PERFORCE change 34799 for review
Peter Wemm
peter at FreeBSD.org
Mon Jul 21 17:32:30 PDT 2003
http://perforce.freebsd.org/chv.cgi?CH=34799
Change 34799 by peter at peter_hammer on 2003/07/21 17:31:45
initial shot at fleshing out SSE support in the fp*() API
Affected files ...
.. //depot/projects/hammer/sys/amd64/include/ieeefp.h#2 edit
Differences ...
==== //depot/projects/hammer/sys/amd64/include/ieeefp.h#2 (text+ko) ====
@@ -90,6 +90,13 @@
#define FP_RND_FLD 0xc00 /* round control field */
#define FP_STKY_FLD 0x3f /* sticky flags field */
+#define SSE_STKY_FLD 0x3f /* exception flags */
+#define SSE_DAZ_FLD 0x40 /* Denormals are zero */
+#define SSE_MSKS_FLD 0x1f80 /* exception masks field */
+#define SSE_RND_FLD 0x6000 /* rounding control */
+#define SSE_FZ_FLD 0x8000 /* flush to zero on underflow */
+
+
/*
* FP register bit field offsets
*/
@@ -98,84 +105,164 @@
#define FP_RND_OFF 10 /* round control offset */
#define FP_STKY_OFF 0 /* sticky flags offset */
+#define SSE_STKY_OFF 0 /* exception flags offset */
+#define SSE_DAZ_OFF 6 /* DAZ exception mask offset */
+#define SSE_MSKS_OFF 7 /* other exception masks offset */
+#define SSE_RND_OFF 13 /* rounding control offset */
+#define SSE_FZ_OFF 15 /* flush to zero offset */
+
#ifdef __GNUC__
#define __fldenv(addr) __asm __volatile("fldenv %0" : : "m" (*(addr)))
#define __fnstenv(addr) __asm __volatile("fnstenv %0" : "=m" (*(addr)))
+#define __fldcw(addr) __asm __volatile("fldcw %0" : "=m" (*(addr)))
#define __fnstcw(addr) __asm __volatile("fnstcw %0" : "=m" (*(addr)))
#define __fnstsw(addr) __asm __volatile("fnstsw %0" : "=m" (*(addr)))
+#define __ldmxcsr(addr) __asm __volatile("ldmxcsr %0" : "=m" (*(addr)))
+#define __stmxcsr(addr) __asm __volatile("stmxcsr %0" : "=m" (*(addr)))
/*
- * return the contents of a FP register
+ * General notes about conflicting SSE vs FP status bits.
+ * This code assumes that software will not fiddle with the control
+ * bits of the SSE and x87 in such a way to get them out of sync and
+ * still expect this to work. Break this at your peril.
+ * Because I based this on the i386 port, the x87 state is used for
+ * the fpget*() functions, and is shadowed into the SSE state for
+ * the fpset*() functions. For dual source fpget*() functions, I
+ * merge the two together. I think.
+ */
+
+/* Set rounding control */
+static __inline__ fp_rnd_t
+fpgetround(void)
+{
+ unsigned short _cw;
+
+ __fnstcw(&_cw);
+ return ((_cw & FP_RND_FLD) >> FP_RND_OFF);
+}
+
+static __inline__ fp_rnd_t
+fpsetround(fp_rnd_t _m)
+{
+ unsigned short _cw;
+ unsigned int _mxcsr;
+ fp_rnd_t _p;
+
+ __fnstcw(&_cw);
+ _p = (_cw & FP_RND_FLD) >> FP_RND_OFF;
+ _cw &= ~FP_RND_FLD;
+ _cw |= (_m << FP_RND_OFF) & FP_RND_FLD;
+ __fldcw(&_cw);
+ __stmxcsr(&_mxcsr);
+ _mxcsr &= ~SSE_RND_FLD;
+ _mxcsr |= (_m << SSE_RND_OFF) & SSE_RND_FLD;
+ __ldmxcsr(&_mxcsr);
+ return (_p);
+}
+
+/*
+ * Set precision for fadd/fsub/fsqrt etc x87 instructions
+ * There is no equivalent SSE mode or control. It always runs
+ * in 64 bit precision mode for SSE2 calculations.
*/
-static __inline__ int
-__fpgetreg(int _reg)
+static __inline__ fp_prec_t
+fpgetprec(void)
+{
+ unsigned short _cw;
+
+ __fnstcw(&_cw);
+ return ((_cw & FP_PRC_FLD) >> FP_PRC_OFF);
+}
+
+static __inline__ fp_rnd_t
+fpsetprec(fp_rnd_t _m)
{
- unsigned short _mem;
+ unsigned short _cw;
+ fp_prec_t _p;
- /*-
- * This is more efficient than it looks. The switch gets optimized
- * away if _reg is constant.
- *
- * The default case only supports _reg == 0. We could handle more
- * registers (e.g., tags) using fnstenv, but the interface doesn't
- * support more.
