From 0022e688d082761a1e15b19121303cafbdad33ec Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Thu, 9 Oct 2014 01:07:10 +0000 Subject: 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. --- soft-fp/op-common.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'soft-fp') diff --git a/soft-fp/op-common.h b/soft-fp/op-common.h index e62558e..e0a108a 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. */ \ -- cgit v1.1