The SSE2 detection and enabling could potentially cause
problems for binary distributions of Python in situations where the build machine has SSE2 but the target machine does not. Therefore, don't enable SSE2 instructions automatically on x86.
This commit is contained in:
Mark Dickinson
parent
153c70f6d7
commit
7abf8d4066
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@ -469,7 +469,7 @@ extern "C" {
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the FPU is using 53-bit precision. Here are macros that force this. See
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Python/pystrtod.c for an example of their use. */
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#ifdef USING_X87_FPU
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#ifdef HAVE_GCC_ASM_FOR_X87
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#define _Py_SET_53BIT_PRECISION_HEADER \
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unsigned short old_387controlword, new_387controlword
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#define _Py_SET_53BIT_PRECISION_START \
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@ -31,13 +31,6 @@ Core and Builtins
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value: str(1e11 + 0.5). (This minor issue has existed in 2.x for a
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long time.)
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- On x86, SSE2 instructions for floating-point are automatically
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detected and, where possible, enabled on platforms using the gcc
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compiler. As a consequence, some arithmetic operations may have
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different (more accurate!) results on some platforms, and
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cross-platform consistency of Python arithmetic should be improved.
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This applies particularly to Linux/x86.
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- Issue #1580: On most platforms, use a 'short' float repr: for a
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finite float x, repr(x) now outputs a string based on the shortest
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sequence of decimal digits that rounds to x. Previous behaviour was
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@ -15,6 +15,11 @@
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#define MAX(x, y) ((x) < (y) ? (y) : (x))
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#define MIN(x, y) ((x) < (y) ? (x) : (y))
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/* ascii character tests (as opposed to locale tests) */
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#define ISSPACE(c) ((c) == ' ' || (c) == '\f' || (c) == '\n' || \
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(c) == '\r' || (c) == '\t' || (c) == '\v')
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#define ISDIGIT(c) ((c) >= '0' && (c) <= '9')
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#ifdef HAVE_IEEEFP_H
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#include <ieeefp.h>
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#endif
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@ -188,7 +193,7 @@ PyFloat_FromString(PyObject *v)
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}
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last = s + len;
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while (*s && isspace(Py_CHARMASK(*s)))
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while (*s && ISSPACE(Py_CHARMASK(*s)))
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s++;
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if (*s == '\0') {
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PyErr_SetString(PyExc_ValueError, "empty string for float()");
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@ -245,7 +250,7 @@ PyFloat_FromString(PyObject *v)
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}
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/* Since end != s, the platform made *some* kind of sense out
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of the input. Trust it. */
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while (*end && isspace(Py_CHARMASK(*end)))
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while (*end && ISSPACE(Py_CHARMASK(*end)))
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end++;
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if (*end != '\0') {
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PyOS_snprintf(buffer, sizeof(buffer),
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@ -1275,7 +1280,7 @@ float_fromhex(PyObject *cls, PyObject *arg)
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********************/
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/* leading whitespace and optional sign */
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while (isspace(Py_CHARMASK(*s)))
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while (ISSPACE(Py_CHARMASK(*s)))
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s++;
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if (*s == '-') {
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s++;
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@ -1299,6 +1304,7 @@ float_fromhex(PyObject *cls, PyObject *arg)
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s_store = s;
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if (*s == '0') {
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s++;
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if (*s == 'x' || *s == 'X')
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if (tolower(*s) == (int)'x')
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s++;
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else
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@ -1345,7 +1351,7 @@ float_fromhex(PyObject *cls, PyObject *arg)
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exp = 0;
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/* optional trailing whitespace leading to the end of the string */
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while (isspace(Py_CHARMASK(*s)))
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while (ISSPACE(Py_CHARMASK(*s)))
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s++;
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if (s != s_end)
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goto parse_error;
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@ -13,8 +13,7 @@ double _Py_force_double(double x)
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}
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#endif
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#ifdef USING_X87_FPU
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# ifdef HAVE_GCC_ASM_FOR_X87
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#ifdef HAVE_GCC_ASM_FOR_X87
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/* inline assembly for getting and setting the 387 FPU control word on
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gcc/x86 */
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@ -29,9 +28,6 @@ void _Py_set_387controlword(unsigned short cw) {
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__asm__ __volatile__ ("fldcw %0" : : "m" (cw));
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}
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# else
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# error "Unable to get and set x87 control word"
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# endif
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#endif
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@ -1,5 +1,5 @@
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#! /bin/sh
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# From configure.in Revision: 71663 .
