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GET /api/patches/2225424/?format=api
{ "id": 2225424, "url": "http://patchwork.ozlabs.org/api/patches/2225424/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/patch/aeboBtP2T1w1r05A@cowardly-lion.the-meissners.org/", "project": { "id": 17, "url": "http://patchwork.ozlabs.org/api/projects/17/?format=api", "name": "GNU Compiler Collection", "link_name": "gcc", "list_id": "gcc-patches.gcc.gnu.org", "list_email": "gcc-patches@gcc.gnu.org", "web_url": null, "scm_url": null, "webscm_url": null, "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<aeboBtP2T1w1r05A@cowardly-lion.the-meissners.org>", "list_archive_url": null, "date": "2026-04-21T02:59:18", "name": "GCC 17.0 PowerPC patches V6 [PATCH 2/5]: Add saturate subtract support", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "2b00d63501d60a21d3bb85ecb890032b82aa18a8", "submitter": { "id": 73991, "url": "http://patchwork.ozlabs.org/api/people/73991/?format=api", "name": "Michael Meissner", "email": "meissner@linux.ibm.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/gcc/patch/aeboBtP2T1w1r05A@cowardly-lion.the-meissners.org/mbox/", "series": [ { "id": 500716, "url": "http://patchwork.ozlabs.org/api/series/500716/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/list/?series=500716", "date": "2026-04-21T02:59:18", "name": "GCC 17.0 PowerPC patches V6 [PATCH 2/5]: Add saturate subtract support", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/500716/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2225424/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2225424/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "gcc-patches@gcc.gnu.org" ], "Delivered-To": [ "patchwork-incoming@legolas.ozlabs.org", "gcc-patches@gcc.gnu.org" ], "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256\n header.s=pp1 header.b=XiJTCwpT;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=38.145.34.32; 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a=rsa-sha256; d=sourceware.org; s=key; t=1776740365; cv=none;\n b=nQHFP8gFIr0T3gOks43grcedz7fDL8R8O3wwwkAzrfs8eQgWae8Sb7MYLxrH83k0t0xYBHVnDUzmHxPU3ZJXJkSWWJ0OraIKlX4ZbnxEk8b6L9IHfi8iN0Zig+SrmQqXDnYcwAAuEuL/54HnLUlLsfk0zunb/MJ4o5SzWVkr8RQ=", "ARC-Message-Signature": "i=1; a=rsa-sha256; d=sourceware.org; s=key;\n t=1776740365; c=relaxed/simple;\n bh=OxpyaUyTe612FqUZ3vvl+BHSddoFxSa70qea21N3WvE=;\n h=DKIM-Signature:Date:From:To:Subject:Message-ID:MIME-Version;\n b=YC1hgBjB7jlQU4lZxwsiqJLurnCPoet9efF60jv432ARBkkTxXmRZ5z2haONDApGF8iScngQQ0NtMx84mwVh200uXaViT0UhTjIARg+pzR64uyp3cH7EZ14FK09X+stUVnQzUno7q59DOndptOQ4JrFTxqhJ8Z293PYyIf0+pUA=", "ARC-Authentication-Results": "i=1; server2.sourceware.org", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=\n content-type:date:from:in-reply-to:message-id:mime-version\n :references:subject:to; s=pp1; bh=2gjqnOp1Ui0d44hxf/xjb903E8rDxW\n oFyaybi9XrGaM=; b=XiJTCwpTT/FNTv0yrSA05Gw0UvGiESyXB26kcNEIggE8TQ\n iL52Wl2zQ6kZGn0UovWmtHoZOzAgWZWcZ7lhENwE+/0XzQEpVhDFTWF8KnGtG+Su\n b4vZCMIX7Z2HM7IVYCMlKjOIJ34ZWZG2StysurGSZJxCplGsx0hANDFrL36mSp7o\n FGVgb/ICLfXPRo92OsB51fUWkXwujrOtWkP9RJ3AkSeVC9gyBXyXGyZeO86PWrvd\n bx2JAXfbiJyAf0aymMtw+NoxQgcRnrs8oa7GGo4WghaGzbtKzoQKVmqqxRrYLyot\n