- */
- switch(_reg) {
- default:
- __fnstcw(&_mem);
- break;
- case FP_STKY_REG:
- __fnstsw(&_mem);
- break;
- }
- return _mem;
+ __fnstcw(&_cw);
+ _p = (_cw & FP_PRC_FLD) >> FP_PRC_OFF;
+ _cw &= ~FP_PRC_FLD;
+ _cw |= (_m << FP_PRC_OFF) & FP_PRC_FLD;
+ __fldcw(&_cw);
+ return (_p);
}
/*
- * set a FP mode; return previous mode
+ * Look at the exception masks
+ * Note that x87 masks are inverse of the fp*() functions
+ * API. ie: mask = 1 means disable for x87 and SSE, but
+ * for the fp*() api, mask = 1 means enabled.
*/
-static __inline__ int
-__fpsetreg(int _m, int _reg, int _fld, int _off)
+static __inline__ fp_except_t
+fpgetmask(void)
+{
+ unsigned short _cw;
+
+ __fnstcw(&_cw);
+ return ((~_cw) & FP_MSKS_FLD);
+}
+
+static __inline__ fp_except_t
+fpsetmask(fp_except_t _m)
+{
+ unsigned short _cw;
+ unsigned int _mxcsr;
+ fp_except_t _p;
+
+ __fnstcw(&_cw);
+ _p = (~_cw) & FP_MSKS_FLD;
+ _cw ~= ~FP_MSKS_FLD;
+ _cw |= (~_m) & FP_MSKS_FLD;
+ __fldcw(&_cw);
+ __stmxcsr(&_mxcxr);
+ /* XXX should clear non-ieee SSE_DAZ_FLD and SSE_FZ_FLD */
+ _mxcsr &= ~SSE_MSKS_FLD;
+ _mxcsr |= ((~_m) << SSE_MSKS_OFF) & SSE_MSKS_FLD);
+ __ldmxcsr(&_mxcsr);
+ return (_p);
+}
+
+/* See which sticky exceptions are pending, and reset them */
+static __inline__ fp_except_t
+fpgetsticky(void)
+{
+ unsigned short _sw;
+ unsigned int _mxcsr;
+ fp_except_t _ex;
+
+ __fnstsw(&_sw);
+ _ex = _sw & FP_STKY_FLD;
+ __stmxcsr(&_mxcsr);
+ _ex |= _mxcsr & SSE_STKY_FLD;
+ return (_ex);
+}
+
+static __inline__ fp_except_t
+fpresetsticky(fp_except_t _m)
{
unsigned _env[7];
- unsigned _p;
+ unsigned int _mxcsr;
+ fp_except_t _p;
- /*
- * _reg == 0 could be handled better using fnstcw/fldcw.
- */
__fnstenv(_env);
- _p = (_env[_reg] & _fld) >> _off;
- _env[_reg] = (_env[_reg] & ~_fld) | (_m << _off & _fld);
+ _p = _env[FP_STKY_REG] & _m;
+ __stmxcsr(&_mxcsr);
+ _p |= _mxcsr & SSE_STKY_FLD;
+ _env[FP_STKY_REG] &= ~_m;
__fldenv(_env);
- return _p;
+ _mxcsr &= ~_m;
+ __ldmxcsr(&_mxcsr);
+ return (_p);
}
-#endif /* __GNUC__ */
-
-/*
- * SysV/386 FP control interface
- */
-#define fpgetround() ((fp_rnd_t) \
- ((__fpgetreg(FP_RND_REG) & FP_RND_FLD) >> FP_RND_OFF))
-#define fpsetround(m) ((fp_rnd_t) \
- __fpsetreg((m), FP_RND_REG, FP_RND_FLD, FP_RND_OFF))
-#define fpgetprec() ((fp_prec_t) \
- ((__fpgetreg(FP_PRC_REG) & FP_PRC_FLD) >> FP_PRC_OFF))
-#define fpsetprec(m) ((fp_prec_t) \
- __fpsetreg((m), FP_PRC_REG, FP_PRC_FLD, FP_PRC_OFF))
-#define fpgetmask() ((fp_except_t) \
- ((~__fpgetreg(FP_MSKS_REG) & FP_MSKS_FLD) >> FP_MSKS_OFF))
-#define fpsetmask(m) ((fp_except_t) \
- (~__fpsetreg(~(m), FP_MSKS_REG, FP_MSKS_FLD, FP_MSKS_OFF)) & \
- (FP_MSKS_FLD >> FP_MSKS_OFF))
-#define fpgetsticky() ((fp_except_t) \
- ((__fpgetreg(FP_STKY_REG) & FP_STKY_FLD) >> FP_STKY_OFF))
-#define fpresetsticky(m) ((fp_except_t) \
- __fpsetreg(0, FP_STKY_REG, (m), FP_STKY_OFF))
+/* It is called fpsetsticky(), but is really a reset function */
#define fpsetsticky(m) fpresetsticky(m)
/* Suppress prototypes in the MI header. */
#define _IEEEFP_INLINED_ 1
+#endif /* __GNUC__ */
+
#endif /* !_MACHINE_IEEEFP_H_ */
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