1               # Default is_stmt
+        .byte   -5              # Line Base
+        .byte   14              # Line Range
+        .byte   13              # Opcode Base
+        .byte   0               # Standard Opcode Lengths
+        .byte   1
+        .byte   1
+        .byte   1
+        .byte   1
+        .byte   0
+        .byte   0
+        .byte   0
+        .byte   1
+        .byte   0
+        .byte   0
+        .byte   1
+        # No directories.
+        .byte   0
+        # No files.
+        .byte   0
+        # Extra junk at the end of the prologue, so the length isn't right.
+        .long   0
+LT3_header_end:
+        # Real opcode and operand.
+        .byte   0
+        .byte   9
+        .byte   2               # DW_LNE_set_address
+        .quad   .text
+        # Real opcode with incorrect length.
+        .byte   0
+        .byte   2               # Wrong length, should be 1.
+        .byte   1               # DW_LNE_end_sequence
+LT3_end:
+
+# We should have bailed out above, so never see this in the dump.
+# DWARF v4 line-table header #4.
+LT4_start:
+        .long   LT4_end-LT4_version   # Length of Unit (DWARF-32 format)
+LT4_version:
+        .short  4               # DWARF version number
+        .long   LT4_header_end-LT4_params   # Length of Prologue
+LT4_params:
+        .byte   1               # Minimum Instruction Length
+        .byte   1               # Maximum Operations per Instruction
+        .byte   1               # Default is_stmt
+        .byte   -5              # Line Base
+        .byte   14              # Line Range
+        .byte   13              # Opcode Base
+        .byte   0               # Standard Opcode Lengths
+        .byte   1
+        .byte   1
+        .byte   1
+        .byte   1
+        .byte   0
+        .byte   0
+        .byte   0
+        .byte   1
+        .byte   0
+        .byte   0
+        .byte   1
+        # No directories.
+        .byte   0
+        # No files.
+        .byte   0
+LT4_header_end:
+        # Real opcode and operand.
+        .byte   0
+        .byte   9
+        .byte   2               # DW_LNE_set_address
+        .quad   .text
+        # Real opcode with correct length.
+        .byte   0
+        .byte   1
+        .byte   1               # DW_LNE_end_sequence
+LT4_end:
+
+# Look for the dump of unit 3, and don't want unit 4.
+# CHECK:     Line table prologue:
+# CHECK-NOT: Line table prologue:
+
+# And look for the error message.
+# ERR:      warning: parsing line table prologue at 0x0000005f should have
+# ERR-SAME: ended at 0x00000081 but it ended at 0x0000007d