support setting fpu precision on m68k (closes #20904)
Patch from Andreas Schwab.
diff --git a/Include/pyport.h b/Include/pyport.h
index c706213..69deb9f 100644
--- a/Include/pyport.h
+++ b/Include/pyport.h
@@ -588,6 +588,25 @@
} while (0)
#endif
+#ifdef HAVE_GCC_ASM_FOR_MC68881
+#define HAVE_PY_SET_53BIT_PRECISION 1
+#define _Py_SET_53BIT_PRECISION_HEADER \
+ unsigned int old_fpcr, new_fpcr
+#define _Py_SET_53BIT_PRECISION_START \
+ do { \
+ __asm__ ("fmove.l %%fpcr,%0" : "=g" (old_fpcr)); \
+ /* Set double precision / round to nearest. */ \
+ new_fpcr = (old_fpcr & ~0xf0) | 0x80; \
+ if (new_fpcr != old_fpcr) \
+ __asm__ volatile ("fmove.l %0,%%fpcr" : : "g" (new_fpcr)); \
+ } while (0)
+#define _Py_SET_53BIT_PRECISION_END \
+ do { \
+ if (new_fpcr != old_fpcr) \
+ __asm__ volatile ("fmove.l %0,%%fpcr" : : "g" (old_fpcr)); \
+ } while (0)
+#endif
+
/* default definitions are empty */
#ifndef HAVE_PY_SET_53BIT_PRECISION
#define _Py_SET_53BIT_PRECISION_HEADER
diff --git a/Misc/NEWS b/Misc/NEWS
index 4bef299..5c6a5be 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,8 @@
Core and Builtins
-----------------
+- Issue #20904: Support setting FPU precision on m68k.
+
- Issue #21209: Fix sending tuples to custom generator objects with the yield
from syntax.
diff --git a/configure b/configure
index 7b0c6a9..31a3c67 100755
--- a/configure
+++ b/configure
@@ -13244,6 +13244,38 @@
fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether we can use gcc inline assembler to get and set mc68881 fpcr" >&5
+$as_echo_n "checking whether we can use gcc inline assembler to get and set mc68881 fpcr... " >&6; }
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+int
+main ()
+{
+
+ unsigned int fpcr;
+ __asm__ __volatile__ ("fmove.l %%fpcr,%0" : "=g" (fpcr));
+ __asm__ __volatile__ ("fmove.l %0,%%fpcr" : : "g" (fpcr));
+
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+ have_gcc_asm_for_mc68881=yes
+else
+ have_gcc_asm_for_mc68881=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_gcc_asm_for_mc68881" >&5
+$as_echo "$have_gcc_asm_for_mc68881" >&6; }
+if test "$have_gcc_asm_for_mc68881" = yes
+then
+
+$as_echo "#define HAVE_GCC_ASM_FOR_MC68881 1" >>confdefs.h
+
+fi
+
# Detect whether system arithmetic is subject to x87-style double
# rounding issues. The result of this test has little meaning on non
# IEEE 754 platforms. On IEEE 754, test should return 1 if rounding
diff --git a/configure.ac b/configure.ac
index 457819b..f2e4b1c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3810,6 +3810,19 @@
[Define if we can use gcc inline assembler to get and set x87 control word])
fi
+AC_MSG_CHECKING(whether we can use gcc inline assembler to get and set mc68881 fpcr)
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[
+ unsigned int fpcr;
+ __asm__ __volatile__ ("fmove.l %%fpcr,%0" : "=g" (fpcr));
+ __asm__ __volatile__ ("fmove.l %0,%%fpcr" : : "g" (fpcr));
+]])],[have_gcc_asm_for_mc68881=yes],[have_gcc_asm_for_mc68881=no])
+AC_MSG_RESULT($have_gcc_asm_for_mc68881)
+if test "$have_gcc_asm_for_mc68881" = yes
+then
+ AC_DEFINE(HAVE_GCC_ASM_FOR_MC68881, 1,
+ [Define if we can use gcc inline assembler to get and set mc68881 fpcr])
+fi
+
# Detect whether system arithmetic is subject to x87-style double
# rounding issues. The result of this test has little meaning on non
# IEEE 754 platforms. On IEEE 754, test should return 1 if rounding
diff --git a/pyconfig.h.in b/pyconfig.h.in
index 3574f67..e469f6a 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -313,6 +313,9 @@
/* Define to 1 if you have the `gamma' function. */
#undef HAVE_GAMMA
+/* Define if we can use gcc inline assembler to get and set mc68881 fpcr */
+#undef HAVE_GCC_ASM_FOR_MC68881
+
/* Define if we can use x64 gcc inline assembler */
#undef HAVE_GCC_ASM_FOR_X64