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e500 port: fix fpu_control.h constant values
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: <libc-alpha at sourceware dot org>
- Cc: "Ryan S. Arnold" <ryan dot arnold at gmail dot com>
- Date: Thu, 26 Sep 2013 00:29:33 +0000
- Subject: e500 port: fix fpu_control.h constant values
- Authentication-results: sourceware.org; auth=none
e500 port testing shows that the values in the e500 case in
fpu_control.h, which I took originally from the fpu_control.h in
Aldy's SPE add-on, don't actually correspond correctly to bits in
SPEFSCR. I've no idea where the values in the SPE add-on originated,
but this patch corrects various values to match the architecture
documentation.
(Note: the _FPU_DEFAULT value is the one needed for correct operation;
without exceptions enabled at the hardware level, you get such things
as flush-to-zero of denormal operands causing libm functions to go
into infinite loops, so can't run the testsuite. I'll prepare a
kernel patch to make the kernel actually use that as the default
value; in the absence of such a kernel fix, glibc would need support
for disabling the present assumption that the initial control word
setting is _FPU_DEFAULT and __setfpucw doesn't need calling on startup
unless __fpu_control has a different value.)
2013-09-26 Joseph Myers <joseph@codesourcery.com>
* sysdeps/powerpc/fpu_control.h [__NO_FPRS__ && !_SOFT_FLOAT]
(_FPU_MASK_OM): Define as 0x04.
[__NO_FPRS__ && !_SOFT_FLOAT] (_FPU_MASK_UM): Define as 0x08.
[__NO_FPRS__ && !_SOFT_FLOAT] (_FPU_RESERVED): Define as
0x00c10080.
[__NO_FPRS__ && !_SOFT_FLOAT] (_FPU_DEFAULT): Define as
0x0000007c.
[__NO_FPRS__ && !_SOFT_FLOAT] (_FPU_IEEE): Define as _FPU_DEFAULT.
diff --git a/sysdeps/powerpc/fpu_control.h b/sysdeps/powerpc/fpu_control.h
index c61a2e1..1771722 100644
--- a/sysdeps/powerpc/fpu_control.h
+++ b/sysdeps/powerpc/fpu_control.h
@@ -38,20 +38,18 @@ extern fpu_control_t __fpu_control;
/* masking of interrupts */
# define _FPU_MASK_ZM 0x10 /* zero divide */
-# define _FPU_MASK_OM 0x40 /* overflow */
-# define _FPU_MASK_UM 0x80 /* underflow */
+# define _FPU_MASK_OM 0x04 /* overflow */
+# define _FPU_MASK_UM 0x08 /* underflow */
# define _FPU_MASK_XM 0x40 /* inexact */
# define _FPU_MASK_IM 0x20 /* invalid operation */
-# define _FPU_RESERVED 0xff3fff7f /* These bits are reserved and not changed. */
-
-/* The fdlibm code requires no interrupts for exceptions. */
-# define _FPU_DEFAULT 0x00000000 /* Default value. */
+# define _FPU_RESERVED 0x00c10080 /* These bits are reserved and not changed. */
-/* IEEE: same as above, but (some) exceptions;
- we leave the 'inexact' exception off.
- */
-# define _FPU_IEEE 0x000003c0
+/* Correct IEEE semantics require traps to be enabled at the hardware
+ level; the kernel then does the emulation and determines whether
+ generation of signals from those traps was enabled using prctl. */
+# define _FPU_DEFAULT 0x0000007c /* Default value. */
+# define _FPU_IEEE _FPU_DEFAULT
/* Type of the control word. */
typedef unsigned int fpu_control_t;
--
Joseph S. Myers
joseph@codesourcery.com