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authorJoseph Myers <joseph@codesourcery.com>2014-10-09 15:00:37 +0000
committerJoseph Myers <joseph@codesourcery.com>2014-10-09 15:00:37 +0000
commita736ec370a05e4b37e6101eb3168bf8dc4c5af13 (patch)
tree665968c60d407cb06565ee80c8c2dcc996f42807
parentff12c11f4515a9f83467471e8d4381eb3dbc06b5 (diff)
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soft-fp: Support rsigned == 2 in _FP_TO_INT.
Continuing the addition of soft-fp features in the Linux kernel version, this patch adds _FP_TO_INT support for rsigned == 2 (reduce overflowing results modulo 2^rsize to fit in the destination, used for alpha emulation). The kernel version is buggy; it can left shift by a negative amount when right shifting is required in an overflow case (the kernel version also has other bugs fixed long ago in glibc; at least, spurious exceptions converting to the most negative integer). This version avoids that by handling overflow (other than to 0) for rsigned == 2 along with the normal non-overflow case, which already properly determines the direction in which to shift. Tested for powerpc-nofpu. Some functions get slightly bigger and some get slightly smaller, no doubt as a result of the change to where in the macro "inexact" is raised, but I don't think those changes are significant. Also tested for powerpc-nofpu with the relevant __fix* functions changed to use rsigned == 2 (which is after all just as valid as rsigned == 1 in IEEE terms), including verifying the results and exceptions for various cases of conversions. With these seven patches, the one remaining feature to add for the soft-fp code to have all the features of the kernel version is _FP_TO_INT_ROUND. * soft-fp/op-common.h (_FP_TO_INT): Handle rsigned == 2.
-rw-r--r--ChangeLog2
-rw-r--r--soft-fp/op-common.h45
2 files changed, 40 insertions, 7 deletions
diff --git a/ChangeLog b/ChangeLog
index fa354c23349..f8f2221d7c0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,7 @@
2014-10-09 Joseph Myers <joseph@codesourcery.com>
+ * soft-fp/op-common.h (_FP_TO_INT): Handle rsigned == 2.
+
* soft-fp/soft-fp.h (FP_EX_INVALID_SNAN): New macro.
(FP_EX_INVALID_IMZ): Likewise.
(FP_EX_INVALID_IMZ_FMA): Likewise.
diff --git a/soft-fp/op-common.h b/soft-fp/op-common.h
index 8344be5aadd..3591c47efbf 100644
--- a/soft-fp/op-common.h
+++ b/soft-fp/op-common.h
@@ -1399,6 +1399,8 @@
1: the number is required to be -(2^(rsize-1))..(2^(rsize-1))-1, if not,
NV is set plus the result is either -(2^(rsize-1)) or (2^(rsize-1))-1
depending on the sign in such case.
+ 2: the number is required to be -(2^(rsize-1))..(2^(rsize-1))-1, if not,
+ NV is set plus the result is reduced modulo 2^rsize.
-1: the number is required to be -(2^(rsize-1))..(2^rsize)-1, if not, NV is
set plus the result is either -(2^(rsize-1)) or (2^(rsize-1))-1
depending on the sign in such case. */
@@ -1420,10 +1422,28 @@
else \
FP_SET_EXCEPTION (FP_EX_INEXACT); \
} \
- 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)) \
+ else if (rsigned == 2 \
+ && (X##_e \
+ >= ((_FP_EXPMAX_##fs \
+ < _FP_EXPBIAS_##fs + _FP_FRACBITS_##fs + rsize - 1) \
+ ? _FP_EXPMAX_##fs \
+ : _FP_EXPBIAS_##fs + _FP_FRACBITS_##fs + rsize - 1))) \
+ { \
+ /* Overflow resulting in 0. */ \
+ r = 0; \
+ FP_SET_EXCEPTION (FP_EX_INVALID \
+ | FP_EX_INVALID_CVI \
+ | ((FP_EX_INVALID_SNAN \
+ && _FP_ISSIGNAN (fs, wc, X)) \
+ ? FP_EX_INVALID_SNAN \
+ : 0)); \
+ } \
+ else if (rsigned != 2 \
+ && (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. */ \
if (rsigned) \
@@ -1470,6 +1490,7 @@
} \
else \
{ \
+ int _FP_TO_INT_inexact = 0; \
_FP_FRAC_HIGH_RAW_##fs (X) |= _FP_IMPLBIT_##fs; \
if (X##_e >= _FP_EXPBIAS_##fs + _FP_FRACBITS_##fs - 1) \
{ \
@@ -1478,17 +1499,27 @@
} \
else \
{ \
- int _FP_TO_INT_inexact; \
_FP_FRAC_SRST_##wc (X, _FP_TO_INT_inexact, \
(_FP_FRACBITS_##fs + _FP_EXPBIAS_##fs - 1 \
- X##_e), \
_FP_FRACBITS_##fs); \
- if (_FP_TO_INT_inexact) \
- FP_SET_EXCEPTION (FP_EX_INEXACT); \
_FP_FRAC_ASSEMBLE_##wc (r, X, rsize); \
} \
if (rsigned && X##_s) \
r = -r; \
+ if (rsigned == 2 && X##_e >= _FP_EXPBIAS_##fs + rsize - 1) \
+ { \
+ /* Overflow or converting to the most negative integer. */ \
+ if (X##_e > _FP_EXPBIAS_##fs + rsize - 1 \
+ || !X##_s \
+ || r != (((typeof (r)) 1) << (rsize - 1))) \
+ { \
+ _FP_TO_INT_inexact = 0; \
+ FP_SET_EXCEPTION (FP_EX_INVALID | FP_EX_INVALID_CVI); \
+ } \
+ } \
+ if (_FP_TO_INT_inexact) \
+ FP_SET_EXCEPTION (FP_EX_INEXACT); \
} \
} \
while (0)