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GET /api/1.2/patches/2234397/?format=api
{ "id": 2234397, "url": "http://patchwork.ozlabs.org/api/1.2/patches/2234397/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260507160959.449170-2-richard.henderson@linaro.org/", "project": { "id": 14, "url": "http://patchwork.ozlabs.org/api/1.2/projects/14/?format=api", "name": "QEMU Development", "link_name": "qemu-devel", "list_id": "qemu-devel.nongnu.org", "list_email": "qemu-devel@nongnu.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260507160959.449170-2-richard.henderson@linaro.org>", "list_archive_url": null, "date": "2026-05-07T16:09:49", "name": "[v3,01/11] fpu: Reorganize partsN(muladd)", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "b40f8973e3854ae649e6bec67db8194dc9f0d084", "submitter": { "id": 72104, "url": "http://patchwork.ozlabs.org/api/1.2/people/72104/?format=api", "name": "Richard Henderson", "email": "richard.henderson@linaro.org" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260507160959.449170-2-richard.henderson@linaro.org/mbox/", "series": [ { "id": 503213, "url": "http://patchwork.ozlabs.org/api/1.2/series/503213/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=503213", "date": "2026-05-07T16:09:49", "name": "fpu: Export some internals for targets", "version": 3, "mbox": "http://patchwork.ozlabs.org/series/503213/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2234397/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2234397/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n 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"X-Spam_bar": "--", "X-Spam_report": "(-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001,\n 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": "qemu development <qemu-devel.nongnu.org>", "List-Unsubscribe": "<https://lists.nongnu.org/mailman/options/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>", "List-Archive": "<https://lists.nongnu.org/archive/html/qemu-devel>", "List-Post": "<mailto:qemu-devel@nongnu.org>", "List-Help": "<mailto:qemu-devel-request@nongnu.org?subject=help>", "List-Subscribe": "<https://lists.nongnu.org/mailman/listinfo/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=subscribe>", "Errors-To": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org", "Sender": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org" }, "content": "Check the likely case of normal product and normal or\nzero addend first; shift NaN and infinity detection down;\nend with zero product + addend.\n\nSigned-off-by: Richard Henderson <richard.henderson@linaro.org>\n---\n fpu/softfloat-parts.c.inc | 155 +++++++++++++++++---------------------\n 1 file changed, 70 insertions(+), 85 deletions(-)", "diff": "diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc\nindex 3a9c2748cd..3d2606c07c 100644\n--- a/fpu/softfloat-parts.c.inc\n+++ b/fpu/softfloat-parts.c.inc\n@@ -681,11 +681,47 @@ static FloatPartsN *partsN(muladd)(FloatPartsN *a, FloatPartsN *b,\n FloatPartsN *c,\n int flags, float_status *s)\n {\n- int ab_mask, abc_mask;\n- FloatPartsW p_widen, c_widen;\n+ int ab_mask = float_cmask(a->cls) | float_cmask(b->cls);\n+ int c_mask = float_cmask(c->cls);\n+ int abc_mask = ab_mask | c_mask;\n+ bool c_sign = c->sign ^ !!(flags & float_muladd_negate_c);\n+ bool p_sign = a->sign ^ b->sign ^ !!(flags & float_muladd_negate_product);\n \n- ab_mask = float_cmask(a->cls) | float_cmask(b->cls);\n- abc_mask = float_cmask(c->cls) | ab_mask;\n+ /*\n+ * The \"likely\" case is A and B normal, so that the product is normal,\n+ * and C normal or zero so that the result is normal.\n+ */\n+ int likely_mask = ab_mask | (c_mask & ~float_cmask_zero);\n+ if (likely(cmask_is_only_normals(likely_mask))) {\n+ record_denormals_used(abc_mask, s);\n+\n+ /* Perform the multiplication step. */\n+ FloatPartsW p_widen = { .sign = p_sign, .exp = a->exp + b->exp + 1 };\n+ fracN(mulw)(&p_widen, a, b);\n+ if (!(p_widen.frac_hi & DECOMPOSED_IMPLICIT_BIT)) {\n+ fracW(add)(&p_widen, &p_widen, &p_widen);\n+ p_widen.exp -= 1;\n+ }\n+\n+ /* Perform the addition step. */\n+ if (!