[{"id":3678962,"web_url":"http://patchwork.ozlabs.org/comment/3678962/","msgid":"<87ik9osclf.fsf@googlemail.com>","list_archive_url":null,"date":"2026-04-18T11:59:56","subject":"Re: [PATCH 1/7] aarch64: Add ZTO_REGNUM use to movt","submitter":{"id":4363,"url":"http://patchwork.ozlabs.org/api/people/4363/","name":"Richard Sandiford","email":"rdsandiford@googlemail.com"},"content":"Alice Carlotti writes:\n> Also replace unspec_volatile with plain unspec - there no need to\n> prevent dead code elimination if the dependencies are correct.\n>\n> ---\n>\n> If the index is 0, then movt is a destructive instruction, so it should be\n> possible to remove the dependency in that case. However, that would be a more\n> disruptive chane, so we can leave it till stage 1.\n>\n>\n> gcc/ChangeLog:\n>\n> \t* config/aarch64/aarch64-sme.md (aarch64_sme_write_zt): Add\n> \tZTO_REGNUM use and make unspec non-volatile.\n>\n> gcc/testsuite/ChangeLog:\n>\n> \t* gcc.target/aarch64/sme/zt0_state_8.c: New test.\n\nOK, thanks.\n\nRichard\n\n> diff --git a/gcc/config/aarch64/aarch64-sme.md b/gcc/config/aarch64/aarch64-sme.md\n> index f24e91997fd640f82c11353dd196fe334daec630..d5564e57bdf130bb51daf5c52be5a743ab32064d 100644\n> --- a/gcc/config/aarch64/aarch64-sme.md\n> +++ b/gcc/config/aarch64/aarch64-sme.md\n> @@ -1067,8 +1067,9 @@\n> ;; __arm_streaming __arm_out (\"zt0\");\n> (define_insn \"@aarch64_sme_write_zt\"\n> [(set (reg:V8DI ZT0_REGNUM)\n> -\t(unspec_volatile:V8DI\n> -\t [(match_operand:SVE_FULL 0 \"register_operand\" \"w\")\n> +\t(unspec:V8DI\n> +\t [(reg:V8DI ZT0_REGNUM)\n> +\t (match_operand:SVE_FULL 0 \"register_operand\" \"w\")\n> \t (match_operand:DI 1 \"const_int_operand\")]\n> \t UNSPEC_SME_WRITE))]\n> \"TARGET_SME_LUTv2 && TARGET_STREAMING\"\n> diff --git a/gcc/testsuite/gcc.target/aarch64/sme/zt0_state_8.c b/gcc/testsuite/gcc.target/aarch64/sme/zt0_state_8.c\n> new file mode 100644\n> index 0000000000000000000000000000000000000000..8eb3d424f539d8a645a9889f465ac9013048b5f5\n> --- /dev/null\n> +++ b/gcc/testsuite/gcc.target/aarch64/sme/zt0_state_8.c\n> @@ -0,0 +1,14 @@\n> +// { dg-options \"-O3 -fomit-frame-pointer -fno-optimize-sibling-calls\" }\n> +\n> +#include \n> +\n> +#pragma GCC target \"+sme2+sme-lutv2\"\n> +\n> +__arm_streaming __arm_inout(\"zt0\")\n> +void foo(svfloat32_t z)\n> +{\n> + svzero_zt (0);\n> + svwrite_lane_zt_f32 (0, z, 1);\n> +}\n> +\n> +// { dg-final { scan-assembler \"zero\" } }","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 (2048-bit key;\n unprotected) header.d=googlemail.com header.i=@googlemail.com\n header.a=rsa-sha256 header.s=20251104 header.b=gzPoaApj;\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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