[llvm-bugs] [Bug 45485] New: llvm-dwarfdump fails to dump debug_frame info because of empty CIEs in the section

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=45485

            Bug ID: 45485
           Summary: llvm-dwarfdump fails to dump debug_frame info because
                    of empty CIEs in the section
           Product: tools
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: llvm-dwarfdump
          Assignee: unassignedbugs at nondot.org
          Reporter: cdenizet at mozilla.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 23338
  --> https://bugs.llvm.org/attachment.cgi?id=23338&action=edit
Elf file with the guilty section

A firefox library (libxul.so) contains some zero at beginning of the section
.debug_frame:

readelf -x .debug_frame libxul.so | head -10
Hex dump of section '.debug_frame':
  0x00000000 00000000 00000000 00000000 00000000 ................
  0x00000010 00000000 00000000 00000000 00000000 ................
  0x00000020 00000000 00000000 00000000 00000000 ................
  0x00000030 00000000 00000000 00000000 00000000 ................
  0x00000040 00000000 00000000 00000000 00000000 ................
  0x00000050 00000000 00000000 00000000 00000000 ................
  0x00000060 00000000 00000000 00000000 00000000 ................
  0x00000070 00000000 00000000 14000000 ffffffff ................

So I compiled it using -Wl,-Map,map and I get in the map file:
             VMA              LMA     Size Align Out     In      Symbol
               0                0     84d8     8 .debug_frame
               0                0        4     8        
../../../media/libdav1d/asm/cdef.o:(.debug_frame)
               8                8        4     8        
../../../media/libdav1d/asm/cdef_sse.o:(.debug_frame)
              10               10        4     8        
../../../media/libdav1d/asm/cpuid.o:(.debug_frame)
              18               18        4     8        
../../../media/libdav1d/asm/film_grain.o:(.debug_frame)
              20               20        4     8        
../../../media/libdav1d/asm/ipred.o:(.debug_frame)
              28               28        4     8        
../../../media/libdav1d/asm/ipred_ssse3.o:(.debug_frame)
              30               30        4     8        
../../../media/libdav1d/asm/itx.o:(.debug_frame)
              38               38        4     8        
../../../media/libdav1d/asm/itx_ssse3.o:(.debug_frame)
              40               40        4     8        
../../../media/libdav1d/asm/loopfilter.o:(.debug_frame)
              48               48        4     8        
../../../media/libdav1d/asm/loopfilter_ssse3.o:(.debug_frame)
              50               50        4     8        
../../../media/libdav1d/asm/looprestoration.o:(.debug_frame)
              58               58        4     8        
../../../media/libdav1d/asm/looprestoration_ssse3.o:(.debug_frame)
              60               60        4     8        
../../../media/libdav1d/asm/mc.o:(.debug_frame)
              68               68        4     8        
../../../media/libdav1d/asm/mc_ssse3.o:(.debug_frame)
              70               70        4     8        
../../../media/libdav1d/asm/msac.o:(.debug_frame)
              78               78      c58     8        
/home/calixte/dev/mozilla/mozilla-central.hg/obj-x86_64-pc-linux-gnu/x86_64-unknown-linux-gnu/release/libgkrust.a(tinystr-42ea65f827942861.tinystr.2dk5ccm8-cgu.0.rcgu.o):(.debug_frame)

These zeros correspond to empty CIEs and should be just skipped.

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