mSzhBZDNPLoxtP4CmI3sGT6EKMoJr7PUwWtGNI2A==", "Date": "Mon, 20 Apr 2026 22:59:18 -0400", "From": "Michael Meissner <meissner@linux.ibm.com>", "To": "Michael Meissner <meissner@linux.ibm.com>, gcc-patches@gcc.gnu.org,\n Segher Boessenkool <segher@kernel.crashing.org>,\n jeevitha <jeevitha@linux.ibm.com>,\n Surya Kumari Jangala <jskumari@linux.ibm.com>,\n Kishan Parmar <kishan@linux.ibm.com>,\n Avinash Jayakar <avinashd@linux.ibm.com>,\n Ayappan Perumal <ayappap2@in.ibm.com>,\n Juergen Christ <jchrist@linux.ibm.com>", "Subject": "GCC 17.0 PowerPC patches V6 [PATCH 2/5]: Add saturate subtract\n support", "Message-ID": "<aeboBtP2T1w1r05A@cowardly-lion.the-meissners.org>", "Mail-Followup-To": "Michael Meissner <meissner@linux.ibm.com>,\n gcc-patches@gcc.gnu.org,\n Segher Boessenkool <segher@kernel.crashing.org>,\n jeevitha <jeevitha@linux.ibm.com>,\n Surya Kumari Jangala <jskumari@linux.ibm.com>,\n Kishan Parmar <kishan@linux.ibm.com>,\n Avinash Jayakar <avinashd@linux.ibm.com>,\n Ayappan Perumal <ayappap2@in.ibm.com>,\n Juergen Christ <jchrist@linux.ibm.com>", "References": "<aebT1QQbPenBOFeH@cowardly-lion.the-meissners.org>\n <aebmUidtQeOwvHIY@cowardly-lion.the-meissners.org>", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=us-ascii", "Content-Disposition": "inline", "In-Reply-To": "<aebmUidtQeOwvHIY@cowardly-lion.the-meissners.org>", "X-TM-AS-GCONF": "00", "X-Proofpoint-Spam-Details-Enc": "AW1haW4tMjYwNDIxMDAyNiBTYWx0ZWRfX+dUpl++07saL\n 3eXflQGditASMhHlGFZm0Us1VulRfH/Dc1yEjH8wjOvSSd8DodEq3YKfUiRB24sH+7qm6txC7Bn\n wbbzaqrGNyreDv862VP6SWITvgvjdul3sECOPJXpTOfEwL+VrgejxW9z+rGSPVy07JcGyyT6Au/\n w095LQLHkLKPLqL2dYllfAi1rkPlGPQDwk6A4vF48LQdjgX6YhxnDmxH0NSPBnMuI85KjhTBDWF\n 8QArC8k+zzPch17s+BpK1ksePbj9p33GEB9hQnPWzkClmyF/5PUtsogEzNpyhBmQhojKG+4dOAx\n R+LfRlZKegBvPM27LTN8Ct7jbunV4jcQSx8AqThxUtcPOocdVRz33yqOcBrvzRrr85MPlmIGijG\n jqGgTCrmNDG8EZaOxLwOPbpWvZk4kNwx/DuXzk4Tb/FLrxByIJ8nia/3RfQhL2JAa7rl2m9lKVG\n 3ISbBObA8pVpSDN0OAA==", "X-Proofpoint-GUID": "hwN6N8lYHs0toA-gg0IC3QPBxeC5dtYl", "X-Authority-Analysis": "v=2.4 cv=SOJykuvH c=1 sm=1 tr=0 ts=69e6e80c cx=c_pps\n a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17\n a=kj9zAlcOel0A:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22\n a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=mDV3o1hIAAAA:8\n a=VnNF1IyMAAAA:8 a=H_X61Btrdrbtd-VXSpwA:9 a=CjuIK1q_8ugA:10", "X-Proofpoint-ORIG-GUID": "hwN6N8lYHs0toA-gg0IC3QPBxeC5dtYl", "X-Proofpoint-Virus-Version": "vendor=baseguard\n engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49\n definitions=2026-04-20_05,2026-04-20_02,2025-10-01_01", "X-Proofpoint-Spam-Details": "rule=outbound_notspam policy=outbound score=0\n malwarescore=0 spamscore=0 priorityscore=1501 lowpriorityscore=0\n clxscore=1015 phishscore=0 suspectscore=0 adultscore=0 impostorscore=0\n bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound\n adjust=0 reason=mlx scancount=1 engine=8.22.0-2604070000\n definitions=main-2604210026", "X-BeenThere": "gcc-patches@gcc.gnu.org", "X-Mailman-Version": "2.1.30", "Precedence": "list", "List-Id": "Gcc-patches mailing list <gcc-patches.gcc.gnu.org>", "List-Unsubscribe": "<https://gcc.gnu.org/mailman/options/gcc-patches>,\n <mailto:gcc-patches-request@gcc.gnu.org?subject=unsubscribe>", "List-Archive": "<https://gcc.gnu.org/pipermail/gcc-patches/>", "List-Post": "<mailto:gcc-patches@gcc.gnu.org>", "List-Help": "<mailto:gcc-patches-request@gcc.gnu.org?subject=help>", "List-Subscribe": "<https://gcc.gnu.org/mailman/listinfo/gcc-patches>,\n <mailto:gcc-patches-request@gcc.gnu.org?subject=subscribe>", "Errors-To": "gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org" }, "content": "This patch adds support for saturating subtract instructions that might be added\nto a future PowerPC. I think I had originally submitted patches that added a\nnew built-in function to generate the subfus and subdus instructions. Segher\nsuggested that instead of generating a built-in function, that I should just\nhaving GCC automatically recognize cases where a saturating subtract could be\ngenerated. This patch generates the saturating subtract instructions in the\nappropriate context.\n\nThis patch needs the -mcpu=future patch posted on April 8th, 2026:\n\n * https://gcc.gnu.org/pipermail/gcc-patches/2026-April/712532.html\n\nI have built bootstrap little endian compilers on power10 systems, and\nbig endian compiler on power9 systems. There were no regression in the\ntests. Can I add the patches to the GCC trunk after the -mcpu=future\npatch is applied and GCC 17 has opened up?\n\ngcc/\n\n2026-04-20 Michael Meissner <meissner@linux.ibm.com>\n\n\t* config/rs6000/rs6000.md (gtu_geu): New code iterator.\n\t(subfus<mode>3_<code>): New insns.\n\ngcc/testsuite/\n\n2026-04-16 Michael Meissner <meissner@linux.ibm.com>\n\n\t* gcc.target/powerpc/saturate-subtract-1.c: New test.\n\t* gcc.target/powerpc/saturate-subtract-2.c: Likewise.\n\t* lib/target-supports.exp (check_effective_target_powerpc_future_ok):\n\tNew target test.\n---\n gcc/config/rs6000/rs6000.md | 14 +++++++\n .../gcc.target/powerpc/saturate-subtract-1.c | 39 ++++++++++++++++++\n .../gcc.target/powerpc/saturate-subtract-2.c | 40 +++++++++++++++++++\n gcc/testsuite/lib/target-supports.exp | 13 ++++++\n 4 files changed, 106 insertions(+)\n create mode 100644 gcc/testsuite/gcc.target/powerpc/saturate-subtract-1.c\n create mode 100644 gcc/testsuite/gcc.target/powerpc/saturate-subtract-2.c", "diff": "diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md\nindex 57a239791ee..199a95b84c4 100644\n--- a/gcc/config/rs6000/rs6000.md\n+++ b/gcc/config/rs6000/rs6000.md\n@@ -2397,6 +2397,20 @@ (define_insn_and_split \"*subfsi3_carry_in_xx_64\"\n \"\"\n )\n \n+;; Saturating subtract\n+(define_code_iterator gtu_geu [gtu geu])\n+\n+(define_insn \"*subfus<mode>3_<code>\"\n+ [(set (match_operand:GPR 0 \"gpc_reg_operand\" \"=r\")\n+\t(if_then_else:GPR (gtu_geu (match_operand:GPR 1 \"gpc_reg_operand\" \"r\")\n+\t\t\t\t (match_operand:GPR 2 \"gpc_reg_operand\" \"r\"))\n+\t\t\t (minus:GPR (match_dup 1)\n+\t\t\t\t (match_dup 2))\n+\t\t\t (const_int 0)))]\n+ \"TARGET_FUTURE\"\n+ \"sub<wd>us %0,%1,%2\"\n+ [(set_attr \"type\" \"add\")])\n+\n (define_insn \"@neg<mode>2\"\n [(set (match_operand:GPR 0 \"gpc_reg_operand\" \"=r\")\n \t(neg:GPR (match_operand:GPR 1 \"gpc_reg_operand\" \"r\")))]\ndiff --git a/gcc/testsuite/gcc.target/powerpc/saturate-subtract-1.c