From mboxrd@z Thu Jan 1 00:00:00 1970 From: Luc Van Oostenryck Subject: [PATCH] fix: __builtin_bswap{16,32,64}() constantness Date: Tue, 20 Jun 2017 18:42:53 +0200 Message-ID: <20170620164253.76292-1-luc.vanoostenryck@gmail.com> Return-path: Received: from mail-qk0-f196.google.com ([209.85.220.196]:35840 "EHLO mail-qk0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751128AbdFTQnC (ORCPT ); Tue, 20 Jun 2017 12:43:02 -0400 Received: by mail-qk0-f196.google.com with SMTP id r62so11680287qkf.3 for ; Tue, 20 Jun 2017 09:43:01 -0700 (PDT) Sender: linux-sparse-owner@vger.kernel.org List-Id: linux-sparse@vger.kernel.org To: linux-sparse@vger.kernel.org Cc: Christopher Li , Luc Van Oostenryck When expanding those builtins, we directly excludes a non-constant arg (via the expression expansion cost) and the to retrieve the value we use const_expression_value(). But const_expression_value() is to be used for expressions that qualify as 'integer constant expression' as per the C standard. However we want to be able to use this builtin with all integer expressions having a known value at compile time, even those not qualified as true 'integer constant expression'. Fix this by using get_expression_value_silent() instead of const_expression_value(). Note: this bug was found by testing sparse on the git tree on ARM64. Signed-off-by: Luc Van Oostenryck --- builtin.c | 4 +++- validation/builtin-bswap-constant.c | 6 ++++++ 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/builtin.c b/builtin.c index dbb81032b..4f2a106cb 100644 --- a/builtin.c +++ b/builtin.c @@ -179,13 +179,15 @@ static struct symbol_op choose_op = { /* The argument is constant and valid if the cost is zero */ static int expand_bswap(struct expression *expr, int cost) { + struct expression *arg; long long val; if (cost) return cost; /* the arguments number & type have already been checked */ - val = const_expression_value(first_expression(expr->args)); + arg = first_expression(expr->args); + val = get_expression_value_silent(arg); switch (expr->ctype->bit_size) { case 16: expr->value = __builtin_bswap16(val); break; case 32: expr->value = __builtin_bswap32(val); break; diff --git a/validation/builtin-bswap-constant.c b/validation/builtin-bswap-constant.c index 4560f67e9..18574d4c5 100644 --- a/validation/builtin-bswap-constant.c +++ b/validation/builtin-bswap-constant.c @@ -16,6 +16,12 @@ unsigned long long bswap64(void) return __builtin_bswap64(0x123456789abcdef0ULL); } +unsigned int half_constant(void); +unsigned int half_constant(void) +{ + int v = 0x12345678; + return __builtin_bswap32(v); +} /* * check-name: builtin-bswap-constant * check-command: test-linearize $file -- 2.13.0