On Tue, 9 Dec 2014, Maciej W. Rozycki wrote:
> Index: qemu-git-trunk/target-mips/op_helper.c
> ===================================================================
> --- qemu-git-trunk.orig/target-mips/op_helper.c 2014-12-08
> 23:22:12.000000000 +0000
> +++ qemu-git-trunk/target-mips/op_helper.c 2014-12-08 23:25:02.558929097
> +0000
> @@ -2274,8 +2274,12 @@ void mips_cpu_unassigned_access(CPUState
>
> #define FLOAT_TWO32 make_float32(1 << 30)
> #define FLOAT_TWO64 make_float64(1ULL << 62)
> -#define FP_TO_INT32_OVERFLOW 0x7fffffff
> -#define FP_TO_INT64_OVERFLOW 0x7fffffffffffffffULL
> +#define FLOAT_INAN32(env) \
> + (((env)->active_fpu.fcr31 & (1 << FCR31_NAN2008)) \
> + ? 0x00000000 : 0x7fffffff)
> +#define FLOAT_INAN64(env) \
> + (((env)->active_fpu.fcr31 & (1 << FCR31_NAN2008)) \
> + ? 0x0000000000000000ULL : 0x7fffffffffffffffULL)
>
> /* convert MIPS rounding mode in FCR31 to IEEE library */
> unsigned int ieee_rm[] = {
[...]
> @@ -2481,7 +2482,7 @@ uint64_t helper_float_cvtl_d(CPUMIPSStat
> dt2 = float64_to_int64(fdt0, &env->active_fpu.fp_status);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - dt2 = FP_TO_INT64_OVERFLOW;
> + dt2 = FLOAT_INAN64(env);
> }
> update_fcr31(env, GETPC());
> return dt2;
> @@ -2494,7 +2495,7 @@ uint64_t helper_float_cvtl_s(CPUMIPSStat
> dt2 = float32_to_int64(fst0, &env->active_fpu.fp_status);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - dt2 = FP_TO_INT64_OVERFLOW;
> + dt2 = FLOAT_INAN64(env);
> }
> update_fcr31(env, GETPC());
> return dt2;
> @@ -2520,14 +2521,14 @@ uint64_t helper_float_cvtpw_ps(CPUMIPSSt
> wt2 = float32_to_int32(fdt0 & 0XFFFFFFFF, &env->active_fpu.fp_status);
> excp = get_float_exception_flags(&env->active_fpu.fp_status);
> if (excp & (float_flag_overflow | float_flag_invalid)) {
> - wt2 = FP_TO_INT32_OVERFLOW;
> + wt2 = FLOAT_INAN32(env);
> }
>
> set_float_exception_flags(0, &env->active_fpu.fp_status);
> wth2 = float32_to_int32(fdt0 >> 32, &env->active_fpu.fp_status);
> excph = get_float_exception_flags(&env->active_fpu.fp_status);
> if (excph & (float_flag_overflow | float_flag_invalid)) {
> - wth2 = FP_TO_INT32_OVERFLOW;
> + wth2 = FLOAT_INAN32(env);
> }
>
> set_float_exception_flags(excp | excph, &env->active_fpu.fp_status);
> @@ -2588,7 +2589,7 @@ uint32_t helper_float_cvtw_s(CPUMIPSStat
> wt2 = float32_to_int32(fst0, &env->active_fpu.fp_status);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - wt2 = FP_TO_INT32_OVERFLOW;
> + wt2 = FLOAT_INAN32(env);
> }
> update_fcr31(env, GETPC());
> return wt2;
> @@ -2601,7 +2602,7 @@ uint32_t helper_float_cvtw_d(CPUMIPSStat
> wt2 = float64_to_int32(fdt0, &env->active_fpu.fp_status);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - wt2 = FP_TO_INT32_OVERFLOW;
> + wt2 = FLOAT_INAN32(env);
> }
> update_fcr31(env, GETPC());
> return wt2;
> @@ -2616,7 +2617,7 @@ uint64_t helper_float_roundl_d(CPUMIPSSt
> restore_rounding_mode(env);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - dt2 = FP_TO_INT64_OVERFLOW;
> + dt2 = FLOAT_INAN64(env);
> }
> update_fcr31(env, GETPC());
> return dt2;
> @@ -2631,7 +2632,7 @@ uint64_t helper_float_roundl_s(CPUMIPSSt
> restore_rounding_mode(env);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - dt2 = FP_TO_INT64_OVERFLOW;
> + dt2 = FLOAT_INAN64(env);
> }
> update_fcr31(env, GETPC());
> return dt2;
> @@ -2646,7 +2647,7 @@ uint32_t helper_float_roundw_d(CPUMIPSSt
> restore_rounding_mode(env);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - wt2 = FP_TO_INT32_OVERFLOW;
> + wt2 = FLOAT_INAN32(env);
> }
> update_fcr31(env, GETPC());
> return wt2;
> @@ -2661,7 +2662,7 @@ uint32_t helper_float_roundw_s(CPUMIPSSt
> restore_rounding_mode(env);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - wt2 = FP_TO_INT32_OVERFLOW;
> + wt2 = FLOAT_INAN32(env);
> }
> update_fcr31(env, GETPC());
> return wt2;
> @@ -2674,7 +2675,7 @@ uint64_t helper_float_truncl_d(CPUMIPSSt
> dt2 = float64_to_int64_round_to_zero(fdt0, &env->active_fpu.fp_status);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - dt2 = FP_TO_INT64_OVERFLOW;
> + dt2 = FLOAT_INAN64(env);
> }
> update_fcr31(env, GETPC());
> return dt2;
> @@ -2687,7 +2688,7 @@ uint64_t helper_float_truncl_s(CPUMIPSSt
> dt2 = float32_to_int64_round_to_zero(fst0, &env->active_fpu.fp_status);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - dt2 = FP_TO_INT64_OVERFLOW;
