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[2001:8b0:1d0::2]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-438dcc81d74sm127401525e9.37.2025.02.01.08.40.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 01 Feb 2025 08:40:47 -0800 (PST) From: Peter Maydell To: qemu-arm@nongnu.org, qemu-devel@nongnu.org Subject: [PATCH v2 24/69] target/arm: Implement FPCR.AH semantics for scalar FMIN/FMAX Date: Sat, 1 Feb 2025 16:39:27 +0000 Message-Id: <20250201164012.1660228-25-peter.maydell@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250201164012.1660228-1-peter.maydell@linaro.org> References: <20250201164012.1660228-1-peter.maydell@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::32c; envelope-from=peter.maydell@linaro.org; helo=mail-wm1-x32c.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: qemu-devel-bounces+patch=linaro.org@nongnu.org When FPCR.AH == 1, floating point FMIN and FMAX have some odd special cases: * comparing two zeroes (even of different sign) or comparing a NaN with anything always returns the second argument (possibly squashed to zero) * denormal outputs are not squashed to zero regardless of FZ or FZ16 Implement these semantics in new helper functions and select them at translate time if FPCR.AH is 1 for the scalar FMAX and FMIN insns. (We will convert the other FMAX and FMIN insns in subsequent commits.) Note that FMINNM and FMAXNM are not affected. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson --- target/arm/tcg/helper-a64.h | 7 +++++++ target/arm/tcg/helper-a64.c | 36 ++++++++++++++++++++++++++++++++++ target/arm/tcg/translate-a64.c | 23 ++++++++++++++++++++-- 3 files changed, 64 insertions(+), 2 deletions(-) diff --git a/target/arm/tcg/helper-a64.h b/target/arm/tcg/helper-a64.h index bac12fbe55b..ae0424f6de9 100644 --- a/target/arm/tcg/helper-a64.h +++ b/target/arm/tcg/helper-a64.h @@ -67,6 +67,13 @@ DEF_HELPER_4(advsimd_muladd2h, i32, i32, i32, i32, fpst) DEF_HELPER_2(advsimd_rinth_exact, f16, f16, fpst) DEF_HELPER_2(advsimd_rinth, f16, f16, fpst) +DEF_HELPER_3(vfp_ah_minh, f16, f16, f16, fpst) +DEF_HELPER_3(vfp_ah_mins, f32, f32, f32, fpst) +DEF_HELPER_3(vfp_ah_mind, f64, f64, f64, fpst) +DEF_HELPER_3(vfp_ah_maxh, f16, f16, f16, fpst) +DEF_HELPER_3(vfp_ah_maxs, f32, f32, f32, fpst) +DEF_HELPER_3(vfp_ah_maxd, f64, f64, f64, fpst) + DEF_HELPER_2(exception_return, void, env, i64) DEF_HELPER_FLAGS_2(dc_zva, TCG_CALL_NO_WG, void, env, i64) diff --git a/target/arm/tcg/helper-a64.c b/target/arm/tcg/helper-a64.c index 05036089dd7..ed5e4a45997 100644 --- a/target/arm/tcg/helper-a64.c +++ b/target/arm/tcg/helper-a64.c @@ -399,6 +399,42 @@ float32 HELPER(fcvtx_f64_to_f32)(float64 a, float_status *fpst) return r; } +/* + * AH=1 min/max have some odd special cases: + * comparing two zeroes (regardless of sign), (NaN, anything), + * or (anything, NaN) should return the second argument (possibly + * squashed to zero). + * Also, denormal outputs are not squashed to zero regardless of FZ or FZ16. + */ +#define AH_MINMAX_HELPER(NAME, CTYPE, FLOATTYPE, MINMAX) \ + CTYPE HELPER(NAME)(CTYPE a, CTYPE b, float_status *fpst) \ + { \ + bool save; \ + CTYPE r; \ + a = FLOATTYPE ## _squash_input_denormal(a, fpst); \ + b = FLOATTYPE ## _squash_input_denormal(b, fpst); \ + if (FLOATTYPE ## _is_zero(a) && FLOATTYPE ## _is_zero(b)) { \ + return b; \ + } \ + if (FLOATTYPE ## _is_any_nan(a) || \ + FLOATTYPE ## _is_any_nan(b)) { \ + float_raise(float_flag_invalid, fpst); \ + return b; \ + } \ + save = get_flush_to_zero(fpst); \ + set_flush_to_zero(false, fpst); \ + r = FLOATTYPE ## _ ## MINMAX(a, b, fpst); \ + set_flush_to_zero(save, fpst); \ + return r; \ + } + +AH_MINMAX_HELPER(vfp_ah_minh, dh_ctype_f16, float16, min) +AH_MINMAX_HELPER(vfp_ah_mins, float32, float32, min) +AH_MINMAX_HELPER(vfp_ah_mind, float64, float64, min) +AH_MINMAX_HELPER(vfp_ah_maxh, dh_ctype_f16, float16, max) +AH_MINMAX_HELPER(vfp_ah_maxs, float32, float32, max) +AH_MINMAX_HELPER(vfp_ah_maxd, float64, float64, max) + /* 64-bit versions of the CRC helpers. Note that although the operation * (and the prototypes of crc32c() and crc32() mean that only the bottom * 32 bits of the accumulator and result are used, we pass and return diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c index 334aff42753..ae3f3d32f45 100644 --- a/target/arm/tcg/translate-a64.c +++ b/target/arm/tcg/translate-a64.c @@ -5152,6 +5152,15 @@ static bool do_fp3_scalar_ah(DisasContext *s, arg_rrr_e *a, const FPScalar *f, select_ah_fpst(s, a->esz)); } +/* Some insns need to call different helpers when FPCR.AH == 1 */ +static bool do_fp3_scalar_2fn(DisasContext *s, arg_rrr_e *a, + const FPScalar *fnormal, + const FPScalar *fah, + int mergereg) +{ + return do_fp3_scalar(s, a, s->fpcr_ah ? fah : fnormal, mergereg); +} + static const FPScalar f_scalar_fadd = { gen_helper_vfp_addh, gen_helper_vfp_adds, @@ -5185,14 +5194,24 @@ static const FPScalar f_scalar_fmax = { gen_helper_vfp_maxs, gen_helper_vfp_maxd, }; -TRANS(FMAX_s, do_fp3_scalar, a, &f_scalar_fmax, a->rn) +static const FPScalar f_scalar_fmax_ah = { + gen_helper_vfp_ah_maxh, + gen_helper_vfp_ah_maxs, + gen_helper_vfp_ah_maxd, +}; +TRANS(FMAX_s, do_fp3_scalar_2fn, a, &f_scalar_fmax, &f_scalar_fmax_ah, a->rn) static const FPScalar f_scalar_fmin = { gen_helper_vfp_minh, gen_helper_vfp_mins, gen_helper_vfp_mind, }; -TRANS(FMIN_s, do_fp3_scalar, a, &f_scalar_fmin, a->rn) +static const FPScalar f_scalar_fmin_ah = { + gen_helper_vfp_ah_minh, + gen_helper_vfp_ah_mins, + gen_helper_vfp_ah_mind, +}; +TRANS(FMIN_s, do_fp3_scalar_2fn, a, &f_scalar_fmin, &f_scalar_fmin_ah, a->rn) static const FPScalar f_scalar_fmaxnm = { gen_helper_vfp_maxnumh,