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authorJoseph Myers <joseph@codesourcery.com>2014-10-09 01:07:10 +0000
committerJoseph Myers <joseph@codesourcery.com>2014-10-09 01:07:10 +0000
commit0022e688d082761a1e15b19121303cafbdad33ec (patch)
treefeb146a250a010d44ebcabca982503ca095a28f8
parent73e28d9c885fdfed91e6d70c4aab7e8e801818e3 (diff)
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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--ChangeLog3
-rw-r--r--soft-fp/op-common.h9
2 files changed, 10 insertions, 2 deletions
diff --git a/ChangeLog b/ChangeLog
index f95e3ed79ab..18d1cbcfb6f 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 e62558e4b4a..e0a108a6ee3 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. */ \