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[2001:8b0:1d0::2]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-42bb6e355dfsm232251365e9.46.2024.09.05.06.01.06 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Sep 2024 06:01:07 -0700 (PDT) From: Peter Maydell To: qemu-devel@nongnu.org Subject: [PULL 06/25] target/arm: Prepare bfdotadd() callers for FEAT_EBF support Date: Thu, 5 Sep 2024 14:00:41 +0100 Message-Id: <20240905130100.298768-7-peter.maydell@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240905130100.298768-1-peter.maydell@linaro.org> References: <20240905130100.298768-1-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, T_SCC_BODY_TEXT_LINE=-0.01 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org We use bfdotadd() in four callsites for various helper functions. Currently this all assumes that we have the FPCR.EBF=0 semantics. For FPCR.EBF=1 we will need to: * call a different routine to bfdotadd() because we need to do a fused multiply-add rather than separate multiply and add steps * use a different float_status that honours the FPCR rounding mode and denormal-flushing fields * pass in an extra float_status that has been set up to perform round-to-odd rounding To prepare for this, refactor all the callsites so that instead of for (...) { x = bfdotadd(...); } they are: float_status fpst, fpst_odd; if (is_ebf(env, &fpst, &fpst_odd)) { for (...) { x = bfdotadd_ebf(..., &fpst, &fpst_odd); } } else { for (...) { x = bfdotadd(..., &fpst); } } For the moment the is_ebf() function always returns false, sets up fpst for EBF=0 semantics and never sets up fpst_odd; bfdotadd_ebf() will assert if called. We'll fill in the handling for EBF=1 in the next commit. This change should be a zero-behaviour-change refactor. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson --- target/arm/tcg/vec_internal.h | 37 ++++++++- target/arm/tcg/sme_helper.c | 74 ++++++++++++------ target/arm/tcg/vec_helper.c | 139 +++++++++++++++++++++++++--------- 3 files changed, 189 insertions(+), 61 deletions(-) diff --git a/target/arm/tcg/vec_internal.h b/target/arm/tcg/vec_internal.h index 3ca1b94ccf9..094f5c169ca 100644 --- a/target/arm/tcg/vec_internal.h +++ b/target/arm/tcg/vec_internal.h @@ -223,13 +223,46 @@ int64_t do_sqrdmlah_d(int64_t, int64_t, int64_t, bool, bool); * bfdotadd: * @sum: addend * @e1, @e2: multiplicand vectors + * @fpst: floating-point status to use * * BFloat16 2-way dot product of @e1 & @e2, accumulating with @sum. * The @e1 and @e2 operands correspond to the 32-bit source vector * slots and contain two Bfloat16 values each. * - * Corresponds to the ARM pseudocode function BFDotAdd. + * Corresponds to the ARM pseudocode function BFDotAdd, specialized + * for the FPCR.EBF == 0 case. */ -float32 bfdotadd(float32 sum, uint32_t e1, uint32_t e2); +float32 bfdotadd(float32 sum, uint32_t e1, uint32_t e2, float_status *fpst); +/** + * bfdotadd_ebf: + * @sum: addend + * @e1, @e2: multiplicand vectors + * @fpst: floating-point status to use + * @fpst_odd: floating-point status to use for round-to-odd operations + * + * BFloat16 2-way dot product of @e1 & @e2, accumulating with @sum. + * The @e1 and @e2 operands