[{"id":1769723,"web_url":"http://patchwork.ozlabs.org/comment/1769723/","msgid":"","list_archive_url":null,"date":"2017-09-17T15:44:15","subject":"Re: [PATCH] PR target/82166: Update preferred stack boundary for\n\tleaf functions","submitter":{"id":808,"url":"http://patchwork.ozlabs.org/api/people/808/","name":"Uros Bizjak","email":"ubizjak@gmail.com"},"content":"On Mon, Sep 11, 2017 at 3:57 AM, H.J. Lu wrote:\n> preferred_stack_boundary may not be the minimum stack alignment. For\n> leaf functions without TLS access, max_used_stack_slot_alignment may be\n> smaller. We should update preferred_stack_boundary for leaf functions.\n>\n> Tested on i686 and x86-64. OK for trunk?\n>\n> H.J.\n> ---\n> gcc/\n>\n> PR target/82166\n> * config/i386/i386.c (ix86_finalize_stack_frame_flags): Properly\n> compute the minimum stack alignment. Also update preferred stack\n> boundary when main () is a leaf function.\n>\n> gcc/testsuite/\n>\n> PR target/82166\n> * gcc.target/i386/pr82166.c: New test.\n\nLGTM.\n\nThanks,\nUros.\n\n> ---\n> gcc/config/i386/i386.c | 17 ++++++++++++-----\n> gcc/testsuite/gcc.target/i386/pr82166.c | 14 ++++++++++++++\n> 2 files changed, 26 insertions(+), 5 deletions(-)\n> create mode 100644 gcc/testsuite/gcc.target/i386/pr82166.c\n>\n> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c\n> index 4e93cc1043b..03338e422be 100644\n> --- a/gcc/config/i386/i386.c\n> +++ b/gcc/config/i386/i386.c\n> @@ -14257,11 +14257,12 @@ ix86_finalize_stack_frame_flags (void)\n> unsigned int incoming_stack_boundary\n> = (crtl->parm_stack_boundary > ix86_incoming_stack_boundary\n> ? crtl->parm_stack_boundary : ix86_incoming_stack_boundary);\n> + unsigned int stack_alignment\n> + = (crtl->is_leaf && !ix86_current_function_calls_tls_descriptor\n> + ? crtl->max_used_stack_slot_alignment\n> + : crtl->stack_alignment_needed);\n> unsigned int stack_realign\n> - = (incoming_stack_boundary\n> - < (crtl->is_leaf && !ix86_current_function_calls_tls_descriptor\n> - ? crtl->max_used_stack_slot_alignment\n> - : crtl->stack_alignment_needed));\n> + = (incoming_stack_boundary < stack_alignment);\n> bool recompute_frame_layout_p = false;\n>\n> if (crtl->stack_realign_finalized)\n> @@ -14306,7 +14307,9 @@ ix86_finalize_stack_frame_flags (void)\n> HARD_FRAME_POINTER_REGNUM);\n>\n> /* The preferred stack alignment is the minimum stack alignment. */\n> - unsigned int stack_alignment = crtl->preferred_stack_boundary;\n> + if (stack_alignment > crtl->preferred_stack_boundary)\n> + stack_alignment = crtl->preferred_stack_boundary;\n> +\n> bool require_stack_frame = false;\n>\n> FOR_EACH_BB_FN (bb, cfun)\n> @@ -14349,6 +14352,10 @@ ix86_finalize_stack_frame_flags (void)\n> = incoming_stack_boundary;\n> crtl->stack_alignment_needed\n> = incoming_stack_boundary;\n> + /* Also update preferred_stack_boundary for leaf\n> + functions. */\n> + crtl->preferred_stack_boundary\n> + = incoming_stack_boundary;\n> }\n> }\n> else\n> diff --git a/gcc/testsuite/gcc.target/i386/pr82166.c b/gcc/testsuite/gcc.target/i386/pr82166.c\n> new file mode 100644\n> index 00000000000..8bc63e15231\n> --- /dev/null\n> +++ b/gcc/testsuite/gcc.target/i386/pr82166.c\n> @@ -0,0 +1,14 @@\n> +/* { dg-do compile } */\n> +/* { dg-options \"-Os\" } */\n> +\n> +void foo (void);\n> +int a, b, c;\n> +int\n> +main (void)\n> +{\n> + int j;\n> + for (; c;)\n> + a = b;\n> + for (; j;)\n> + foo ();\n> +}\n> --\n> 2.13.5\n>","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":["patchwork-incoming@bilbo.ozlabs.org","mailing list gcc-patches@gcc.gnu.org"],"Authentication-Results":["ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=gcc.gnu.org\n\t(client-ip=209.132.180.131; helo=sourceware.org;\n\tenvelope-from=gcc-patches-return-462330-incoming=patchwork.ozlabs.org@gcc.gnu.org;\n\treceiver=)","ozlabs.org; dkim=pass (1024-bit key;\n\tunprotected) header.d=gcc.gnu.org header.i=@gcc.gnu.org\n\theader.b=\"k7T9N3wr\"; dkim-atps=neutral","sourceware.org; auth=none"],"Received":["from sourceware.org (server1.sourceware.org [209.132.180.131])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256\n\tbits)) (No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3xwD2z0gZkz9sPm\n\tfor ;\n\tMon, 18 Sep 2017 01:44:26 +1000 (AEST)","(qmail 110475 invoked by alias); 17 Sep 2017 15:44:20 -0000","(qmail 110456 invoked by uid 89); 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Lu\" ","Cc":"\"gcc-patches@gcc.gnu.org\" ","Content-Type":"text/plain; charset=\"UTF-8\""}}]