(c_mask & float_cmask_zero)) {\n+ /* Zero-extend C to less significant bits. */\n+ FloatPartsW c_widen = { .sign = c_sign, .exp = c->exp };\n+ fracN(widen)(&c_widen, c);\n+\n+ if (p_sign == c_sign) {\n+ partsW(add_normal)(&p_widen, &c_widen);\n+ } else if (!partsW(sub_normal)(&p_widen, &c_widen)) {\n+ goto return_sub_zero;\n+ }\n+ }\n+\n+ /* Narrow with sticky bit, for proper rounding later. */\n+ fracN(truncjam)(a, &p_widen);\n+ a->sign = p_widen.sign;\n+ a->exp = p_widen.exp;\n+ return a;\n+ }\n \n /*\n * It is implementation-defined whether the cases of (0,inf,qnan)\n@@ -698,97 +734,46 @@ static FloatPartsN *partsN(muladd)(FloatPartsN *a, FloatPartsN *b,\n return a;\n }\n \n- if (flags & float_muladd_negate_c) {\n- c->sign ^= 1;\n+ if (unlikely(ab_mask == float_cmask_infzero)) {\n+ /* Inf * Zero == NaN */\n+ float_raise(float_flag_invalid | float_flag_invalid_imz, s);\n+ goto d_nan;\n }\n \n- /* Compute the sign of the product into A. */\n- a->sign ^= b->sign;\n- if (flags & float_muladd_negate_product) {\n- a->sign ^= 1;\n- }\n-\n- if (unlikely(!cmask_is_only_normals(ab_mask))) {\n- if (unlikely(ab_mask == float_cmask_infzero)) {\n- float_raise(float_flag_invalid | float_flag_invalid_imz, s);\n+ if (unlikely(ab_mask & float_cmask_inf)) {\n+ if ((c_mask & float_cmask_inf) && p_sign != c_sign) {\n+ /* Inf - Inf == NaN */\n+ float_raise(float_flag_invalid | float_flag_invalid_isi, s);\n goto d_nan;\n }\n-\n- if (ab_mask & float_cmask_inf) {\n- if (c->cls == float_class_inf && a->sign != c->sign) {\n- float_raise(float_flag_invalid | float_flag_invalid_isi, s);\n- goto d_nan;\n- }\n- goto return_inf;\n- }\n-\n- g_assert(ab_mask & float_cmask_zero);\n- if (is_anynorm(c->cls)) {\n- *a = *c;\n- goto finish_sign;\n- }\n- if (c->cls == float_class_zero) {\n- if (flags & float_muladd_suppress_add_product_zero) {\n- a->sign = c->sign;\n- } else if (a->sign != c->sign) {\n- goto return_sub_zero;\n- }\n- goto return_zero;\n- }\n- g_assert(c->cls == float_class_inf);\n+ /* Inf + C == Inf */\n+ record_denormals_used(abc_mask, s);\n+ a->sign = p_sign;\n+ a->cls = float_class_inf;\n+ return a;\n }\n-\n- if (unlikely(c->cls == float_class_inf)) {\n- a->sign = c->sign;\n- goto return_inf;\n- }\n-\n- /* Perform the multiplication step. */\n- p_widen.sign = a->sign;\n- p_widen.exp = a->exp + b->exp + 1;\n- fracN(mulw)(&p_widen, a, b);\n- if (!(p_widen.frac_hi & DECOMPOSED_IMPLICIT_BIT)) {\n- fracW(add)(&p_widen, &p_widen, &p_widen);\n- p_widen.exp -= 1;\n- }\n-\n- /* Perform the addition step. */\n- if (c->cls != float_class_zero) {\n- /* Zero-extend C to less significant bits. */\n- fracN(widen)(&c_widen, c);\n- c_widen.exp = c->exp;\n-\n- if (a->sign == c->sign) {\n- partsW(add_normal)(&p_widen, &c_widen);\n- } else if (!partsW(sub_normal)(&p_widen, &c_widen)) {\n- goto return_sub_zero;\n- }\n- }\n-\n- /* Narrow with sticky bit, for proper rounding later. */\n- fracN(truncjam)(a, &p_widen);\n- a->sign = p_widen.sign;\n- a->exp = p_widen.exp;\n-\n- finish_sign:\n- /*\n- * All result types except for \"return the default NaN\n- * because this is an Invalid Operation\" go through here;\n- * this matches the set of cases where we consumed a\n- * denormal input.\n- */\n record_denormals_used(abc_mask, s);\n- return a;\n+\n+ /* Only remaining case is zero product. */\n+ assert(ab_mask & float_cmask_zero);\n+\n+ /*\n+ * 0 + C == C,\n+ * except for 0 - 0, which needs special rounding,\n+ * except for when we want to suppress this addition step.\n+ */\n+ if (!(c_mask & float_cmask_zero)\n+ || p_sign == c_sign\n+ || (flags & float_muladd_suppress_add_product_zero)) {\n+ c->sign = c_sign;\n+ return c;\n+ }\n \n return_sub_zero:\n+ /* 0 - 0 == -0 for round_down, +0 otherwise. */\n a->sign = s->float_rounding_mode == float_round_down;\n- return_zero:\n a->cls = float_class_zero;\n- goto finish_sign;\n-\n- return_inf:\n- a->cls = float_class_inf;\n- goto finish_sign;\n+ return a;\n \n d_nan:\n *a = partsN(default_nan)(s);\n", "prefixes": [ "v3", "01/11" ] }