correspond to the 32-bit source vector + * slots and contain two Bfloat16 values each. + * + * Corresponds to the ARM pseudocode function BFDotAdd, specialized + * for the FPCR.EBF == 1 case. + */ +float32 bfdotadd_ebf(float32 sum, uint32_t e1, uint32_t e2, + float_status *fpst, float_status *fpst_odd); + +/** + * is_ebf: + * @env: CPU state + * @statusp: pointer to floating point status to fill in + * @oddstatusp: pointer to floating point status to fill in for round-to-odd + * + * Determine whether a BFDotAdd operation should use FPCR.EBF = 0 + * or FPCR.EBF = 1 semantics. On return, has initialized *statusp + * and *oddstatusp to suitable float_status arguments to use with either + * bfdotadd() or bfdotadd_ebf(). + * Returns true for EBF = 1, false for EBF = 0. (The caller should use this + * to decide whether to call bfdotadd() or bfdotadd_ebf().) + */ +bool is_ebf(CPUARMState *env, float_status *statusp, float_status *oddstatusp); #endif /* TARGET_ARM_VEC_INTERNAL_H */ diff --git a/target/arm/tcg/sme_helper.c b/target/arm/tcg/sme_helper.c index 289ffabbfbe..8cf12654e56 100644 --- a/target/arm/tcg/sme_helper.c +++ b/target/arm/tcg/sme_helper.c @@ -1085,32 +1085,62 @@ void HELPER(sme_bfmopa)(void *vza, void *vzn, void *vzm, intptr_t row, col, oprsz = simd_maxsz(desc); uint32_t neg = simd_data(desc) * 0x80008000u; uint16_t *pn = vpn, *pm = vpm; + float_status fpst, fpst_odd; - for (row = 0; row < oprsz; ) { - uint16_t prow = pn[H2(row >> 4)]; - do { - void *vza_row = vza + tile_vslice_offset(row); - uint32_t n = *(uint32_t *)(vzn + H1_4(row)); + if (is_ebf(env, &fpst, &fpst_odd)) { + for (row = 0; row < oprsz; ) { + uint16_t prow = pn[H2(row >> 4)]; + do { + void *vza_row = vza + tile_vslice_offset(row); + uint32_t n = *(uint32_t *)(vzn + H1_4(row)); - n = f16mop_adj_pair(n, prow, neg); + n = f16mop_adj_pair(n, prow, neg); - for (col = 0; col < oprsz; ) { - uint16_t pcol = pm[H2(col >> 4)]; - do { - if (prow & pcol & 0b0101) { - uint32_t *a = vza_row + H1_4(col); - uint32_t m = *(uint32_t *)(vzm + H1_4(col)); + for (col = 0; col < oprsz; ) { + uint16_t pcol = pm[H2(col >> 4)]; + do { + if (prow & pcol & 0b0101) { + uint32_t *a = vza_row + H1_4(col); + uint32_t m = *(uint32_t *)(vzm + H1_4(col)); - m = f16mop_adj_pair(m, pcol, 0); - *a = bfdotadd(*a, n, m); - } - col += 4; - pcol >>= 4; - } while (col & 15); - } - row += 4; - prow >>= 4; - } while (row & 15); + m = f16mop_adj_pair(m, pcol, 0); + *a = bfdotadd_ebf(*a, n, m, &fpst, &fpst_odd); + } + col += 4; + pcol >>= 4; + } while (col & 15); + } + row += 4; + prow >>= 4; + } while (row & 15); + } + } else { + for (row = 0; row < oprsz; ) { + uint16_t prow = pn[H2(row >> 4)]; + do { + void *vza_row = vza + tile_vslice_offset(row); + uint32_t n = *(uint32_t *)(vzn + H1_4(row)); + + n = f16mop_adj_pair(n, prow, neg); + + for (col = 0; col < oprsz; ) { + uint16_t pcol = pm[H2(col >> 4)]; + do { + if (prow & pcol & 0b0101) { + uint32_t *a = vza_row + H1_4(col); + uint32_t m = *(uint32_t *)(vzm + H1_4(col)); + + m = f16mop_adj_pair(m, pcol, 0); + *a = bfdotadd(*a, n, m, &fpst); + } + col += 4; + pcol >>= 4; + } while (col & 15); + } + row += 4; + prow >>= 4; + } while (row & 15); + } } } diff --git a/target/arm/tcg/vec_helper.c b/target/arm/tcg/vec_helper.c index 616ec54bb77..b0de74b55f1 100644 --- a/target/arm/tcg/vec_helper.c +++ b/target/arm/tcg/vec_helper.c @@ -2790,39 +2790,58 @@ DO_MMLA_B(gvec_usmmla_b, do_usmmla_b) * BFloat16 Dot Product */ -float32 bfdotadd(float32 sum, uint32_t e1, uint32_t e2) +bool is_ebf(CPUARMState *env, float_status *statusp, float_status *oddstatusp) { /* FPCR is ignored for BFDOT and BFMMLA. */ - float_status bf_status = { + *statusp = (float_status){ .tininess_before_rounding = float_tininess_before_rounding, .float_rounding_mode = float_round_to_odd_inf, .flush_to_zero = true, .flush_inputs_to_zero = true, .default_nan_mode = true, }; + + return false; +} + +float32 bfdotadd(float32 sum, uint32_t e1, uint32_t e2, float_status *fpst) +{ float32 t1, t2; /* * Extract each BFloat16 from the element pair, and shift * them such that they become float32. */ - t1 = float32_mul(e1 << 16, e2 << 16, &bf_status); - t2 = float32_mul(e1 & 0xffff0000u, e2 & 0xffff0000u, &bf_status); - t1 = float32_add(t1, t2, &bf_status); - t1 = float32_add(sum, t1, &bf_status); + t1 = float32_mul(e1 << 16, e2 << 16, fpst); + t2 = float32_mul(e1 & 0xffff0000u, e2 & 0xffff0000u, fpst); + t1 = float32_add(t1, t2, fpst); + t1 = float32_add(sum, t1, fpst); return t1; } +float32 bfdotadd_ebf(float32 sum, uint32_t e1, uint32_t e2, + float_status *fpst, float_status *fpst_odd) +{ + g_assert_not_reached(); +} + void HELPER(gvec_bfdot)(void *vd, void *vn, void *vm, void *va, CPUARMState *env, uint32_t desc) { intptr_t i, opr_sz = simd_oprsz(desc); float32 *d = vd, *a = va; uint32_t *n = vn, *m = vm; + float_status fpst, fpst_odd; - for (i = 0; i < opr_sz / 4; ++i) { - d[i] = bfdotadd(a[i], n[i], m[i]); + if (is_ebf(env, &fpst, &fpst_odd)) { + for (i = 0; i < opr_sz / 4; ++i) { + d[i] = bfdotadd_ebf(a[i], n[i], m[i], &fpst, &fpst_odd); + } + } else { + for (i = 0; i < opr_sz / 4; ++i) { + d[i] = bfdotadd(a[i], n[i], m[i], &fpst); + } } clear_tail(d, opr_sz, simd_maxsz(desc)); } @@ -2836,12 +2855,23 @@ void HELPER(gvec_bfdot_idx)(void *vd, void *vn, void *vm, intptr_t eltspersegment = MIN(16 / 4, elements); float32 *d = vd, *a = va; uint32_t *n = vn, *m = vm; + float_status fpst, fpst_odd; - for (i = 0; i < elements; i += eltspersegment) { - uint32_t m_idx = m[i + H4(index)]; + if (is_ebf(env, &fpst, &fpst_odd)) { + for (i = 0; i < elements; i += eltspersegment) { + uint32_t m_idx = m[i + H4(index)]; - for (j = i; j < i + eltspersegment; j++) { - d[j] = bfdotadd(a[j], n[j], m_idx); + for (j = i; j < i + eltspersegment; j++) { + d[j] = bfdotadd_ebf(a[j], n[j], m_idx, &fpst, &fpst_odd); + } + } + } else { + for (i = 0; i < elements; i += eltspersegment) { + uint32_t m_idx = m[i + H4(index)]; + + for (j = i; j < i + eltspersegment; j++) { + d[j] = bfdotadd(a[j], n[j], m_idx, &fpst); + } } } clear_tail(d, opr_sz, simd_maxsz(desc)); @@ -2853,37 +2883,72 @@ void HELPER(gvec_bfmmla)(void *vd, void *vn, void *vm, void *va, intptr_t s, opr_sz = simd_oprsz(desc); float32 *d = vd, *a = va; uint32_t *n = vn, *m = vm; + float_status fpst, fpst_odd; - for (s = 0; s < opr_sz / 4; s += 4) { - float32 sum00, sum01, sum10, sum11; + if (is_ebf(env, &fpst, &fpst_odd)) { + for (s = 0; s < opr_sz / 4; s += 4) { + float32 sum00, sum01, sum10, sum11; - /* - * Process the entire segment at once, writing back the - * results only after we've consumed all of the inputs. - * - * Key to indices by column: - * i j i k j k - */ - sum00 = a[s + H4(0 + 0)]; - sum00 = bfdotadd(sum00, n[s + H4(0 + 0)], m[s + H4(0 + 0)]); - sum00 = bfdotadd(sum00, n[s + H4(0 + 1)], m[s + H4(0 + 1)]); + /* + * Process the entire segment at once, writing back the + * results only after we've consumed all of the inputs. + * + * Key to indices by column: + * i j i k j k + */ + sum00 = a[s + H4(0 + 0)]; + sum00 = bfdotadd_ebf(sum00, n[s + H4(0 + 0)], m[s + H4(0 + 0)], &fpst, &fpst_odd); + sum00 = bfdotadd_ebf(sum00, n[s + H4(0 + 1)], m[s + H4(0 + 1)], &fpst, &fpst_odd); - sum01 = a[s + H4(0 + 1)]; - sum01 = bfdotadd(sum01, n[s + H4(0 + 0)], m[s + H4(2 + 0)]); - sum01 = bfdotadd(sum01, n[s + H4(0 + 1)], m[s + H4(2 + 1)]); + sum01 = a[s + H4(0 + 1)]; + sum01 = bfdotadd_ebf(sum01, n[s + H4(0 + 0)], m[s + H4(2 + 0)], &fpst, &fpst_odd); + sum01 = bfdotadd_ebf(sum01, n[s + H4(0 + 1)], m[s + H4(2 + 1)], &fpst, &fpst_odd); - sum10 = a[s + H4(2 + 0)]; - sum10 = bfdotadd(sum10, n[s + H4(2 + 0)], m[s + H4(0 + 0)]); - sum10 = bfdotadd(sum10, n[s + H4(2 + 1)], m[s + H4(0 + 1)]); + sum10 = a[s + H4(2 + 0)]; + sum10 = bfdotadd_ebf(sum10, n[s + H4(2 + 0)], m[s + H4(0 + 0)], &fpst, &fpst_odd); + sum10 = bfdotadd_ebf(sum10, n[s + H4(2 + 1)], m[s + H4(0 + 1)], &fpst, &fpst_odd); - sum11 = a[s + H4(2 + 1)]; - sum11 = bfdotadd(sum11, n[s + H4(2 + 0)], m[s + H4(2 + 0)]); - sum11 = bfdotadd(sum11, n[s + H4(2 + 1)], m[s + H4(2 + 1)]); + sum11 = a[s + H4(2 + 1)]; + sum11 = bfdotadd_ebf(sum11, n[s + H4(2 + 0)], m[s + H4(2 + 0)], &fpst, &fpst_odd); + sum11 = bfdotadd_ebf(sum11, n[s + H4(2 + 1)], m[s + H4(2 + 1)], &fpst, &fpst_odd); - d[s + H4(0 + 0)] = sum00; - d[s + H4(0 + 1)] = sum01; - d[s + H4(2 + 0)] = sum10; - d[s + H4(2 + 1)] = sum11; + d[s + H4(0 + 0)] = sum00; + d[s + H4(0 + 1)] = sum01; + d[s + H4(2 + 0)] = sum10; + d[s + H4(2 + 1)] = sum11; + } + } else { + for (s = 0; s < opr_sz / 4; s += 4) { + float32 sum00, sum01, sum10, sum11; + + /* + * Process the entire segment at once, writing back the + * results only after we've consumed all of the inputs. + * + * Key to indices by column: + * i j i k j k + */ + sum00 = a[s + H4(0 + 0)]; + sum00 = bfdotadd(sum00, n[s + H4(0 + 0)], m[s + H4(0 + 0)], &fpst); + sum00 = bfdotadd(sum00, n[s + H4(0 + 1)], m[s + H4(0 + 1)], &fpst); + + sum01 = a[s + H4(0 + 1)]; + sum01 = bfdotadd(sum01, n[s + H4(0 + 0)], m[s + H4(2 + 0)], &fpst); + sum01 = bfdotadd(sum01, n[s + H4(0 + 1)], m[s + H4(2 + 1)], &fpst); + + sum10 = a[s + H4(2 + 0)]; + sum10 = bfdotadd(sum10, n[s + H4(2 + 0)], m[s + H4(0 + 0)], &fpst); + sum10 = bfdotadd(sum10, n[s + H4(2 + 1)], m[s + H4(0 + 1)], &fpst); + + sum11 = a[s + H4(2 + 1)]; + sum11 = bfdotadd(sum11, n[s + H4(2 + 0)], m[s + H4(2 + 0)], &fpst); + sum11 = bfdotadd(sum11, n[s + H4(2 + 1)], m[s + H4(2 + 1)], &fpst); + + d[s + H4(0 + 0)] = sum00; + d[s + H4(0 + 1)] = sum01; + d[s + H4(2 + 0)] = sum10; + d[s + H4(2 + 1)] = sum11; + } } clear_tail(d, opr_sz, simd_maxsz(desc)); }