From patchwork Thu Apr 17 10:34:05 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Maydell X-Patchwork-Id: 339836 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 07F36140088 for ; Thu, 17 Apr 2014 20:37:02 +1000 (EST) Received: from localhost ([::1]:59418 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wajgh-0002TG-RQ for incoming@patchwork.ozlabs.org; Thu, 17 Apr 2014 06:36:59 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50694) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Waje5-0007f3-T0 for qemu-devel@nongnu.org; Thu, 17 Apr 2014 06:34:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Waje3-0002Pj-SX for qemu-devel@nongnu.org; Thu, 17 Apr 2014 06:34:17 -0400 Received: from mnementh.archaic.org.uk ([2001:8b0:1d0::1]:47842) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Waje3-0002OB-Ki for qemu-devel@nongnu.org; Thu, 17 Apr 2014 06:34:15 -0400 Received: from pm215 by mnementh.archaic.org.uk with local (Exim 4.80) (envelope-from ) id 1Wajdy-00022g-1c for qemu-devel@nongnu.org; Thu, 17 Apr 2014 11:34:10 +0100 From: Peter Maydell To: qemu-devel@nongnu.org Date: Thu, 17 Apr 2014 11:34:05 +0100 Message-Id: <1397730846-7576-51-git-send-email-peter.maydell@linaro.org> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1397730846-7576-1-git-send-email-peter.maydell@linaro.org> References: <1397730846-7576-1-git-send-email-peter.maydell@linaro.org> X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2001:8b0:1d0::1 Subject: [Qemu-devel] [PULL 50/51] arm: translate.c: Fix smlald Instruction X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Peter Crosthwaite The smlald (and probably smlsld) instruction was doing incorrect sign extensions of the operands amongst 64bit result calculation. The instruction psuedo-code is: operand2 = if m_swap then ROR(R[m],16) else R[m]; product1 = SInt(R[n]<15:0>) * SInt(operand2<15:0>); product2 = SInt(R[n]<31:16>) * SInt(operand2<31:16>); result = product1 + product2 + SInt(R[dHi]:R[dLo]); R[dHi] = result<63:32>; R[dLo] = result<31:0>; The result calculation should be done in 64 bit arithmetic, and hence product1 and product2 should be sign extended to 64b before calculation. The current implementation was adding product1 and product2 together then sign-extending the intermediate result leading to false negatives. E.G. if product1 = product2 = 0x4000000, their sum = 0x80000000, which will be incorrectly interpreted as -ve on sign extension. We fix by doing the 64b extensions on both product1 and product2 before any addition/subtraction happens. We also fix where we were possibly incorrectly setting the Q saturation flag for SMLSLD, which the ARM ARM specifically says is not set. Reported-by: Christina Smith Signed-off-by: Peter Crosthwaite Reviewed-by: Peter Maydell Message-id: 2cddb6f5a15be4ab8d2160f3499d128ae93d304d.1397704570.git.peter.crosthwaite@xilinx.com Cc: qemu-stable@nongnu.org Signed-off-by: Peter Maydell --- target-arm/translate.c | 34 +++++++++++++++++++++++----------- 1 file changed, 23 insertions(+), 11 deletions(-) diff --git a/target-arm/translate.c b/target-arm/translate.c index 0c08cc1..a4d920b 100644 --- a/target-arm/translate.c +++ b/target-arm/translate.c @@ -8430,27 +8430,39 @@ static void disas_arm_insn(CPUARMState * env, DisasContext *s) if (insn & (1 << 5)) gen_swap_half(tmp2); gen_smul_dual(tmp, tmp2); - if (insn & (1 << 6)) { - /* This subtraction cannot overflow. */ - tcg_gen_sub_i32(tmp, tmp, tmp2); - } else { - /* This addition cannot overflow 32 bits; - * however it may overflow considered as a signed - * operation, in which case we must set the Q flag. - */ - gen_helper_add_setq(tmp, cpu_env, tmp, tmp2); - } - tcg_temp_free_i32(tmp2); if (insn & (1 << 22)) { /* smlald, smlsld */ + TCGv_i64 tmp64_2; + tmp64 = tcg_temp_new_i64(); + tmp64_2 = tcg_temp_new_i64(); tcg_gen_ext_i32_i64(tmp64, tmp); + tcg_gen_ext_i32_i64(tmp64_2, tmp2); tcg_temp_free_i32(tmp); + tcg_temp_free_i32(tmp2); + if (insn & (1 << 6)) { + tcg_gen_sub_i64(tmp64, tmp64, tmp64_2); + } else { + tcg_gen_add_i64(tmp64, tmp64, tmp64_2); + } + tcg_temp_free_i64(tmp64_2); gen_addq(s, tmp64, rd, rn); gen_storeq_reg(s, rd, rn, tmp64); tcg_temp_free_i64(tmp64); } else { /* smuad, smusd, smlad, smlsd */ + if (insn & (1 << 6)) { + /* This subtraction cannot overflow. */ + tcg_gen_sub_i32(tmp, tmp, tmp2); + } else { + /* This addition cannot overflow 32 bits; + * however it may overflow considered as a + * signed operation, in which case we must set + * the Q flag. + */ + gen_helper_add_setq(tmp, cpu_env, tmp, tmp2); + } + tcg_temp_free_i32(tmp2); if (rd != 15) { tmp2 = load_reg(s, rd);