[Bug target/59363] [4.9 Regression] r203886 miscompiles git

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59363

--- Comment #10 from H.J. Lu <hjl.tools at gmail dot com> ---
valgrind reports:

==13971== Memcheck, a memory error detector
==13971== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==13971== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==13971== Command: ./git-blame Makefile
==13971== 
==13971== Jump to the invalid address stated on the next line
==13971==    at 0x0: ???
==13971==    by 0x50AE88: xdl_emit_hunk_hdr (xutils.c:460)
==13971==    by 0x50B566: xdl_emit_diff (xemit.c:237)
==13971==    by 0x5094DC: xdl_diff (xdiffi.c:601)
==13971==    by 0x5038E4: xdi_diff (xdiff-interface.c:136)
==13971==    by 0x41035E: diff_hunks (blame.c:104)
==13971==    by 0x41296B: cmd_blame (blame.c:815)
==13971==    by 0x405EF4: handle_internal_command (git.c:291)
==13971==    by 0x4056E0: main (git.c:551)
==13971==  Address 0x0 is not stack'd, malloc'd or (recently) free'd
==13971== 
==13971== 
==13971== Process terminating with default action of signal 11 (SIGSEGV)
==13971==  Bad permissions for mapped region at address 0x0
==13971==    at 0x0: ???
==13971==    by 0x50AE88: xdl_emit_hunk_hdr (xutils.c:460)
==13971==    by 0x50B566: xdl_emit_diff (xemit.c:237)
==13971==    by 0x5094DC: xdl_diff (xdiffi.c:601)
==13971==    by 0x5038E4: xdi_diff (xdiff-interface.c:136)
==13971==    by 0x41035E: diff_hunks (blame.c:104)
==13971==    by 0x41296B: cmd_blame (blame.c:815)
==13971==    by 0x405EF4: handle_internal_command (git.c:291)
==13971==    by 0x4056E0: main (git.c:551)
==13971== 
==13971== HEAP SUMMARY:
==13971==     in use at exit: 4,584,430 bytes in 4,375 blocks
==13971==   total heap usage: 7,936 allocs, 3,561 frees, 36,653,925 bytes
allocated
==13971== 
==13971== LEAK SUMMARY:
==13971==    definitely lost: 162 bytes in 8 blocks
==13971==    indirectly lost: 0 bytes in 0 blocks
==13971==      possibly lost: 3,016 bytes in 2 blocks
==13971==    still reachable: 4,581,252 bytes in 4,365 blocks
==13971==         suppressed: 0 bytes in 0 blocks
==13971== Rerun with --leak-check=full to see details of leaked memory
==13971== 
==13971== For counts of detected and suppressed errors, rerun with: -v
==13971== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 2 from 2)
[1]    13971 segmentation fault  valgrind ./git-blame Makefile >| /tmp/1