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# From configure.in Revision: 71704 .
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# Guess values for system-dependent variables and create Makefiles.
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# Generated by GNU Autoconf 2.61 for python 3.1.
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#
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@ -21827,174 +21827,21 @@ _ACEOF
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fi
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# David Gay's code in Python/dtoa.c requires that the FPU uses 53-bit
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# The short float repr introduced in Python 3.1 requires the
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# correctly-rounded string <-> double conversion functions in
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# Python/dtoa.c, which in turn require that the FPU uses 53-bit
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# rounding; this is a particular problem on x86, where the x87 FPU has
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# a default rounding precision of 64 bits. For gcc/x86, we try to fix
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# this by:
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#
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# (1) using the SSE2 instruction set when available (it usually is
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# on modern machines)
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# (2) using inline assembler to get and set the x87 FPU control word
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# otherwise.
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#
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# On AMD64 (aka x86-64), gcc automatically enables use of SSE2
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# instructions, so we don't bother trying to detect.
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# this by using inline assembler to get and set the x87 FPU control
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# word.
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if test "$GCC" = yes && test -n "`$CC -dM -E - </dev/null | grep i386`"
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then
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# determine whether we're already using the SSE2 instruction set for math
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# (e.g., this is true by default on OS X/x86)
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{ echo "$as_me:$LINENO: checking whether SSE2 instructions are already enabled for math" >&5
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echo $ECHO_N "checking whether SSE2 instructions are already enabled for math... $ECHO_C" >&6; }
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if test -n "`$CC -dM -E - </dev/null | grep __SSE2_MATH__`"
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then
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ac_sse2_enabled=yes
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else
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ac_sse2_enabled=no
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fi
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{ echo "$as_me:$LINENO: result: $ac_sse2_enabled" >&5
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echo "${ECHO_T}$ac_sse2_enabled" >&6; }
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# if we're not using SSE2 already, we need to either enable it
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# (when available), or use inline assembler to get and set the
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# 387 control word.
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if test $ac_sse2_enabled = no
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then
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# Check cpuid for SSE2 availability. Bits 25 and 26 of edx tell
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# us about SSE and SSE2 respectively.
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{ echo "$as_me:$LINENO: checking whether SSE2 instructions are available on this CPU" >&5
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echo $ECHO_N "checking whether SSE2 instructions are available on this CPU... $ECHO_C" >&6; }
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if test "$cross_compiling" = yes; then
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ac_cv_cpu_has_sse2=no
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else
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cat >conftest.$ac_ext <<_ACEOF
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/* confdefs.h. */
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_ACEOF
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cat confdefs.h >>conftest.$ac_ext
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cat >>conftest.$ac_ext <<_ACEOF
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/* end confdefs.h. */
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int main() {
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unsigned int ax, bx, cx, dx, func;
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func = 1U;
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__asm__ __volatile__ (
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"pushl %%ebx\n\t" /* don't clobber ebx */
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"cpuid\n\t"
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"movl %%ebx, %1\n\t"
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"popl %%ebx"
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: "=a" (ax), "=r" (bx), "=c" (cx), "=d" (dx)
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: "a" (func)
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: "cc" );
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if ((dx & (1U << 25)) && (dx & (1U << 26)))
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return 0;
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else
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return 1;
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}
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_ACEOF
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rm -f conftest$ac_exeext
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if { (ac_try="$ac_link"
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case "(($ac_try" in
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*\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
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*) ac_try_echo=$ac_try;;
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esac
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eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
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(eval "$ac_link") 2>&5
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ac_status=$?
