{"id":2222987,"url":"http://patchwork.ozlabs.org/api/patches/2222987/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/ad3qTveCIFUtTGLg@tucnak/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/projects/17/?format=json","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":"","list_archive_url":null,"date":"2026-04-14T07:18:38","name":"bitintlower: Handle BIT_FIELD_REF load [PR124826]","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"581c9ca9af23982cbdfca8226d0b5cd19bcb77f0","submitter":{"id":671,"url":"http://patchwork.ozlabs.org/api/people/671/?format=json","name":"Jakub Jelinek","email":"jakub@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/ad3qTveCIFUtTGLg@tucnak/mbox/","series":[{"id":499791,"url":"http://patchwork.ozlabs.org/api/series/499791/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=499791","date":"2026-04-14T07:18:38","name":"bitintlower: Handle BIT_FIELD_REF load [PR124826]","version":1,"mbox":"http://patchwork.ozlabs.org/series/499791/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2222987/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2222987/checks/","tags":{},"related":[],"headers":{"Return-Path":"","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 (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=e9zn32ox;\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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charset=us-ascii","Content-Disposition":"inline","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Reply-To":"Jakub Jelinek ","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org"},"content":"Hi!\n\nThe following testcase ends up with a BIT_FIELD_REF from a VECTOR_TYPE union\nmember to _BitInt(256). gimple-lower-bitint.cc already contains code to\nhandle BIT_FIELD_REFs with SSA_NAME first operand to BITINT_TYPE (for\nconstant index limb access by adjusting the BIT_FIELD_REF to use different\nbitsize and index, for variable index (huge _BitInt with limbs accessed in a loop)\nby forcing the SSA_NAME into memory), but that doesn't trigger here, because\ngimple_assign_load_p predicate is true on it and so it is handled as load\nand not BIT_FIELD_REF. Anyway, the problem is that we end up with\n_7 = VIEW_CONVERT_EXPR(BIT_FIELD_REF )[_2];\nwhich tree-cfg.cc verifier doesn't like because BIT_FIELD_REF is not\ntoplevel reference in there. The following patch just strips the\nBIT_FIELD_REF away if it has zero bit offset, that is the only case I've\nmanaged to reproduce, and in that case we are still later on using VCE to\nconvert to array and using ARRAY_REF on that. If offset could be non-zero\nbut multiple of BITS_PER_UNIT, another approach would be to replace\nBIT_FIELD_REF with a MEM_REF. Anyway, as I haven't managed to reproduce\nit with anything but 0, the following patch is enough.\n\nBootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?\n\n2026-04-14 Jakub Jelinek \n\n\tPR tree-optimization/124826\n\t* gimple-lower-bitint.cc (bitint_large_huge::handle_load): Look through\n\tBIT_FIELD_REF with zero bit offset.\n\n\t* gcc.dg/bitint-128.c: New test.\n\n\n\tJakub","diff":"--- gcc/gimple-lower-bitint.cc.jj\t2026-03-27 10:17:14.164330250 +0100\n+++ gcc/gimple-lower-bitint.cc\t2026-04-13 18:41:02.149286578 +0200\n@@ -1985,6 +1985,10 @@ bitint_large_huge::handle_load (gimple *\n edge eh_edge = NULL;\n gimple *g;\n \n+ if (TREE_CODE (rhs1) == BIT_FIELD_REF\n+ && integer_zerop (TREE_OPERAND (rhs1, 2)))\n+ rhs1 = TREE_OPERAND (rhs1, 0);\n+\n if (eh)\n {\n edge_iterator ei;\n--- gcc/testsuite/gcc.dg/bitint-128.c.jj\t2026-04-13 18:49:40.292517820 +0200\n+++ gcc/testsuite/gcc.dg/bitint-128.c\t2026-04-13 18:49:04.001131057 +0200\n@@ -0,0 +1,27 @@\n+/* PR tree-optimization/124826 */\n+/* { dg-do compile { target bitint } } */\n+/* { dg-options \"-O2\" } */\n+\n+typedef float V __attribute__((vector_size (16 * sizeof (float))));\n+\n+union {\n+#if __BITINT_MAXWIDTH__ >= 256\n+ _BitInt(256) b;\n+#endif\n+ V v;\n+} u;\n+\n+void\n+foo (int c)\n+{\n+ u.v -= c ? 0.f : 1.f;\n+#if __BITINT_MAXWIDTH__ >= 256\n+ u.b *= c;\n+#endif\n+}\n+\n+int\n+main ()\n+{\n+ foo (2);\n+}\n","prefixes":[]}