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ARM FP16 support

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Implement the ARM VFP half precision floating point extensions.

Signed-off-by: Paul Brook <paul@codesourcery.com>
This commit is contained in:
Paul Brook 2009-11-19 16:45:20 +00:00
parent f165b53a89
commit 600114988c
6 changed files with 249 additions and 0 deletions
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138
fpu/softfloat.c
View File

@ -2457,6 +2457,144 @@ float32 float64_to_float32( float64 a STATUS_PARAM )
}
/*----------------------------------------------------------------------------
| Packs the sign `zSign', exponent `zExp', and significand `zSig' into a
| half-precision floating-point value, returning the result. After being
| shifted into the proper positions, the three fields are simply added
| together to form the result. This means that any integer portion of `zSig'
| will be added into the exponent. Since a properly normalized significand
| will have an integer portion equal to 1, the `zExp' input should be 1 less
| than the desired result exponent whenever `zSig' is a complete, normalized
| significand.
*----------------------------------------------------------------------------*/
static bits16 packFloat16(flag zSign, int16 zExp, bits16 zSig)
{
return (((bits32)zSign) << 15) + (((bits32)zExp) << 10) + zSig;
}
/* Half precision floats come in two formats: standard IEEE and "ARM" format.
The latter gains extra exponent range by omitting the NaN/Inf encodings. */
float32 float16_to_float32( bits16 a, flag ieee STATUS_PARAM )
{
flag aSign;
int16 aExp;
bits32 aSig;
aSign = a >> 15;
aExp = (a >> 10) & 0x1f;
aSig = a & 0x3ff;
if (aExp == 0x1f && ieee) {
if (aSig) {
/* Make sure correct exceptions are raised. */
float32ToCommonNaN(a STATUS_VAR);
aSig |= 0x200;
}
return packFloat32(aSign, 0xff, aSig << 13);
}
if (aExp == 0) {
int8 shiftCount;
if (aSig == 0) {
return packFloat32(aSign, 0, 0);
}
shiftCount = countLeadingZeros32( aSig ) - 21;
aSig = aSig << shiftCount;
aExp = -shiftCount;
}
return packFloat32( aSign, aExp + 0x70, aSig << 13);
}
bits16 float32_to_float16( float32 a, flag ieee STATUS_PARAM)
{
flag aSign;
int16 aExp;
bits32 aSig;
bits32 mask;
bits32 increment;
int8 roundingMode;
aSig = extractFloat32Frac( a );
aExp = extractFloat32Exp( a );
aSign = extractFloat32Sign( a );
if ( aExp == 0xFF ) {
if (aSig) {
/* Make sure correct exceptions are raised. */
float32ToCommonNaN(a STATUS_VAR);
aSig |= 0x00400000;
}
return packFloat16(aSign, 0x1f, aSig >> 13);
}
if (aExp == 0 && aSign == 0) {
return packFloat16(aSign, 0, 0);
}
/* Decimal point between bits 22 and 23. */
aSig |= 0x00800000;
aExp -= 0x7f;
if (aExp < -14) {
mask = 0x007fffff;
if (aExp < -24) {
aExp = -25;
} else {
mask >>= 24 + aExp;
}
} else {
mask = 0x00001fff;
}
if (aSig & mask) {
float_raise( float_flag_underflow STATUS_VAR );
roundingMode = STATUS(float_rounding_mode);
switch (roundingMode) {
case float_round_nearest_even:
increment = (mask + 1) >> 1;
if ((aSig & mask) == increment) {
increment = aSig & (increment << 1);
}
break;
case float_round_up:
increment = aSign ? 0 : mask;
break;
case float_round_down:
increment = aSign ? mask : 0;
break;
default: /* round_to_zero */
increment = 0;
break;
}
aSig += increment;
if (aSig >= 0x01000000) {
aSig >>= 1;
aExp++;
}
} else if (aExp < -14
&& STATUS(float_detect_tininess) == float_tininess_before_rounding) {
float_raise( float_flag_underflow STATUS_VAR);
}
if (ieee) {
if (aExp > 15) {
float_raise( float_flag_overflow | float_flag_inexact STATUS_VAR);
return packFloat16(aSign, 0x1f, 0);
}
} else {
if (aExp > 16) {
float_raise( float_flag_overflow | float_flag_inexact STATUS_VAR);
return packFloat16(aSign, 0x1f, 0x3ff);
}
}
if (aExp < -24) {
return packFloat16(aSign, 0, 0);
}
if (aExp < -14) {
aSig >>= -14 - aExp;
aExp = -14;
}
return packFloat16(aSign, aExp + 14, aSig >> 13);
}
#ifdef FLOATX80
/*----------------------------------------------------------------------------