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echo "$as_me:$LINENO: \$? = $ac_status" >&5
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(exit $ac_status); } && { ac_try='./conftest$ac_exeext'
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{ (case "(($ac_try" in
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*\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
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*) ac_try_echo=$ac_try;;
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esac
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eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
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(eval "$ac_try") 2>&5
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ac_status=$?
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echo "$as_me:$LINENO: \$? = $ac_status" >&5
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(exit $ac_status); }; }; then
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ac_cv_cpu_has_sse2=yes
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else
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echo "$as_me: program exited with status $ac_status" >&5
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echo "$as_me: failed program was:" >&5
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sed 's/^/| /' conftest.$ac_ext >&5
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( exit $ac_status )
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ac_cv_cpu_has_sse2=no
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fi
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rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext conftest.$ac_objext conftest.$ac_ext
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fi
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{ echo "$as_me:$LINENO: result: $ac_cv_cpu_has_sse2" >&5
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echo "${ECHO_T}$ac_cv_cpu_has_sse2" >&6; }
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# determine whether gcc accepts options to turn on SSE2
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{ echo "$as_me:$LINENO: checking whether $CC accepts -msse2 -mfpmath=sse" >&5
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echo $ECHO_N "checking whether $CC accepts -msse2 -mfpmath=sse... $ECHO_C" >&6; }
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ac_save_cc="$CC"
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CC="$CC -msse2 -mfpmath=sse"
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if test "$cross_compiling" = yes; then
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ac_cv_msse2_ok=no
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else
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cat >conftest.$ac_ext <<_ACEOF
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/* confdefs.h. */
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_ACEOF
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cat confdefs.h >>conftest.$ac_ext
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cat >>conftest.$ac_ext <<_ACEOF
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/* end confdefs.h. */
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int main() { return 0; }
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_ACEOF
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rm -f conftest$ac_exeext
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if { (ac_try="$ac_link"
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case "(($ac_try" in
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*\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
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*) ac_try_echo=$ac_try;;
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esac
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eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
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(eval "$ac_link") 2>&5
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ac_status=$?
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echo "$as_me:$LINENO: \$? = $ac_status" >&5
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(exit $ac_status); } && { ac_try='./conftest$ac_exeext'
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{ (case "(($ac_try" in
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*\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
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*) ac_try_echo=$ac_try;;
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esac
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eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
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(eval "$ac_try") 2>&5
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ac_status=$?
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echo "$as_me:$LINENO: \$? = $ac_status" >&5
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(exit $ac_status); }; }; then
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ac_cv_msse2_ok=yes
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else
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echo "$as_me: program exited with status $ac_status" >&5
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echo "$as_me: failed program was:" >&5
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sed 's/^/| /' conftest.$ac_ext >&5
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( exit $ac_status )
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ac_cv_msse2_ok=no
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fi
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rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext conftest.$ac_objext conftest.$ac_ext
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fi
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CC="$ac_save_cc"
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{ echo "$as_me:$LINENO: result: $ac_cv_msse2_ok" >&5
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echo "${ECHO_T}$ac_cv_msse2_ok" >&6; }
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if test $ac_cv_cpu_has_sse2 = yes && test $ac_cv_msse2_ok = yes
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then
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BASECFLAGS="$BASECFLAGS -msse2 -mfpmath=sse"
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else
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# SSE2 doesn't appear to be available. Check that it's okay
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# to use gcc inline assembler to get and set x87 control word
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cat >>confdefs.h <<\_ACEOF
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#define USING_X87_FPU 1