> + dt2 = FLOAT_INAN64(env);
> }
> update_fcr31(env, GETPC());
> return dt2;
> @@ -2700,7 +2701,7 @@ uint32_t helper_float_truncw_d(CPUMIPSSt
> wt2 = float64_to_int32_round_to_zero(fdt0, &env->active_fpu.fp_status);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - wt2 = FP_TO_INT32_OVERFLOW;
> + wt2 = FLOAT_INAN32(env);
> }
> update_fcr31(env, GETPC());
> return wt2;
> @@ -2713,7 +2714,7 @@ uint32_t helper_float_truncw_s(CPUMIPSSt
> wt2 = float32_to_int32_round_to_zero(fst0, &env->active_fpu.fp_status);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - wt2 = FP_TO_INT32_OVERFLOW;
> + wt2 = FLOAT_INAN32(env);
> }
> update_fcr31(env, GETPC());
> return wt2;
> @@ -2728,7 +2729,7 @@ uint64_t helper_float_ceill_d(CPUMIPSSta
> restore_rounding_mode(env);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - dt2 = FP_TO_INT64_OVERFLOW;
> + dt2 = FLOAT_INAN64(env);
> }
> update_fcr31(env, GETPC());
> return dt2;
> @@ -2743,7 +2744,7 @@ uint64_t helper_float_ceill_s(CPUMIPSSta
> restore_rounding_mode(env);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - dt2 = FP_TO_INT64_OVERFLOW;
> + dt2 = FLOAT_INAN64(env);
> }
> update_fcr31(env, GETPC());
> return dt2;
> @@ -2758,7 +2759,7 @@ uint32_t helper_float_ceilw_d(CPUMIPSSta
> restore_rounding_mode(env);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - wt2 = FP_TO_INT32_OVERFLOW;
> + wt2 = FLOAT_INAN32(env);
> }
> update_fcr31(env, GETPC());
> return wt2;
> @@ -2773,7 +2774,7 @@ uint32_t helper_float_ceilw_s(CPUMIPSSta
> restore_rounding_mode(env);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - wt2 = FP_TO_INT32_OVERFLOW;
> + wt2 = FLOAT_INAN32(env);
> }
> update_fcr31(env, GETPC());
> return wt2;
> @@ -2788,7 +2789,7 @@ uint64_t helper_float_floorl_d(CPUMIPSSt
> restore_rounding_mode(env);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - dt2 = FP_TO_INT64_OVERFLOW;
> + dt2 = FLOAT_INAN64(env);
> }
> update_fcr31(env, GETPC());
> return dt2;
> @@ -2803,7 +2804,7 @@ uint64_t helper_float_floorl_s(CPUMIPSSt
> restore_rounding_mode(env);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - dt2 = FP_TO_INT64_OVERFLOW;
> + dt2 = FLOAT_INAN64(env);
> }
> update_fcr31(env, GETPC());
> return dt2;
> @@ -2818,7 +2819,7 @@ uint32_t helper_float_floorw_d(CPUMIPSSt
> restore_rounding_mode(env);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - wt2 = FP_TO_INT32_OVERFLOW;
> + wt2 = FLOAT_INAN32(env);
> }
> update_fcr31(env, GETPC());
> return wt2;
> @@ -2833,23 +2834,23 @@ uint32_t helper_float_floorw_s(CPUMIPSSt
> restore_rounding_mode(env);
> if (get_float_exception_flags(&env->active_fpu.fp_status)
> & (float_flag_invalid | float_flag_overflow)) {
> - wt2 = FP_TO_INT32_OVERFLOW;
> + wt2 = FLOAT_INAN32(env);
> }
> update_fcr31(env, GETPC());
> return wt2;
I have realised these all need a further update to follow the
architecture specification correctly in the 2008-NaN mode. This is
because in the legacy-NaN mode a single value of `maxint' is returned for
all invalid operations, however in the 2008-NaN mode distinct values are
returned depending of the nature of the invalidity as follows [1][2]:
* `minint' -- for negative operand overflows,
* 0 -- for NaN operands,
* `maxint' -- for positive operand overflows.
(note that the values required here were changed between revisions 3.50
and 5.00 of the architecture specifications). It should be
straightforward to implement as `float64_to_int64', etc. already return
the correct values for overflows, so it's only NaN operands that need a
fixup similar to the above, in the 2008-NaN mode.
Additionally the reference to the `float_flag_overflow' flag can and IMO
should be removed here, it's never set for conversions to a fixed-point
integer format.
References:
[1] "MIPS Architecture For Programmers, Volume I-A: Introduction to the
MIPS32 Architecture", MIPS Technologies, Inc., Document Number:
MD00082, Revision 5.00, December 14, 2012, Table 5.3 "Value Supplied
When a New Quiet NaN Is Created", p. 72
[2] "MIPS Architecture For Programmers, Volume I-A: Introduction to the
MIPS64 Architecture", MIPS Technologies, Inc., Document Number:
MD00083, Revision 5.00, December 14, 2012, Table 5.3 "Value Supplied
When a New Quiet NaN Is Created", p. 74
Maciej
