From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1285) id EDEF53858D35; Wed, 9 Nov 2022 11:32:25 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org EDEF53858D35 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1667993545; bh=+dk3T7q7q0JQaYB2tVzOhj9MwRVkyQUWpkUfIwioDZ0=; h=From:To:Subject:Date:From; b=WPcJSgcDDN6e2FBNq7XuqHiO75tEDbdQSxHhCqY/vnIERW5BrwHDCb0Kki/oKyQaM e4+aoBLx8TRZn5ZNO1/B9JQZaI14VhecPmjQwdke787kHQRecdi102JfKHz+xmfACx asm46650xWpGBIJimV5Tbg0tiFcI3GLjvOPSTvlg= MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Eric Botcazou To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-8901] Restore RTL alias analysis for hard frame pointer X-Act-Checkin: gcc X-Git-Author: Eric Botcazou X-Git-Refname: refs/heads/releases/gcc-12 X-Git-Oldrev: 253a85be59cba7fd9243b0b3e14b1ed5001acc81 X-Git-Newrev: 6e40f57f87c245c6aab361dcabe04c4135cf5f0a Message-Id: <20221109113225.EDEF53858D35@sourceware.org> Date: Wed, 9 Nov 2022 11:32:25 +0000 (GMT) List-Id: https://gcc.gnu.org/g:6e40f57f87c245c6aab361dcabe04c4135cf5f0a commit r12-8901-g6e40f57f87c245c6aab361dcabe04c4135cf5f0a Author: Eric Botcazou Date: Sat Oct 29 10:16:18 2022 +0200 Restore RTL alias analysis for hard frame pointer The change: 2021-07-28 Bin Cheng alias.c (init_alias_analysis): Don't skip prologue/epilogue. broke the alias analysis for the hard frame pointer (when it is used as a frame pointer, i.e. when the frame pointer is not eliminated) described in the large comment at the top of the file, because static_reg_base_value is set for it and, consequently, new_reg_base_value too. When the instruction saving the stack pointer into the hard frame pointer in the prologue is processed, it is viewed as a second set of the hard frame pointer and to a different value by record_set, which then proceeds to reset new_reg_base_value to 0 and the game is over. gcc/ * alias.cc (init_alias_analysis): Do not record sets to the hard frame pointer if the frame pointer has not been eliminated. Diff: --- gcc/alias.cc | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/gcc/alias.cc b/gcc/alias.cc index d54feb15268..c62837dd854 100644 --- a/gcc/alias.cc +++ b/gcc/alias.cc @@ -3369,6 +3369,10 @@ memory_modified_in_insn_p (const_rtx mem, const_rtx insn) void init_alias_analysis (void) { + const bool frame_pointer_eliminated + = reload_completed + && !frame_pointer_needed + && targetm.can_eliminate (FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM); unsigned int maxreg = max_reg_num (); int changed, pass; int i; @@ -3446,12 +3450,8 @@ init_alias_analysis (void) for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) if (static_reg_base_value[i] /* Don't treat the hard frame pointer as special if we - eliminated the frame pointer to the stack pointer instead. */ - && !(i == HARD_FRAME_POINTER_REGNUM - && reload_completed - && !frame_pointer_needed - && targetm.can_eliminate (FRAME_POINTER_REGNUM, - STACK_POINTER_REGNUM))) + eliminated the frame pointer to the stack pointer. */ + && !(i == HARD_FRAME_POINTER_REGNUM && frame_pointer_eliminated)) { new_reg_base_value[i] = static_reg_base_value[i]; bitmap_set_bit (reg_seen, i); @@ -3467,10 +3467,15 @@ init_alias_analysis (void) { rtx note, set; + /* Treat the hard frame pointer as special unless we + eliminated the frame pointer to the stack pointer. */ + if (!frame_pointer_eliminated + && modified_in_p (hard_frame_pointer_rtx, insn)) + continue; + /* If this insn has a noalias note, process it, Otherwise, scan for sets. A simple set will have no side effects which could change the base value of any other register. */ - if (GET_CODE (PATTERN (insn)) == SET && REG_NOTES (insn) != 0 && find_reg_note (insn, REG_NOALIAS, NULL_RTX))