b/gcc/testsuite/gcc.target/powerpc/saturate-subtract-1.c\nnew file mode 100644\nindex 00000000000..c32a70a5e89\n--- /dev/null\n+++ b/gcc/testsuite/gcc.target/powerpc/saturate-subtract-1.c\n@@ -0,0 +1,39 @@\n+/* { dg-do compile } */\n+/* { dg-options \"-mdejagnu-cpu=future -O2\" } */\n+/* { dg-require-effective-target powerpc_future_ok } */\n+\n+/* Check that saturating subtract (subfus) is generated. Check that all\n+ combinations of >, >=, <, and <= are optimized. */\n+\n+#ifndef TYPE\n+#define TYPE\tunsigned int\n+#endif\n+\n+void\n+saturated_subtract_gt (TYPE a, TYPE b, TYPE *p)\n+{\n+ *p = (a > b) ? a - b : 0;\n+}\n+\n+void\n+saturated_subtract_ge (TYPE a, TYPE b, TYPE *p)\n+{\n+ *p = (a >= b) ? a - b : 0;\n+}\n+\n+void\n+saturated_subtract_lt (TYPE a, TYPE b, TYPE *p)\n+{\n+ *p = (a < b) ? 0 : a - b;\n+}\n+\n+void\n+saturated_subtract_le (TYPE a, TYPE b, TYPE *p)\n+{\n+ *p = (a <= b) ? 0 : a - b;\n+}\n+\n+/* { dg-final { scan-assembler-times {\\msubwus\\M} 4 } } */\n+/* { dg-final { scan-assembler-not {\\mcmplw\\M} } } */\n+/* { dg-final { scan-assembler-not {\\misel\\M} } } */\n+/* { dg-final { scan-assembler-not {\\msubf\\M} } } */\ndiff --git a/gcc/testsuite/gcc.target/powerpc/saturate-subtract-2.c b/gcc/testsuite/gcc.target/powerpc/saturate-subtract-2.c\nnew file mode 100644\nindex 00000000000..482d7384c17\n--- /dev/null\n+++ b/gcc/testsuite/gcc.target/powerpc/saturate-subtract-2.c\n@@ -0,0 +1,40 @@\n+/* { dg-do compile } */\n+/* { dg-require-effective-target powerpc_future_ok } */\n+/* { dg-require-effective-target lp64 } */\n+/* { dg-options \"-mdejagnu-cpu=future -O2\" } */\n+\n+/* Check that saturating subtract (subfus) is generated. Check that all\n+ combinations of >, >=, <, and <= are optimized. */\n+\n+#ifndef TYPE\n+#define TYPE\tunsigned long long\n+#endif\n+\n+void\n+saturated_subtract_gt (TYPE a, TYPE b, TYPE *p)\n+{\n+ *p = (a > b) ? a - b : 0;\n+}\n+\n+void\n+saturated_subtract_ge (TYPE a, TYPE b, TYPE *p)\n+{\n+ *p = (a >= b) ? a - b : 0;\n+}\n+\n+void\n+saturated_subtract_lt (TYPE a, TYPE b, TYPE *p)\n+{\n+ *p = (a < b) ? 0 : a - b;\n+}\n+\n+void\n+saturated_subtract_le (TYPE a, TYPE b, TYPE *p)\n+{\n+ *p = (a <= b) ? 0 : a - b;\n+}\n+\n+/* { dg-final { scan-assembler-times {\\msubdus\\M} 4 } } */\n+/* { dg-final { scan-assembler-not {\\mcmpld\\M} } } */\n+/* { dg-final { scan-assembler-not {\\misel\\M} } } */\n+/* { dg-final { scan-assembler-not {\\msubf\\M} } } */\ndiff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp\nindex 1b9e0bf8f49..0149f6f5c13 100644\n--- a/gcc/testsuite/lib/target-supports.exp\n+++ b/gcc/testsuite/lib/target-supports.exp\n@@ -8194,6 +8194,19 @@ proc check_htm_hw_available { } {\n \t}\n }]\n }\n+\n+# Return 1 if this is a PowerPC target supporting -mcpu=future\n+\n+proc check_effective_target_powerpc_future_ok { } {\n+ return [check_no_compiler_messages powerpc_future_ok object {\n+\tunsigned long a, b, c;\n+\tint main (void) {\n+\t asm (\"subdus %0,%1,%2\" : \"=r\" (a) : \"r\" (b), \"r\" (c));\n+\t return 0;\n+\t}\n+ } \"-mcpu=future\"]\n+}\n+\n # Return 1 if this is a PowerPC target supporting -mcpu=cell.\n \n proc check_effective_target_powerpc_ppu_ok { } {\n", "prefixes": [] }