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| author | Joseph Myers <joseph@codesourcery.com> | 2014-10-09 00:58:42 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2014-10-09 00:58:42 +0000 |
| commit | 2d6a47ba4ca899746db7fb5ba75a82f2cda93a91 (patch) | |
| tree | 0d91e70c7c2d40036e46c351abd1346bcc6d3437 /soft-fp/soft-fp.h | |
| parent | 620f462e88f6e7b59488a963b3c42d89035e4ba6 (diff) | |
| download | glibc-2d6a47ba4ca899746db7fb5ba75a82f2cda93a91.tar.gz | |
soft-fp: Remove FP_CLEAR_EXCEPTIONS.
As noted in
<https://sourceware.org/ml/libc-alpha/2013-10/msg00516.html>, the
soft-fp macro FP_CLEAR_EXCEPTIONS should not be necessary, as soft-fp
code should never set an exception and later clear it.
In fact, all four uses in glibc (for SPARC) are indeed unnecessary:
they appear in files that convert 32-bit or 64-bit integers to IEEE
binary128, an operation that can never raise any exceptions. If this
was intended to enable the compiler to optimize away any FP_FROM_INT
code testing for exceptional cases, we now have a better way of doing
this: defining FP_NO_EXCEPTIONS before including soft-fp.h causes all
code handling exceptions to be stubbed out, and the rounding mode to
be hardwired for round-to-zero, to allow such optimizations for source
files where (a) the operation in question, for the particular types in
question, can never raise exceptions, but (b) some instances of the
operation for other types can, so the macros used in the file do
contain references to rounding or exceptions, albeit dead in that
particular file.
The uses in the Linux kernel are also unnecessary (clearing exceptions
at a point where they are already cleared).
This patch duly removes FP_CLEAR_EXCEPTIONS, making the SPARC code in
question use FP_NO_EXCEPTIONS and stop using exception-related macros.
* soft-fp/soft-fp.h (FP_CLEAR_EXCEPTIONS): Remove macro.
* sysdeps/sparc/sparc32/soft-fp/q_itoq.c: Define FP_NO_EXCEPTIONS.
(_Q_itoq): Do not use FP_DECL_EX, FP_CLEAR_EXCEPTIONS or
FP_HANDLE_EXCEPTIONS.
* sysdeps/sparc/sparc32/soft-fp/q_lltoq.c: Define FP_NO_EXCEPTIONS.
(_Q_lltoq): Do not use FP_DECL_EX, FP_CLEAR_EXCEPTIONS or
FP_HANDLE_EXCEPTIONS.
* sysdeps/sparc/sparc32/soft-fp/q_ulltoq.c: Define FP_NO_EXCEPTIONS.
(_Q_ulltoq): Do not use FP_DECL_EX, FP_CLEAR_EXCEPTIONS or
FP_HANDLE_EXCEPTIONS.
* sysdeps/sparc/sparc32/soft-fp/q_utoq.c: Define FP_NO_EXCEPTIONS.
(_Q_utoq): Do not use FP_DECL_EX, FP_CLEAR_EXCEPTIONS or
FP_HANDLE_EXCEPTIONS.
Diffstat (limited to 'soft-fp/soft-fp.h')
| -rw-r--r-- | soft-fp/soft-fp.h | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/soft-fp/soft-fp.h b/soft-fp/soft-fp.h index 5fb7358cfa..ead9c97874 100644 --- a/soft-fp/soft-fp.h +++ b/soft-fp/soft-fp.h @@ -128,9 +128,6 @@ #define FP_SET_EXCEPTION(ex) \ _fex |= (ex) -#define FP_CLEAR_EXCEPTIONS \ - _fex = 0 - #define FP_CUR_EXCEPTIONS \ (_fex) |