| Message ID | g4ipqxukrj.fsf@linaro.org |
|---|---|
| State | New |
| Headers | show |
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 07/20/11 07:47, Richard Sandiford wrote: > This patch makes regcprop check HARD_REGNO_MODE_OK before creating a > hard register in a different mode. It fixes a segfault in a build of > bionic on ARM. > > The missing check usually doesn't cause problems. The define_insn > constraints are likely to reject invalid registers for "real" insns, > while debug insns are often able to get away with them without triggering > an ICE. It only showed up on ARM because a debug insn used (reg:SI d16), > and arm_dwarf_register_span returned a zero-length parallel for this > (invalid) case. The host compiler also happened not to optimise away > the dead size assignment described here: > > http://gcc.gnu.org/ml/gcc/2011-07/msg00376.html > > so we would seg trying to access beyond the end of the vector. > > Tested on x86_64-linux-gnu and arm-linux-gnueabi. OK to install? > > Richard > > > gcc/ > * regcprop.c (maybe_mode_change): Check HARD_REGNO_MODE_OK. OK. Jeff -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJOJuFqAAoJEBRtltQi2kC7LnkH+wbkbNYXRN+1ew8lh49m80HO SAx2lC3eyMXuR581lwG4vT7HBx9rLfJ/5s+smeAr8Vo80+raN2PkST/f2Vj5WKDg O0NSqha/Zw4QLSDJ7XApg2Fi/MHZ+z71kFXXb8Ko9KPHMMhVlwxbnE7Jn3QcRpAQ s9BgNtT0RHzS3zdnmjnbSEFGKDj9K3DNuw0Vp0+mJV6pGh+ljI7uFUJh4QI3pywj uqzQVsKXVtsb7lx7rXlVdCuvf+4fYMSdOPq92BBes4s0CtgyN0HEy6ihpd4qj2aq GLbvM9sTIyOicpzWNs8cBCXWPMRKvR7si5gr7jZms2Oa3si3JMyqV58HAn+Z3Tk= =JXtm -----END PGP SIGNATURE-----
Index: gcc/regcprop.c =================================================================== --- gcc/regcprop.c 2011-06-22 16:46:35.000000000 +0100 +++ gcc/regcprop.c 2011-07-20 13:04:37.000000000 +0100 @@ -418,10 +418,9 @@ maybe_mode_change (enum machine_mode ori offset = ((WORDS_BIG_ENDIAN ? wordoffset : 0) + (BYTES_BIG_ENDIAN ? byteoffset : 0)); - return gen_rtx_raw_REG (new_mode, - regno + subreg_regno_offset (regno, orig_mode, - offset, - new_mode)); + regno += subreg_regno_offset (regno, orig_mode, offset, new_mode); + if (HARD_REGNO_MODE_OK (regno, new_mode)) + return gen_rtx_raw_REG (new_mode, regno); } return NULL_RTX; }
This patch makes regcprop check HARD_REGNO_MODE_OK before creating a hard register in a different mode. It fixes a segfault in a build of bionic on ARM. The missing check usually doesn't cause problems. The define_insn constraints are likely to reject invalid registers for "real" insns, while debug insns are often able to get away with them without triggering an ICE. It only showed up on ARM because a debug insn used (reg:SI d16), and arm_dwarf_register_span returned a zero-length parallel for this (invalid) case. The host compiler also happened not to optimise away the dead size assignment described here: http://gcc.gnu.org/ml/gcc/2011-07/msg00376.html so we would seg trying to access beyond the end of the vector. Tested on x86_64-linux-gnu and arm-linux-gnueabi. OK to install? Richard gcc/ * regcprop.c (maybe_mode_change): Check HARD_REGNO_MODE_OK.