6
fpu/softfloat.h
View File

@ -242,6 +242,12 @@ floatx80 int64_to_floatx80( int64_t STATUS_PARAM );
float128 int64_to_float128( int64_t STATUS_PARAM );
#endif
/*----------------------------------------------------------------------------
| Software half-precision conversion routines.
*----------------------------------------------------------------------------*/
bits16 float32_to_float16( float32, flag STATUS_PARAM );
float32 float16_to_float32( bits16, flag STATUS_PARAM );
/*----------------------------------------------------------------------------
| Software IEC/IEEE single-precision conversion routines.
*----------------------------------------------------------------------------*/

1
target-arm/cpu.h
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@ -337,6 +337,7 @@ enum arm_features {
ARM_FEATURE_THUMB2,
ARM_FEATURE_MPU, /* Only has Memory Protection Unit, not full MMU. */
ARM_FEATURE_VFP3,
ARM_FEATURE_VFP_FP16,
ARM_FEATURE_NEON,
ARM_FEATURE_DIV,
ARM_FEATURE_M, /* Microcontroller profile. */

16
target-arm/helper.c
View File

@ -115,6 +115,7 @@ static void cpu_reset_model_id(CPUARMState *env, uint32_t id)
set_feature(env, ARM_FEATURE_THUMB2);
set_feature(env, ARM_FEATURE_VFP);
set_feature(env, ARM_FEATURE_VFP3);
set_feature(env, ARM_FEATURE_VFP_FP16);
set_feature(env, ARM_FEATURE_NEON);
set_feature(env, ARM_FEATURE_THUMB2EE);
set_feature(env, ARM_FEATURE_DIV);
@ -2568,6 +2569,21 @@ VFP_CONV_FIX(uh, s, float32, uint16, u)
VFP_CONV_FIX(ul, s, float32, uint32, u)
#undef VFP_CONV_FIX
/* Half precision conversions. */
float32 HELPER(vfp_fcvt_f16_to_f32)(uint32_t a, CPUState *env)
{
float_status *s = &env->vfp.fp_status;
int ieee = (env->vfp.xregs[ARM_VFP_FPSCR] & (1 << 26)) == 0;
return float16_to_float32(a, ieee, s);
}
uint32_t HELPER(vfp_fcvt_f32_to_f16)(float32 a, CPUState *env)
{
float_status *s = &env->vfp.fp_status;
int ieee = (env->vfp.xregs[ARM_VFP_FPSCR] & (1 << 26)) == 0;
return float32_to_float16(a, ieee, s);
}
float32 HELPER(recps_f32)(float32 a, float32 b, CPUState *env)
{
float_status *s = &env->vfp.fp_status;

3
target-arm/helpers.h
View File

@ -131,6 +131,9 @@ DEF_HELPER_3(vfp_sltod, f64, f64, i32, env)
DEF_HELPER_3(vfp_uhtod, f64, f64, i32, env)
DEF_HELPER_3(vfp_ultod, f64, f64, i32, env)
DEF_HELPER_2(vfp_fcvt_f16_to_f32, f32, i32, env)
DEF_HELPER_2(vfp_fcvt_f32_to_f16, i32, f32, env)
DEF_HELPER_3(recps_f32, f32, f32, f32, env)
DEF_HELPER_3(rsqrts_f32, f32, f32, f32, env)
DEF_HELPER_2(recpe_f32, f32, f32, env)

