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X-CSE-ConnectionGUID: N8BRpWxiQEmsoBy6bLUzGA== X-CSE-MsgGUID: Dp40DqVpSkmKvxyAjViVag== X-IronPort-AV: E=McAfee;i="6700,10204,11111"; a="16216437" X-IronPort-AV: E=Sophos;i="6.08,258,1712646000"; d="scan'208";a="16216437" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by orvoesa109.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2024 11:56:05 -0700 X-CSE-ConnectionGUID: T/04zPo4SeSkhvlbJfVO9A== X-CSE-MsgGUID: vYt8Gfj4T8qkzIl2zHS1bw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,258,1712646000"; d="scan'208";a="42968331" Received: from tassilo.jf.intel.com ([10.54.38.190]) by fmviesa009-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2024 11:56:04 -0700 From: Andi Kleen To: gcc-patches@gcc.gnu.org Cc: Andi Kleen Subject: [PATCH v8 01/12] Improve must tail in RTL backend Date: Sat, 22 Jun 2024 11:54:33 -0700 Message-ID: <20240622185557.1589179-2-ak@linux.intel.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240622185557.1589179-1-ak@linux.intel.com> References: <20240622185557.1589179-1-ak@linux.intel.com> MIME-Version: 1.0 X-Spam-Status: No, score=-10.9 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_EF, GIT_PATCH_0, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org - Give error messages for all causes of non sibling call generation - When giving error messages clear the musttail flag to avoid ICEs - Error out when tree-tailcall failed to mark a must-tail call sibcall. In this case it doesn't know the true reason and only gives a vague message. PR83324 gcc/ChangeLog: * calls.cc (maybe_complain_about_tail_call): Clear must tail flag on error. (expand_call): Give error messages for all musttail failures. --- gcc/calls.cc | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-) diff --git a/gcc/calls.cc b/gcc/calls.cc index 21d78f9779fe..883eb9971257 100644 --- a/gcc/calls.cc +++ b/gcc/calls.cc @@ -1249,6 +1249,7 @@ maybe_complain_about_tail_call (tree call_expr, const char *reason) return; error_at (EXPR_LOCATION (call_expr), "cannot tail-call: %s", reason); + CALL_EXPR_MUST_TAIL_CALL (call_expr) = 0; } /* Fill in ARGS_SIZE and ARGS array based on the parameters found in @@ -2650,7 +2651,13 @@ expand_call (tree exp, rtx target, int ignore) /* The type of the function being called. */ tree fntype; bool try_tail_call = CALL_EXPR_TAILCALL (exp); - bool must_tail_call = CALL_EXPR_MUST_TAIL_CALL (exp); + /* tree-tailcall decided not to do tail calls. Error for the musttail case, + unfortunately we don't know the reason so it's fairly vague. + When tree-tailcall reported an error it already cleared the flag, + so this shouldn't really happen unless the + the musttail pass gave up walking before finding the call. */ + if (!try_tail_call) + maybe_complain_about_tail_call (exp, "other reasons"); int pass; /* Register in which non-BLKmode value will be returned, @@ -3022,10 +3029,21 @@ expand_call (tree exp, rtx target, int ignore) pushed these optimizations into -O2. Don't try if we're already expanding a call, as that means we're an argument. Don't try if there's cleanups, as we know there's code to follow the call. */ - if (currently_expanding_call++ != 0 - || (!flag_optimize_sibling_calls && !CALL_FROM_THUNK_P (exp)) - || args_size.var - || dbg_cnt (tail_call) == false) + if (currently_expanding_call++ != 0) + { + maybe_complain_about_tail_call (exp, "inside another call"); + try_tail_call = 0; + } + if (!flag_optimize_sibling_calls + && !CALL_FROM_THUNK_P (exp) + && !CALL_EXPR_MUST_TAIL_CALL (exp)) + try_tail_call = 0; + if (args_size.var) + { + maybe_complain_about_tail_call (exp, "variable size arguments"); + try_tail_call = 0; + } + if (dbg_cnt (tail_call) == false) try_tail_call = 0; /* Workaround buggy C/C++ wrappers around Fortran routines with @@ -3046,13 +3064,15 @@ expand_call (tree exp, rtx target, int ignore) if (MEM_P (*iter)) { try_tail_call = 0; + maybe_complain_about_tail_call (exp, + "hidden string length argument passed on stack"); break; } } /* If the user has marked the function as requiring tail-call optimization, attempt it. */ - if (must_tail_call) + if (CALL_EXPR_MUST_TAIL_CALL (exp)) try_tail_call = 1; /* Rest of purposes for tail call optimizations to fail. */