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_ACEOF
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{ echo "$as_me:$LINENO: checking whether we can use gcc inline assembler to get and set x87 control word" >&5
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# Check that it's okay to use gcc inline assembler to get and set
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# x87 control word
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{ echo "$as_me:$LINENO: checking whether we can use gcc inline assembler to get and set x87 control word" >&5
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echo $ECHO_N "checking whether we can use gcc inline assembler to get and set x87 control word... $ECHO_C" >&6; }
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cat >conftest.$ac_ext <<_ACEOF
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cat >conftest.$ac_ext <<_ACEOF
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/* confdefs.h. */
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_ACEOF
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cat confdefs.h >>conftest.$ac_ext
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@ -22005,9 +21852,9 @@ int
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main ()
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{
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unsigned short cw;
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__asm__ __volatile__ ("fnstcw %0" : "=m" (cw));
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__asm__ __volatile__ ("fldcw %0" : : "m" (cw));
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unsigned short cw;
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__asm__ __volatile__ ("fnstcw %0" : "=m" (cw));
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__asm__ __volatile__ ("fldcw %0" : : "m" (cw));
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;
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return 0;
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@ -22039,17 +21886,15 @@ sed 's/^/| /' conftest.$ac_ext >&5
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fi
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rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
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{ echo "$as_me:$LINENO: result: $have_gcc_asm_for_x87" >&5
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{ echo "$as_me:$LINENO: result: $have_gcc_asm_for_x87" >&5
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echo "${ECHO_T}$have_gcc_asm_for_x87" >&6; }
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if test "$have_gcc_asm_for_x87" = yes
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then
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if test "$have_gcc_asm_for_x87" = yes
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then
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cat >>confdefs.h <<\_ACEOF
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#define HAVE_GCC_ASM_FOR_X87 1
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_ACEOF
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|
||||
fi
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fi
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fi
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fi
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|
|
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107
configure.in
107
configure.in
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|
@ -3142,97 +3142,28 @@ then
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in ARM mixed-endian order (byte order 45670123)])
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fi
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# David Gay's code in Python/dtoa.c requires that the FPU uses 53-bit
|
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# rounding; this is a particular problem on x86, where the x87 FPU has
|
||||
# a default rounding precision of 64 bits. For gcc/x86, we try to fix
|
||||
# this by:
|
||||
#
|
||||
# (1) using the SSE2 instruction set when available (it usually is
|
||||
# on modern machines)
|
||||
# (2) using inline assembler to get and set the x87 FPU control word
|
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# otherwise.
|
||||
#
|
||||
# On AMD64 (aka x86-64), gcc automatically enables use of SSE2
|
||||
# instructions, so we don't bother trying to detect.
|
||||
|
||||
# The short float repr introduced in Python 3.1 requires the
|
||||
# correctly-rounded string <-> double conversion functions from
|
||||
# Python/dtoa.c, which in turn require that the FPU uses 53-bit
|
||||
# rounding; this is a problem on x86, where the x87 FPU has a default
|
||||
# rounding precision of 64 bits. For gcc/x86, we try to fix this by
|
||||
# using inline assembler to get and set the x87 FPU control word.
|
||||
if test "$GCC" = yes && test -n "`$CC -dM -E - </dev/null | grep i386`"
|
||||
then
|
||||
# determine whether we're already using the SSE2 instruction set for math
|
||||
# (e.g., this is true by default on OS X/x86)
|
||||
AC_MSG_CHECKING(whether SSE2 instructions are already enabled for math)
|
||||
if test -n "`$CC -dM -E - </dev/null | grep __SSE2_MATH__`"
|
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# Check that it's okay to use gcc inline assembler to get and set
|
||||
# x87 control word. It should be, but you never know...
|
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AC_MSG_CHECKING(whether we can use gcc inline assembler to get and set x87 control word)
|
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AC_TRY_COMPILE([], [
|
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unsigned short cw;
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__asm__ __volatile__ ("fnstcw %0" : "=m" (cw));
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__asm__ __volatile__ ("fldcw %0" : : "m" (cw));
|
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],
|
||||
[have_gcc_asm_for_x87=yes], [have_gcc_asm_for_x87=no])
|
||||
AC_MSG_RESULT($have_gcc_asm_for_x87)
|
||||
if test "$have_gcc_asm_for_x87" = yes
|
||||
then
|
||||
ac_sse2_enabled=yes
|
||||
else
|
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ac_sse2_enabled=no
|
||||
fi
|
||||
AC_MSG_RESULT($ac_sse2_enabled)
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|
||||
# if we're not using SSE2 already, we need to either enable it
|
||||
# (when available), or use inline assembler to get and set the
|
||||
# 387 control word.
|
||||
if test $ac_sse2_enabled = no
|
||||
then
|
||||
# Check cpuid for SSE2 availability. Bits 25 and 26 of edx tell
|
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# us about SSE and SSE2 respectively.