85
target-arm/translate.c
View File

@ -2974,6 +2974,47 @@ static int disas_vfp_insn(CPUState * env, DisasContext *s, uint32_t insn)
case 3: /* sqrt */
gen_vfp_sqrt(dp);
break;
case 4: /* vcvtb.f32.f16 */
if (!arm_feature(env, ARM_FEATURE_VFP_FP16))
return 1;
tmp = gen_vfp_mrs();
tcg_gen_ext16u_i32(tmp, tmp);
gen_helper_vfp_fcvt_f16_to_f32(cpu_F0s, tmp, cpu_env);
dead_tmp(tmp);
break;
case 5: /* vcvtt.f32.f16 */
if (!arm_feature(env, ARM_FEATURE_VFP_FP16))
return 1;
tmp = gen_vfp_mrs();
tcg_gen_shri_i32(tmp, tmp, 16);
gen_helper_vfp_fcvt_f16_to_f32(cpu_F0s, tmp, cpu_env);
dead_tmp(tmp);
break;
case 6: /* vcvtb.f16.f32 */
if (!arm_feature(env, ARM_FEATURE_VFP_FP16))
return 1;
tmp = new_tmp();
gen_helper_vfp_fcvt_f32_to_f16(tmp, cpu_F0s, cpu_env);
gen_mov_F0_vreg(0, rd);
tmp2 = gen_vfp_mrs();
tcg_gen_andi_i32(tmp2, tmp2, 0xffff0000);
tcg_gen_or_i32(tmp, tmp, tmp2);
dead_tmp(tmp2);
gen_vfp_msr(tmp);
break;
case 7: /* vcvtt.f16.f32 */
if (!arm_feature(env, ARM_FEATURE_VFP_FP16))
return 1;
tmp = new_tmp();
gen_helper_vfp_fcvt_f32_to_f16(tmp, cpu_F0s, cpu_env);
tcg_gen_shli_i32(tmp, tmp, 16);
gen_mov_F0_vreg(0, rd);
tmp2 = gen_vfp_mrs();
tcg_gen_ext16u_i32(tmp2, tmp2);
tcg_gen_or_i32(tmp, tmp, tmp2);
dead_tmp(tmp2);
gen_vfp_msr(tmp);
break;
case 8: /* cmp */
gen_vfp_cmp(dp);
break;
@ -5328,6 +5369,50 @@ static int disas_neon_data_insn(CPUState * env, DisasContext *s, uint32_t insn)
neon_store_reg64(cpu_V0, rd + pass);
}
break;
case 44: /* VCVT.F16.F32 */
if (!arm_feature(env, ARM_FEATURE_VFP_FP16))
return 1;
tmp = new_tmp();
tmp2 = new_tmp();
tcg_gen_ld_f32(cpu_F0s, cpu_env, neon_reg_offset(rm, 0));
gen_helper_vfp_fcvt_f32_to_f16(tmp, cpu_F0s, cpu_env);
tcg_gen_ld_f32(cpu_F0s, cpu_env, neon_reg_offset(rm, 1));
gen_helper_vfp_fcvt_f32_to_f16(tmp2, cpu_F0s, cpu_env);
tcg_gen_shli_i32(tmp2, tmp2, 16);
tcg_gen_or_i32(tmp2, tmp2, tmp);
tcg_gen_ld_f32(cpu_F0s, cpu_env, neon_reg_offset(rm, 2));
gen_helper_vfp_fcvt_f32_to_f16(tmp, cpu_F0s, cpu_env);
tcg_gen_ld_f32(cpu_F0s, cpu_env, neon_reg_offset(rm, 3));
neon_store_reg(rd, 0, tmp2);
tmp2 = new_tmp();
gen_helper_vfp_fcvt_f32_to_f16(tmp2, cpu_F0s, cpu_env);
tcg_gen_shli_i32(tmp2, tmp2, 16);
tcg_gen_or_i32(tmp2, tmp2, tmp);
neon_store_reg(rd, 1, tmp2);
dead_tmp(tmp);
break;
case 46: /* VCVT.F32.F16 */
if (!arm_feature(env, ARM_FEATURE_VFP_FP16))
return 1;
tmp3 = new_tmp();
tmp = neon_load_reg(rm, 0);
tmp2 = neon_load_reg(rm, 1);
tcg_gen_ext16u_i32(tmp3, tmp);
gen_helper_vfp_fcvt_f16_to_f32(cpu_F0s, tmp3, cpu_env);
tcg_gen_st_f32(cpu_F0s, cpu_env, neon_reg_offset(rd, 0));
tcg_gen_shri_i32(tmp3, tmp, 16);
gen_helper_vfp_fcvt_f16_to_f32(cpu_F0s, tmp3, cpu_env);
tcg_gen_st_f32(cpu_F0s, cpu_env, neon_reg_offset(rd, 1));
dead_tmp(tmp);
tcg_gen_ext16u_i32(tmp3, tmp2);
gen_helper_vfp_fcvt_f16_to_f32(cpu_F0s, tmp3, cpu_env);
tcg_gen_st_f32(cpu_F0s, cpu_env, neon_reg_offset(rd, 2));
tcg_gen_shri_i32(tmp3, tmp2, 16);
gen_helper_vfp_fcvt_f16_to_f32(cpu_F0s, tmp3, cpu_env);
tcg_gen_st_f32(cpu_F0s, cpu_env, neon_reg_offset(rd, 3));
dead_tmp(tmp2);
dead_tmp(tmp3);
break;
default:
elementwise:
for (pass = 0; pass < (q ? 4 : 2); pass++) {