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| author | Joseph Myers <joseph@codesourcery.com> | 2014-10-09 01:07:10 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2014-10-09 01:07:10 +0000 |
| commit | 0022e688d082761a1e15b19121303cafbdad33ec (patch) | |
| tree | feb146a250a010d44ebcabca982503ca095a28f8 | |
| parent | 73e28d9c885fdfed91e6d70c4aab7e8e801818e3 (diff) | |
| download | glibc-0022e688d082761a1e15b19121303cafbdad33ec.tar.gz glibc-0022e688d082761a1e15b19121303cafbdad33ec.tar.xz glibc-0022e688d082761a1e15b19121303cafbdad33ec.zip | |
soft-fp: Fix _FP_TO_INT latent bug in overflow handling.
This patch fixes a latent bug in _FP_TO_INT regarding handling of arguments with maximum exponent (infinities and NaNs). If the maximum exponent is below that calculated as an overflow threshold, such values would incorrectly be treated as normal values for the purposes of the conversion. This could not occur for any of the conversions actually occurring in glibc, libgcc or the Linux kernel (the maximum exponent for float is, just, big enough to ensure overflow for unsigned __int128), but would apply if soft-fp were used for IEEE binary16. Appropriate checks are inserted to ensure that the maximum exponent is always treated as an overflowing exponent, and never as a normal one. Tested for powerpc-nofpu that the disassembly of installed shared libraries is unchanged by this patch. * soft-fp/op-common.h (_FP_TO_INT): Ensure maximum exponent is treated as invalid conversion, not as normal exponent.
| -rw-r--r-- | ChangeLog | 3 | ||||
| -rw-r--r-- | soft-fp/op-common.h | 9 |
2 files changed, 10 insertions, 2 deletions
diff --git a/ChangeLog b/ChangeLog index f95e3ed79a..18d1cbcfb6 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,8 @@ 2014-10-09 Joseph Myers <joseph@codesourcery.com> + * soft-fp/op-common.h (_FP_TO_INT): Ensure maximum exponent is + treated as invalid conversion, not as normal exponent. + * soft-fp/op-common.h (_FP_CMP_CHECK_NAN): New macro. (_FP_CMP): Add extra argument EX. Call _FP_CMP_CHECK_NAN. (_FP_CMP_EQ): Likewise. diff --git a/soft-fp/op-common.h b/soft-fp/op-common.h index e62558e4b4..e0a108a6ee 100644 --- a/soft-fp/op-common.h +++ b/soft-fp/op-common.h @@ -1368,7 +1368,9 @@ else \ FP_SET_EXCEPTION (FP_EX_INEXACT); \ } \ - else if (X##_e >= _FP_EXPBIAS_##fs + rsize - (rsigned > 0 || X##_s) \ + else if (X##_e >= (_FP_EXPMAX_##fs < _FP_EXPBIAS_##fs + rsize \ + ? _FP_EXPMAX_##fs \ + : _FP_EXPBIAS_##fs + rsize - (rsigned > 0 || X##_s)) \ || (!rsigned && X##_s)) \ { \ /* Overflow or converting to the most negative integer. */ \ @@ -1385,7 +1387,10 @@ r = ~r; \ } \ \ - if (rsigned && X##_s && X##_e == _FP_EXPBIAS_##fs + rsize - 1) \ + if (_FP_EXPBIAS_##fs + rsize - 1 < _FP_EXPMAX_##fs \ + && rsigned \ + && X##_s \ + && X##_e == _FP_EXPBIAS_##fs + rsize - 1) \ { \ /* Possibly converting to most negative integer; check the \ mantissa. */ \ |