Fix x86_64 -mfpmath=387 float_t, double_t (bug 20787) [committed]

[Joseph Myers <joseph at codesourcery dot com>]

Bug 20787 reports that, while float_t and double_t for 32-bit x86
properly respect -mfpmath=sse, for x86_64 they fail to reflect
-mfpmath=387, which is valid if unusual and results in FLT_EVAL_METHOD
being 2.  This patch fixes the definitions to respect
__FLT_EVAL_METHOD__ in that case, arranging for the test that the
types correspond with FLT_EVAL_METHOD to be run with both -mfpmath=387
and -mfpmath=sse.

Note: this patch will also have the effect of making float_t and
double_t be long double for x86_64 with -mfpmath=sse+387, when
FLT_EVAL_METHOD is -1.  It seems reasonable for x86_64 to be
consistent with 32-bit x86 in this case (and that definition is
conservatively safe, in that it makes the types correspond to the
widest evaluation format that might be used).

Tested for x86-64 and x86.  Committed.

2016-11-23  Joseph Myers  <joseph@codesourcery.com>

	[BZ #20787]
	* sysdeps/x86/bits/mathdef.h (float_t): Do not define to float if
	[__x86_64__] when __FLT_EVAL_METHOD__ is nonzero.
	(double_t): Do not define to double if [__x86_64__] when
	__FLT_EVAL_METHOD__ is nonzero.
	* sysdeps/x86/fpu/test-flt-eval-method-387.c: New file.
	* sysdeps/x86/fpu/test-flt-eval-method-sse.c: Likewise.
	* sysdeps/x86/fpu/Makefile [$(subdir) = math] (tests): Add
	test-flt-eval-method-387 and test-flt-eval-method-sse.
	[$(subdir) = math] (CFLAGS-test-flt-eval-method-387.c): New
	variable.
	[$(subdir) = math] (CFLAGS-test-flt-eval-method-sse.c): Likewise.

diff --git a/sysdeps/x86/bits/mathdef.h b/sysdeps/x86/bits/mathdef.h
index e61c28a..9423a7f 100644
--- a/sysdeps/x86/bits/mathdef.h
+++ b/sysdeps/x86/bits/mathdef.h
@@ -22,7 +22,8 @@
 #if defined __USE_ISOC99 && defined _MATH_H && !defined _MATH_H_MATHDEF
 # define _MATH_H_MATHDEF	1
 
-# if defined __x86_64__ || (defined __FLT_EVAL_METHOD__ && __FLT_EVAL_METHOD__ == 0)
+# if ((defined __x86_64__ && !defined __FLT_EVAL_METHOD__)		\
+      || (defined __FLT_EVAL_METHOD__ && __FLT_EVAL_METHOD__ == 0))
 /* The x86-64 architecture computes values with the precission of the
    used type.  Similarly for -m32 -mfpmath=sse.  */
 typedef float float_t;		/* `float' expressions are evaluated as `float'.  */
diff --git a/sysdeps/x86/fpu/Makefile b/sysdeps/x86/fpu/Makefile
index b561995..a8047a4 100644
--- a/sysdeps/x86/fpu/Makefile
+++ b/sysdeps/x86/fpu/Makefile
@@ -1,7 +1,11 @@
 ifeq ($(subdir),math)
 libm-support += powl_helper
-tests += test-fenv-sse test-fenv-clear-sse test-fenv-x87 test-fenv-sse-2
+tests += test-fenv-sse test-fenv-clear-sse test-fenv-x87 test-fenv-sse-2 \
+	 test-flt-eval-method-387 test-flt-eval-method-sse
 CFLAGS-test-fenv-sse.c += -msse2 -mfpmath=sse
 CFLAGS-test-fenv-clear-sse.c += -msse2 -mfpmath=sse
 CFLAGS-test-fenv-sse-2.c += -msse2 -mfpmath=sse
+CFLAGS-test-flt-eval-method-387.c += -fexcess-precision=standard -mfpmath=387
+CFLAGS-test-flt-eval-method-sse.c += -fexcess-precision=standard -msse2 \
+				     -mfpmath=sse
 endif
diff --git a/sysdeps/x86/fpu/test-flt-eval-method-387.c b/sysdeps/x86/fpu/test-flt-eval-method-387.c
new file mode 100644
index 0000000..2fb7acf
--- /dev/null
+++ b/sysdeps/x86/fpu/test-flt-eval-method-387.c
@@ -0,0 +1 @@
+#include <test-flt-eval-method.c>
diff --git a/sysdeps/x86/fpu/test-flt-eval-method-sse.c b/sysdeps/x86/fpu/test-flt-eval-method-sse.c
new file mode 100644
index 0000000..2fb7acf
--- /dev/null
+++ b/sysdeps/x86/fpu/test-flt-eval-method-sse.c
@@ -0,0 +1 @@
+#include <test-flt-eval-method.c>

-- 
Joseph S. Myers
joseph@codesourcery.com