From patchwork Sat Aug 24 14:55:36 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Jambor X-Patchwork-Id: 269639 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "localhost", Issuer "www.qmailtoaster.com" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 144A02C009C for ; Sun, 25 Aug 2013 00:55:48 +1000 (EST) DomainKey-Signature: a=rsa-sha1; c=nofws; d=gcc.gnu.org; h=list-id :list-unsubscribe:list-archive:list-post:list-help:sender:date :from:to:cc:subject:message-id:mime-version:content-type; q=dns; s=default; b=nw2G+qNQdnUD5Cpr8T3PlB1kAWOBvWSRrWJzyeOvP/c23zcNSL q1AJYTm+XQyz6JDM0soDSH4ozwKOZf4RYr1jKWhD7Jx0qGNb0F8NZ0HJmvpP+o5W jCLeh2zz2ZkhuH0JkSviTt+rtGxb0wmxfWd0F2oQDfxvsoYDqC0EJUNjU= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=gcc.gnu.org; h=list-id :list-unsubscribe:list-archive:list-post:list-help:sender:date :from:to:cc:subject:message-id:mime-version:content-type; s= default; bh=+NRCUEEy3LTzXyrT/VHYTKGgQKI=; b=oszeEYb4DheV4ip6BM9z dNvQd6tvBfzMEN2tw5H22j7/EWsM96bDydBfHtxFQai85AyvaxxNFU7QEywuGOkx 81a5pvkEgXxRezt5Bj1rTxY3QAT6E+je9SivK1tabubySZeAUONuc0zXoeFC9lZR RsEtfSYNIZr5CqPylFUkUHQ= Received: (qmail 12300 invoked by alias); 24 Aug 2013 14:55:41 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Delivered-To: mailing list gcc-patches@gcc.gnu.org Received: (qmail 12291 invoked by uid 89); 24 Aug 2013 14:55:40 -0000 X-Spam-SWARE-Status: No, score=-4.9 required=5.0 tests=AWL, BAYES_00, KHOP_RCVD_UNTRUST, RCVD_IN_HOSTKARMA_W, RCVD_IN_HOSTKARMA_WL autolearn=ham version=3.3.2 Received: from cantor2.suse.de (HELO mx2.suse.de) (195.135.220.15) by sourceware.org (qpsmtpd/0.84/v0.84-167-ge50287c) with ESMTP; Sat, 24 Aug 2013 14:55:39 +0000 Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id CBD62A51BB; Sat, 24 Aug 2013 16:55:36 +0200 (CEST) Date: Sat, 24 Aug 2013 16:55:36 +0200 From: Martin Jambor To: GCC Patches Cc: Jan Hubicka Subject: [PATCH] Create pass through and ancestor jump functions even there is dynamic type change Message-ID: <20130824145536.GE32344@virgil.suse> Mail-Followup-To: GCC Patches , Jan Hubicka MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Hi, the patch below does not punt when creating pass through and ancestor jump functions when there is a possible dynamic type change detected but rather clears a flag in those functions. Indirect inlining and IPA-CP then make sure they only propagate when the flag is set. I have also merged one or two pieces of code in IPA-CP that did the same so that I could change behavior at one place only and made update_jump_functions_after_inlining slightly less ugly by not relying on structure copying so much and constructing all but one jump function types with the ipa_set_jf_* methods. Hopefully that will make the rather complicated function less error prone as it apparently gets even more complex over time. Bootstrapped and tested on x86_64-linux. OK for trunk? Thanks, Martin 2013-08-23 Martin Jambor * ipa-prop.h (ipa_pass_through_data): New field type_preserved. (ipa_ancestor_jf_data): Likewise. (ipa_get_jf_pass_through_agg_preserved): Fix comment typo. (ipa_get_jf_pass_through_type_preserved): New function. (ipa_get_jf_ancestor_agg_preserved): Fix comment typo. (ipa_get_jf_ancestor_type_preserved): New function. * ipa-cp.c (ipa_get_jf_pass_through_result): Honor type_preserved flag. (ipa_get_jf_ancestor_result): Likewise. (propagate_vals_accross_pass_through): Use ipa_get_jf_pass_through_result to do all the value mappings. * ipa-prop.c (ipa_print_node_jump_functions_for_edge): Dump the type_preserved flag. (ipa_set_jf_cst_copy): New function. (ipa_set_jf_simple_pass_through): Set the type_preserved flag. (ipa_set_jf_arith_pass_through): Likewise. (ipa_set_ancestor_jf): Likewise. (compute_complex_assign_jump_func): Set type_preserved instead of punting. (ipa_compute_jump_functions_for_edge): Likewise. (combine_known_type_and_ancestor_jfs): Honor type_preserved. (update_jump_functions_after_inlining): Update type_preserved. Explicitely create jump functions when combining one with pass_through. (ipa_write_jump_function): Stream the type_preserved flags. (ipa_read_jump_function): Likewise. Index: src/gcc/ipa-cp.c =================================================================== --- src.orig/gcc/ipa-cp.c 2013-08-22 11:49:25.000000000 +0200 +++ src/gcc/ipa-cp.c 2013-08-23 12:20:04.000000000 +0200 @@ -745,17 +745,26 @@ initialize_node_lattices (struct cgraph_ /* Return the result of a (possibly arithmetic) pass through jump function JFUNC on the constant value INPUT. Return NULL_TREE if that cannot be - determined or itself is considered an interprocedural invariant. */ + determined or be considered an interprocedural invariant. */ static tree ipa_get_jf_pass_through_result (struct ipa_jump_func *jfunc, tree input) { tree restype, res; + if (TREE_CODE (input) == TREE_BINFO) + { + if (ipa_get_jf_pass_through_type_preserved (jfunc)) + { + gcc_checking_assert (ipa_get_jf_pass_through_operation (jfunc) + == NOP_EXPR); + return input; + } + return NULL_TREE; + } + if (ipa_get_jf_pass_through_operation (jfunc) == NOP_EXPR) return input; - else if (TREE_CODE (input) == TREE_BINFO) - return NULL_TREE; gcc_checking_assert (is_gimple_ip_invariant (input)); if (TREE_CODE_CLASS (ipa_get_jf_pass_through_operation (jfunc)) @@ -779,9 +788,13 @@ static tree ipa_get_jf_ancestor_result (struct ipa_jump_func *jfunc, tree input) { if (TREE_CODE (input) == TREE_BINFO) - return get_binfo_at_offset (input, - ipa_get_jf_ancestor_offset (jfunc), - ipa_get_jf_ancestor_type (jfunc)); + { + if (!ipa_get_jf_ancestor_type_preserved (jfunc)) + return NULL; + return get_binfo_at_offset (input, + ipa_get_jf_ancestor_offset (jfunc), + ipa_get_jf_ancestor_type (jfunc)); + } else if (TREE_CODE (input) == ADDR_EXPR) { tree t = TREE_OPERAND (input, 0); @@ -1013,26 +1026,16 @@ propagate_vals_accross_pass_through (str struct ipcp_value *src_val; bool ret = false; - if (ipa_get_jf_pass_through_operation (jfunc) == NOP_EXPR) - for (src_val = src_lat->values; src_val; src_val = src_val->next) - ret |= add_scalar_value_to_lattice (dest_lat, src_val->value, cs, - src_val, src_idx); /* Do not create new values when propagating within an SCC because if there are arithmetic functions with circular dependencies, there is infinite number of them and we would just make lattices bottom. */ - else if (edge_within_scc (cs)) + if ((ipa_get_jf_pass_through_operation (jfunc) != NOP_EXPR) + and edge_within_scc (cs)) ret = set_lattice_contains_variable (dest_lat); else for (src_val = src_lat->values; src_val; src_val = src_val->next) { - tree cstval = src_val->value; - - if (TREE_CODE (cstval) == TREE_BINFO) - { - ret |= set_lattice_contains_variable (dest_lat); - continue; - } - cstval = ipa_get_jf_pass_through_result (jfunc, cstval); + tree cstval = ipa_get_jf_pass_through_result (jfunc, src_val->value); if (cstval) ret |= add_scalar_value_to_lattice (dest_lat, cstval, cs, src_val, Index: src/gcc/ipa-prop.c =================================================================== --- src.orig/gcc/ipa-prop.c 2013-08-22 11:49:25.000000000 +0200 +++ src/gcc/ipa-prop.c 2013-08-23 12:04:13.000000000 +0200 @@ -257,6 +257,8 @@ ipa_print_node_jump_functions_for_edge ( } if (jump_func->value.pass_through.agg_preserved) fprintf (f, ", agg_preserved"); + if (jump_func->value.pass_through.type_preserved) + fprintf (f, ", type_preserved"); fprintf (f, "\n"); } else if (type == IPA_JF_ANCESTOR) @@ -268,6 +270,8 @@ ipa_print_node_jump_functions_for_edge ( print_generic_expr (f, jump_func->value.ancestor.type, 0); if (jump_func->value.ancestor.agg_preserved) fprintf (f, ", agg_preserved"); + if (jump_func->value.ancestor.type_preserved) + fprintf (f, ", type_preserved"); fprintf (f, "\n"); } @@ -373,6 +377,19 @@ ipa_set_jf_known_type (struct ipa_jump_f jfunc->value.known_type.component_type = component_type; } +/* Set JFUNC to be a copy of another jmp (to be used by jump function + combination code). The two functions will share their rdesc. */ + +static void +ipa_set_jf_cst_copy (struct ipa_jump_func *dst, + struct ipa_jump_func *src) + +{ + gcc_checking_assert (src->type == IPA_JF_CONST); + dst->type = IPA_JF_CONST; + dst->value.constant = src->value.constant; +} + /* Set JFUNC to be a constant jmp function. */ static void @@ -406,13 +423,14 @@ ipa_set_jf_constant (struct ipa_jump_fun /* Set JFUNC to be a simple pass-through jump function. */ static void ipa_set_jf_simple_pass_through (struct ipa_jump_func *jfunc, int formal_id, - bool agg_preserved) + bool agg_preserved, bool type_preserved) { jfunc->type = IPA_JF_PASS_THROUGH; jfunc->value.pass_through.operand = NULL_TREE; jfunc->value.pass_through.formal_id = formal_id; jfunc->value.pass_through.operation = NOP_EXPR; jfunc->value.pass_through.agg_preserved = agg_preserved; + jfunc->value.pass_through.type_preserved = type_preserved; } /* Set JFUNC to be an arithmetic pass through jump function. */ @@ -426,19 +444,22 @@ ipa_set_jf_arith_pass_through (struct ip jfunc->value.pass_through.formal_id = formal_id; jfunc->value.pass_through.operation = operation; jfunc->value.pass_through.agg_preserved = false; + jfunc->value.pass_through.type_preserved = false; } /* Set JFUNC to be an ancestor jump function. */ static void ipa_set_ancestor_jf (struct ipa_jump_func *jfunc, HOST_WIDE_INT offset, - tree type, int formal_id, bool agg_preserved) + tree type, int formal_id, bool agg_preserved, + bool type_preserved) { jfunc->type = IPA_JF_ANCESTOR; jfunc->value.ancestor.formal_id = formal_id; jfunc->value.ancestor.offset = offset; jfunc->value.ancestor.type = type; jfunc->value.ancestor.agg_preserved = agg_preserved; + jfunc->value.ancestor.type_preserved = type_preserved; } /* Extract the acual BINFO being described by JFUNC which must be a known type @@ -1005,12 +1026,13 @@ compute_complex_assign_jump_func (struct ipa_set_jf_arith_pass_through (jfunc, index, op2, gimple_assign_rhs_code (stmt)); } - else if (gimple_assign_single_p (stmt) - && !detect_type_change_ssa (tc_ssa, call, jfunc)) + else if (gimple_assign_single_p (stmt)) { bool agg_p = parm_ref_data_pass_through_p (&parms_ainfo[index], call, tc_ssa); - ipa_set_jf_simple_pass_through (jfunc, index, agg_p); + bool type_p = !detect_type_change_ssa (tc_ssa, call, jfunc); + if (type_p || jfunc->type == IPA_JF_UNKNOWN) + ipa_set_jf_simple_pass_through (jfunc, index, agg_p, type_p); } return; } @@ -1033,13 +1055,16 @@ compute_complex_assign_jump_func (struct || offset < 0) return; - /* Dynamic types are changed only in constructors and destructors and */ + /* Dynamic types are changed in constructors and destructors. */ index = ipa_get_param_decl_index (info, SSA_NAME_VAR (ssa)); - if (index >= 0 - && !detect_type_change (op1, base, call, jfunc, offset)) - ipa_set_ancestor_jf (jfunc, offset, TREE_TYPE (op1), index, - parm_ref_data_pass_through_p (&parms_ainfo[index], - call, ssa)); + if (index >= 0) + { + bool type_p = !detect_type_change (op1, base, call, jfunc, offset); + if (type_p || jfunc->type == IPA_JF_UNKNOWN) + ipa_set_ancestor_jf (jfunc, offset, TREE_TYPE (op1), index, + parm_ref_data_pass_through_p (&parms_ainfo[index], + call, ssa), type_p); + } } /* Extract the base, offset and MEM_REF expression from a statement ASSIGN if @@ -1163,10 +1188,11 @@ compute_complex_ancestor_jump_func (stru return; } - if (!detect_type_change (obj, expr, call, jfunc, offset)) + bool type_p = !detect_type_change (obj, expr, call, jfunc, offset); + if (type_p || jfunc->type == IPA_JF_UNKNOWN) ipa_set_ancestor_jf (jfunc, offset, TREE_TYPE (obj), index, parm_ref_data_pass_through_p (&parms_ainfo[index], - call, parm)); + call, parm), type_p); } /* Given OP which is passed as an actual argument to a called function, @@ -1507,7 +1533,7 @@ ipa_compute_jump_functions_for_edge (str for cycle. */ if (parm_preserved_before_stmt_p (&parms_ainfo[index], call, arg)) { - ipa_set_jf_simple_pass_through (jfunc, index, false); + ipa_set_jf_simple_pass_through (jfunc, index, false, false); continue; } } @@ -1516,13 +1542,14 @@ ipa_compute_jump_functions_for_edge (str if (SSA_NAME_IS_DEFAULT_DEF (arg)) { int index = ipa_get_param_decl_index (info, SSA_NAME_VAR (arg)); - if (index >= 0 - && !detect_type_change_ssa (arg, call, jfunc)) + if (index >= 0) { - bool agg_p; + bool agg_p, type_p; agg_p = parm_ref_data_pass_through_p (&parms_ainfo[index], call, arg); - ipa_set_jf_simple_pass_through (jfunc, index, agg_p); + type_p = !detect_type_change_ssa (arg, call, jfunc); + if (type_p || jfunc->type == IPA_JF_UNKNOWN) + ipa_set_jf_simple_pass_through (jfunc, index, agg_p, type_p); } } else @@ -2130,6 +2157,12 @@ combine_known_type_and_ancestor_jfs (str HOST_WIDE_INT combined_offset; tree combined_type; + if (!ipa_get_jf_ancestor_type_preserved (dst)) + { + dst->type = IPA_JF_UNKNOWN; + return; + } + combined_offset = ipa_get_jf_known_type_offset (src) + ipa_get_jf_ancestor_offset (dst); combined_type = ipa_get_jf_ancestor_type (dst); @@ -2196,6 +2229,8 @@ update_jump_functions_after_inlining (st dst->value.ancestor.formal_id = src->value.pass_through.formal_id; dst->value.ancestor.agg_preserved &= src->value.pass_through.agg_preserved; + dst->value.ancestor.type_preserved &= + src->value.pass_through.type_preserved; } else if (src->type == IPA_JF_ANCESTOR) { @@ -2203,6 +2238,8 @@ update_jump_functions_after_inlining (st dst->value.ancestor.offset += src->value.ancestor.offset; dst->value.ancestor.agg_preserved &= src->value.ancestor.agg_preserved; + dst->value.ancestor.type_preserved &= + src->value.ancestor.type_preserved; } else dst->type = IPA_JF_UNKNOWN; @@ -2216,16 +2253,69 @@ update_jump_functions_after_inlining (st && (dst->value.pass_through.formal_id < ipa_get_cs_argument_count (top))) { - bool agg_p; int dst_fid = dst->value.pass_through.formal_id; src = ipa_get_ith_jump_func (top, dst_fid); - agg_p = dst->value.pass_through.agg_preserved; + bool dst_agg_p = ipa_get_jf_pass_through_agg_preserved (dst); - dst->type = src->type; - dst->value = src->value; + switch (src->type) + { + case IPA_JF_UNKNOWN: + dst->type = IPA_JF_UNKNOWN; + break; + case IPA_JF_KNOWN_TYPE: + ipa_set_jf_known_type (dst, + ipa_get_jf_known_type_offset (src), + ipa_get_jf_known_type_base_type (src), + ipa_get_jf_known_type_base_type (src)); + break; + case IPA_JF_CONST: + ipa_set_jf_cst_copy (dst, src); + break; + + case IPA_JF_PASS_THROUGH: + { + int formal_id = ipa_get_jf_pass_through_formal_id (src); + enum tree_code operation; + operation = ipa_get_jf_pass_through_operation (src); + + if (operation == NOP_EXPR) + { + bool agg_p, type_p; + agg_p = dst_agg_p + && ipa_get_jf_pass_through_agg_preserved (src); + type_p = ipa_get_jf_pass_through_type_preserved (src) + && ipa_get_jf_pass_through_type_preserved (dst); + ipa_set_jf_simple_pass_through (dst, formal_id, + agg_p, type_p); + } + else + { + tree operand = ipa_get_jf_pass_through_operand (src); + ipa_set_jf_arith_pass_through (dst, formal_id, operand, + operation); + } + break; + } + case IPA_JF_ANCESTOR: + { + bool agg_p, type_p; + agg_p = dst_agg_p + && ipa_get_jf_ancestor_agg_preserved (src); + type_p = ipa_get_jf_ancestor_type_preserved (src) + && ipa_get_jf_pass_through_type_preserved (dst); + ipa_set_ancestor_jf (dst, + ipa_get_jf_ancestor_offset (src), + ipa_get_jf_ancestor_type (src), + ipa_get_jf_ancestor_formal_id (src), + agg_p, type_p); + break; + } + default: + gcc_unreachable (); + } if (src->agg.items - && (agg_p || !src->agg.by_ref)) + && (dst_agg_p || !src->agg.by_ref)) { /* Currently we do not produce clobber aggregate jump functions, replace with merging when we do. */ @@ -2234,14 +2324,6 @@ update_jump_functions_after_inlining (st dst->agg.by_ref = src->agg.by_ref; dst->agg.items = vec_safe_copy (src->agg.items); } - - if (!agg_p) - { - if (dst->type == IPA_JF_PASS_THROUGH) - dst->value.pass_through.agg_preserved = false; - else if (dst->type == IPA_JF_ANCESTOR) - dst->value.ancestor.agg_preserved = false; - } } else dst->type = IPA_JF_UNKNOWN; @@ -3709,6 +3791,7 @@ ipa_write_jump_function (struct output_b streamer_write_uhwi (ob, jump_func->value.pass_through.formal_id); bp = bitpack_create (ob->main_stream); bp_pack_value (&bp, jump_func->value.pass_through.agg_preserved, 1); + bp_pack_value (&bp, jump_func->value.pass_through.type_preserved, 1); streamer_write_bitpack (&bp); } else @@ -3723,6 +3806,7 @@ ipa_write_jump_function (struct output_b streamer_write_uhwi (ob, jump_func->value.ancestor.formal_id); bp = bitpack_create (ob->main_stream); bp_pack_value (&bp, jump_func->value.ancestor.agg_preserved, 1); + bp_pack_value (&bp, jump_func->value.ancestor.type_preserved, 1); streamer_write_bitpack (&bp); break; } @@ -3780,7 +3864,9 @@ ipa_read_jump_function (struct lto_input int formal_id = streamer_read_uhwi (ib); struct bitpack_d bp = streamer_read_bitpack (ib); bool agg_preserved = bp_unpack_value (&bp, 1); - ipa_set_jf_simple_pass_through (jump_func, formal_id, agg_preserved); + bool type_preserved = bp_unpack_value (&bp, 1); + ipa_set_jf_simple_pass_through (jump_func, formal_id, agg_preserved, + type_preserved); } else { @@ -3797,8 +3883,10 @@ ipa_read_jump_function (struct lto_input int formal_id = streamer_read_uhwi (ib); struct bitpack_d bp = streamer_read_bitpack (ib); bool agg_preserved = bp_unpack_value (&bp, 1); + bool type_preserved = bp_unpack_value (&bp, 1); - ipa_set_ancestor_jf (jump_func, offset, type, formal_id, agg_preserved); + ipa_set_ancestor_jf (jump_func, offset, type, formal_id, agg_preserved, + type_preserved); break; } } Index: src/gcc/ipa-prop.h =================================================================== --- src.orig/gcc/ipa-prop.h 2013-08-13 19:23:27.000000000 +0200 +++ src/gcc/ipa-prop.h 2013-08-22 13:51:04.000000000 +0200 @@ -117,7 +117,12 @@ struct GTY(()) ipa_pass_through_data aggregate part of the jump function (see description of ipa_agg_jump_function). The flag is used only when the operation is NOP_EXPR. */ - bool agg_preserved; + unsigned agg_preserved : 1; + + /* When set to true, we guarantee that, if there is a C++ object pointed to + by this object, it does not undergo dynamic type change in the course of + functions decribed by this jump function. */ + unsigned type_preserved : 1; }; /* Structure holding data required to describe an ancestor pass-through @@ -132,7 +137,11 @@ struct GTY(()) ipa_ancestor_jf_data /* Number of the caller's formal parameter being passed. */ int formal_id; /* Flag with the same meaning like agg_preserve in ipa_pass_through_data. */ - bool agg_preserved; + unsigned agg_preserved : 1; + /* When set to true, we guarantee that, if there is a C++ object pointed to + by this object, it does not undergo dynamic type change in the course of + functions decribed by this jump function. */ + unsigned type_preserved : 1; }; /* An element in an aggegate part of a jump function describing a known value @@ -264,7 +273,7 @@ ipa_get_jf_pass_through_operation (struc return jfunc->value.pass_through.operation; } -/* Return the agg_preserved flag of a pass through jump functin JFUNC. */ +/* Return the agg_preserved flag of a pass through jump function JFUNC. */ static inline bool ipa_get_jf_pass_through_agg_preserved (struct ipa_jump_func *jfunc) @@ -273,6 +282,15 @@ ipa_get_jf_pass_through_agg_preserved (s return jfunc->value.pass_through.agg_preserved; } +/* Return the type_preserved flag of a pass through jump function JFUNC. */ + +static inline bool +ipa_get_jf_pass_through_type_preserved (struct ipa_jump_func *jfunc) +{ + gcc_checking_assert (jfunc->type == IPA_JF_PASS_THROUGH); + return jfunc->value.pass_through.type_preserved; +} + /* Return the offset of an ancestor jump function JFUNC. */ static inline HOST_WIDE_INT @@ -301,7 +319,7 @@ ipa_get_jf_ancestor_formal_id (struct ip return jfunc->value.ancestor.formal_id; } -/* Return the agg_preserved flag of an ancestor jump functin JFUNC. */ +/* Return the agg_preserved flag of an ancestor jump function JFUNC. */ static inline bool ipa_get_jf_ancestor_agg_preserved (struct ipa_jump_func *jfunc) @@ -310,6 +328,15 @@ ipa_get_jf_ancestor_agg_preserved (struc return jfunc->value.ancestor.agg_preserved; } +/* Return the type_preserved flag of an ancestor jump function JFUNC. */ + +static inline bool +ipa_get_jf_ancestor_type_preserved (struct ipa_jump_func *jfunc) +{ + gcc_checking_assert (jfunc->type == IPA_JF_ANCESTOR); + return jfunc->value.ancestor.type_preserved; +} + /* Summary describing a single formal parameter. */ struct ipa_param_descriptor