From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2078) id E7A063858D35; Wed, 28 Jun 2023 01:25:49 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E7A063858D35 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1687915549; bh=vp8o3TPTYbhBpN6Bf0EDqxlr4BQGOp2ZP2m8taBJ7DA=; h=From:To:Subject:Date:From; b=e2aKg/srQABSw924lm8fqlrwS41L5csj+XrqUjzxEe50TCL/Z7A1JdlXzBfLUqVrh kvD4/KKx7NKXBWAIDok7MmUAIy9MLDBaRaj/fU5xEFGTY7gSjYk1qUQbKs0TH4h5eb gYEw/mCIa6C4ULdydkJ23wWYUx5w530z7IX2aNIo= MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: hongtao Liu To: gcc-cvs@gcc.gnu.org Subject: [gcc r14-2142] Issue a warning for conversion between short and __bf16 under TARGET_AVX512BF16. X-Act-Checkin: gcc X-Git-Author: liuhongt X-Git-Refname: refs/heads/master X-Git-Oldrev: 878a9fee50b05c63200bd9a9d1e5189b304692ae X-Git-Newrev: 4ae5ad78c32bd775c6da5fd419183d29d6bef38a Message-Id: <20230628012549.E7A063858D35@sourceware.org> Date: Wed, 28 Jun 2023 01:25:49 +0000 (GMT) List-Id: https://gcc.gnu.org/g:4ae5ad78c32bd775c6da5fd419183d29d6bef38a commit r14-2142-g4ae5ad78c32bd775c6da5fd419183d29d6bef38a Author: liuhongt Date: Mon Jun 26 11:46:49 2023 +0800 Issue a warning for conversion between short and __bf16 under TARGET_AVX512BF16. __bfloat16 is redefined from typedef short to real __bf16 since GCC V13. The patch issues an warning for potential silent implicit conversion between __bf16 and short where users may only expect a data movement. To avoid too many false positive, warning is only under TARGET_AVX512BF16. gcc/ChangeLog: * config/i386/i386.cc (ix86_invalid_conversion): New function. (TARGET_INVALID_CONVERSION): Define as ix86_invalid_conversion. gcc/testsuite/ChangeLog: * gcc.target/i386/bf16_short_warn.c: New test. Diff: --- gcc/config/i386/i386.cc | 32 +++++++++++++++++++++++++ gcc/testsuite/gcc.target/i386/bf16_short_warn.c | 17 +++++++++++++ 2 files changed, 49 insertions(+) diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc index caca74d6dec..8989985700a 100644 --- a/gcc/config/i386/i386.cc +++ b/gcc/config/i386/i386.cc @@ -22719,6 +22719,35 @@ x86_emit_floatuns (rtx operands[2]) emit_label (donelab); } + +/* Return the diagnostic message string if conversion from FROMTYPE to + TOTYPE is not allowed, NULL otherwise. + Currently it's used to warn for silent implicit conversion between __bf16 + and short, since __bfloat16 is refined as real __bf16 instead of short + since GCC13. */ + +static const char * +ix86_invalid_conversion (const_tree fromtype, const_tree totype) +{ + if (element_mode (fromtype) != element_mode (totype) + && (TARGET_AVX512BF16 || TARGET_AVXNECONVERT)) + { + /* Warn for silent implicit conversion where user may expect + a bitcast. */ + if ((TYPE_MODE (fromtype) == BFmode + && TYPE_MODE (totype) == HImode) + || (TYPE_MODE (totype) == BFmode + && TYPE_MODE (fromtype) == HImode)) + warning (0, "%<__bfloat16%> is redefined from typedef % " + "to real %<__bf16%> since GCC V13, be careful of " + "implicit conversion between %<__bf16%> and %; " + "a explicit bitcast may be needed here"); + } + + /* Conversion allowed. */ + return NULL; +} + /* Target hook for scalar_mode_supported_p. */ static bool @@ -25010,6 +25039,9 @@ ix86_run_selftests (void) # define TARGET_MERGE_DECL_ATTRIBUTES merge_dllimport_decl_attributes #endif +#undef TARGET_INVALID_CONVERSION +#define TARGET_INVALID_CONVERSION ix86_invalid_conversion + #undef TARGET_COMP_TYPE_ATTRIBUTES #define TARGET_COMP_TYPE_ATTRIBUTES ix86_comp_type_attributes diff --git a/gcc/testsuite/gcc.target/i386/bf16_short_warn.c b/gcc/testsuite/gcc.target/i386/bf16_short_warn.c new file mode 100644 index 00000000000..3e47a815200 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/bf16_short_warn.c @@ -0,0 +1,17 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +#include +typedef struct { +short payload; +} BFloat16; + +__attribute__((target("avx512vl,avx512bf16"))) +BFloat16 tobf16_avx512(float f) +{ + BFloat16 r; + __m128bh m = _mm_cvtneps_pbh(_mm_set_ss(f)); + r.payload = m[0]; /* { dg-warning " be careful of implicit conversion between '__bf16' and 'short'" } */ + return r; +} +