|
||||
AC_MSG_CHECKING(whether SSE2 instructions are available on this CPU)
|
||||
AC_TRY_RUN([
|
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int main() {
|
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unsigned int ax, bx, cx, dx, func;
|
||||
func = 1U;
|
||||
__asm__ __volatile__ (
|
||||
"pushl %%ebx\n\t" /* don't clobber ebx */
|
||||
"cpuid\n\t"
|
||||
"movl %%ebx, %1\n\t"
|
||||
"popl %%ebx"
|
||||
: "=a" (ax), "=r" (bx), "=c" (cx), "=d" (dx)
|
||||
: "a" (func)
|
||||
: "cc" );
|
||||
if ((dx & (1U << 25)) && (dx & (1U << 26)))
|
||||
return 0;
|
||||
else
|
||||
return 1;
|
||||
}
|
||||
],
|
||||
ac_cv_cpu_has_sse2=yes,
|
||||
ac_cv_cpu_has_sse2=no,
|
||||
ac_cv_cpu_has_sse2=no)
|
||||
AC_MSG_RESULT($ac_cv_cpu_has_sse2)
|
||||
|
||||
# determine whether gcc accepts options to turn on SSE2
|
||||
AC_MSG_CHECKING(whether $CC accepts -msse2 -mfpmath=sse)
|
||||
ac_save_cc="$CC"
|
||||
CC="$CC -msse2 -mfpmath=sse"
|
||||
AC_TRY_RUN([int main() { return 0; }],
|
||||
ac_cv_msse2_ok=yes,
|
||||
ac_cv_msse2_ok=no,
|
||||
ac_cv_msse2_ok=no)
|
||||
CC="$ac_save_cc"
|
||||
AC_MSG_RESULT($ac_cv_msse2_ok)
|
||||
|
||||
if test $ac_cv_cpu_has_sse2 = yes && test $ac_cv_msse2_ok = yes
|
||||
then
|
||||
BASECFLAGS="$BASECFLAGS -msse2 -mfpmath=sse"
|
||||
else
|
||||
# SSE2 doesn't appear to be available. Check that it's okay
|
||||
# to use gcc inline assembler to get and set x87 control word
|
||||
AC_DEFINE(USING_X87_FPU, 1,
|
||||
[Define on x86 hardware if the x87 FPU is being used
|
||||
for floating-point arithmetic])
|
||||
AC_MSG_CHECKING(whether we can use gcc inline assembler to get and set x87 control word)
|
||||
AC_TRY_COMPILE([], [
|
||||
unsigned short cw;
|
||||
__asm__ __volatile__ ("fnstcw %0" : "=m" (cw));
|
||||
__asm__ __volatile__ ("fldcw %0" : : "m" (cw));
|
||||
],
|
||||
[have_gcc_asm_for_x87=yes], [have_gcc_asm_for_x87=no])
|
||||
AC_MSG_RESULT($have_gcc_asm_for_x87)
|
||||
if test "$have_gcc_asm_for_x87" = yes
|
||||
then
|
||||
AC_DEFINE(HAVE_GCC_ASM_FOR_X87, 1,
|
||||
[Define if we can use gcc inline assembler to get and set x87 control word])
|
||||
fi
|
||||
fi
|
||||
AC_DEFINE(HAVE_GCC_ASM_FOR_X87, 1,
|
||||
[Define if we can use gcc inline assembler to get and set x87 control word])
|
||||
fi
|
||||
fi
|
||||
|
||||
|
|
|
|||
|
|
@ -989,10 +989,6 @@
|
|||
/* Define if you want to use computed gotos in ceval.c. */
|
||||
#undef USE_COMPUTED_GOTOS
|
||||
|
||||
/* Define on x86 hardware if the x87 FPU is being used for floating-point
|
||||
arithmetic */
|
||||
#undef USING_X87_FPU
|
||||
|
||||
/* Define if a va_list is an array of some kind */
|
||||
#undef VA_LIST_IS_ARRAY
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue