From mboxrd@z Thu Jan 1 00:00:00 1970 From: Luc Van Oostenryck Subject: [PATCH v2 6/8] transform (A & M) >> S to (A >> S) & (M >> S) Date: Mon, 7 Aug 2017 21:12:03 +0200 Message-ID: <20170807191205.86590-7-luc.vanoostenryck@gmail.com> References: <20170807191205.86590-1-luc.vanoostenryck@gmail.com> Return-path: Received: from mail-wm0-f68.google.com ([74.125.82.68]:38353 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751919AbdHGTMS (ORCPT ); Mon, 7 Aug 2017 15:12:18 -0400 Received: by mail-wm0-f68.google.com with SMTP id y206so2036263wmd.5 for ; Mon, 07 Aug 2017 12:12:17 -0700 (PDT) In-Reply-To: <20170807191205.86590-1-luc.vanoostenryck@gmail.com> Sender: linux-sparse-owner@vger.kernel.org List-Id: linux-sparse@vger.kernel.org To: Dibyendu Majumdar Cc: linux-sparse@vger.kernel.org, Luc Van Oostenryck This is especially usefull when simplifying code accessing bitfields. Signed-off-by: Luc Van Oostenryck --- simplify.c | 29 ++++++++++++++++++++++++++++- validation/bitfield-size.c | 4 +--- 2 files changed, 29 insertions(+), 4 deletions(-) diff --git a/simplify.c b/simplify.c index 9893613da..f1a898700 100644 --- a/simplify.c +++ b/simplify.c @@ -412,6 +412,32 @@ static int simplify_asr(struct instruction *insn, pseudo_t pseudo, long long val return 0; } +static int simplify_lsr(struct instruction *insn, pseudo_t pseudo, long long value) +{ + struct instruction *def; + unsigned long long mask; + + if (!value) + return replace_with_pseudo(insn, pseudo); + switch (def_opcode(insn->src1)) { + case OP_AND: + // replace (A & M) >> S + // by (A >> S) & (M >> S) + def = insn->src1->def; + if (!constant(def->src2)) + break; + if (nbr_pseudo_users(insn->src1) > 1) + break; + mask = def->src2->value; + def->opcode = OP_LSR; + def->src2 = value_pseudo(value); + insn->opcode = OP_AND; + insn->src2 = value_pseudo(mask >> value); + return REPEAT_CSE; + } + return 0; +} + static int simplify_mul_div(struct instruction *insn, long long value) { unsigned long long sbit = 1ULL << (insn->size - 1); @@ -562,13 +588,14 @@ static int simplify_constant_rightside(struct instruction *insn) case OP_ADD: case OP_OR: case OP_XOR: case OP_SHL: - case OP_LSR: case_neutral_zero: if (!value) return replace_with_pseudo(insn, insn->src1); return 0; case OP_ASR: return simplify_asr(insn, insn->src1, value); + case OP_LSR: + return simplify_lsr(insn, insn->src1, value); case OP_MODU: case OP_MODS: if (value == 1) diff --git a/validation/bitfield-size.c b/validation/bitfield-size.c index c8c94bb15..34400479a 100644 --- a/validation/bitfield-size.c +++ b/validation/bitfield-size.c @@ -36,8 +36,6 @@ unsigned int get_pbfi_b(struct bfi *bf) { return bf->b; } * check-output-ignore * * check-output-excludes: cast\\.4 - * check-output-pattern-6-times: cast\\. * check-output-pattern-6-times: lsr\\..*\\$6 - * check-output-pattern-6-times: and\\..*\\$15 - * check-output-pattern-6-times: and\\..*\\$960 + * check-output-pattern-12-times: and\\..*\\$15 */ -- 2.13.2