From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp001-out.apm-internet.net (smtp001-out.apm-internet.net [85.119.248.222]) by sourceware.org (Postfix) with ESMTPS id A303238582B9 for ; Mon, 10 Oct 2022 14:37:27 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org A303238582B9 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=sandoe.co.uk Authentication-Results: sourceware.org; spf=none smtp.mailfrom=sandoe.co.uk Received: (qmail 78584 invoked from network); 10 Oct 2022 14:37:25 -0000 X-APM-Out-ID: 16654126457858 X-APM-Authkey: 257869/1(257869/1) 5 Received: from unknown (HELO ?192.168.1.95?) (81.138.1.83) by smtp001.apm-internet.net with SMTP; 10 Oct 2022 14:37:25 -0000 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.7\)) Subject: Re: [RFC] Add support for vectors in comparisons (like the C++ frontend does) From: Iain Sandoe In-Reply-To: <20221010141141.krpmtzmbgadlo3db@ws2202.lin.mbt.kalray.eu> Date: Mon, 10 Oct 2022 15:37:24 +0100 Cc: GCC Patches , Joseph Myers Content-Transfer-Encoding: quoted-printable Message-Id: References: <20221010141141.krpmtzmbgadlo3db@ws2202.lin.mbt.kalray.eu> To: Paul Iannetta X-Mailer: Apple Mail (2.3608.120.23.2.7) X-Spam-Status: No, score=-13.9 required=5.0 tests=BAYES_00,GIT_PATCH_0,KAM_ASCII_DIVIDERS,KAM_COUK,KAM_DMARC_STATUS,KAM_LAZY_DOMAIN_SECURITY,RCVD_IN_DNSWL_LOW,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Hi Paul, Not a review of the patch - but a couple of observations. > On 10 Oct 2022, at 15:11, Paul Iannetta via Gcc-patches = wrote: > I am trying to bridge the gap between the extensions supported by the = C > and C++ front-ends. When it comes to vector extensions, C++ supports > vectors in comparisons and within conditional expressions whereas the = C > front-end does not. Equivalence seems, on the face of it, a reasonable objective - but I am curious as whether there is some more concrete motivation for the patch, e.g. some codebase that currently does not work but would with this = change? > I have a patch to bring this feature to the C front-end as well, and > would like to hear your opinion on it, especially since it may affect > the feature-set of the objc front-end as well. Likewise, I am interested in the motivation for the ObjC change. The = usual initial filter for consideration of functional changes (at least for the = NeXT runtime on Darwin) is =E2=80=9CWhat does current clang do?=E2=80=9D or, = even better, =E2=80=9Cwhat does current Xcode do?=E2=80=9D. There are several (possibly many) = cases where C in clang has extensions to C++ behaviour - and vice-versa (because = there is a single front-end codebase, that happens easily, whether by design = o accident). The reason for the =E2=80=98clang litmus test=E2=80=99 is that the = effective language standard for ObjectiveC is determined by that compiler. cheers Iain > I have tried to mirror as much as possible what the C++ front-end does > and checked that both front-end produce the same GIMPLE for all the > simple expressions as well as some more complex combinations of the > operators (?:, !, ^, || and &&). >=20 > Currently, this is only a tentative patch and I did not add any tests > to the testsuite. Moreover, the aarch64's target-specific testsuite > explicitly tests the non-presence of this feature, which will have to > be removed. >=20 > I've run the testsuite on x86 and I've not seen any regressions. >=20 > Cheers, > Paul >=20 > # ------------------------ >8 ------------------------ > Support for vector types in simple comparisons >=20 > gcc/ >=20 > * doc/extend.texi: Remove the C++ mention, since both C and C++ > support the all the mentioned features. >=20 > gcc/c/ >=20 > * c-typeck.cc (build_unary_op): Add support for vector for the > unary exclamation mark. > (build_conditional_expr): Add support for vector in conditional > expressions. > (build_binary_op): Add support for vector for &&, || and ^. > (c_objc_common_truthvalue_conversion): Remove the special gards > preventing vector types. >=20 > # ------------------------ >8 ------------------------ > diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc > index 17185fd3da4..03ade14cae9 100644 > --- a/gcc/c/c-typeck.cc > +++ b/gcc/c/c-typeck.cc > @@ -4536,12 +4536,15 @@ build_unary_op (location_t location, enum = tree_code code, tree xarg, > case TRUTH_NOT_EXPR: > if (typecode !=3D INTEGER_TYPE && typecode !=3D FIXED_POINT_TYPE > && typecode !=3D REAL_TYPE && typecode !=3D POINTER_TYPE > - && typecode !=3D COMPLEX_TYPE) > + && typecode !=3D COMPLEX_TYPE && typecode !=3D VECTOR_TYPE) > { > error_at (location, > "wrong type argument to unary exclamation mark"); > return error_mark_node; > } > + if (gnu_vector_type_p (TREE_TYPE (arg))) > + return build_binary_op (location, EQ_EXPR, arg, > + build_zero_cst (TREE_TYPE (arg)), = false); > if (int_operands) > { > arg =3D c_objc_common_truthvalue_conversion (location, xarg); > @@ -5477,6 +5480,129 @@ build_conditional_expr (location_t colon_loc, = tree ifexp, bool ifexp_bcp, > result_type =3D type2; > } >=20 > + if (gnu_vector_type_p (TREE_TYPE (ifexp)) > + && VECTOR_INTEGER_TYPE_P (TREE_TYPE (ifexp))) > + { > + tree ifexp_type =3D TREE_TYPE (ifexp); > + > + /* If ifexp is another cond_expr choosing between -1 and 0, > + then we can use its comparison. It may help to avoid > + additional comparison, produce more accurate diagnostics > + and enables folding. */ > + if (TREE_CODE (ifexp) =3D=3D VEC_COND_EXPR > + && integer_minus_onep (TREE_OPERAND (ifexp, 1)) > + && integer_zerop (TREE_OPERAND (ifexp, 2))) > + ifexp =3D TREE_OPERAND (ifexp, 0); > + > + tree op1_type =3D TREE_TYPE (op1); > + tree op2_type =3D TREE_TYPE (op2); > + > + if (!VECTOR_TYPE_P (op1_type) && !VECTOR_TYPE_P (op2_type)) > + { > + /* Rely on the error messages of the scalar version. */ > + tree scal =3D > + build_conditional_expr (colon_loc, integer_one_node, = ifexp_bcp, > + op1, op1_original_type, op1_loc, > + op2, op2_original_type, op2_loc); > + if (scal =3D=3D error_mark_node) > + return error_mark_node; > + tree stype =3D TREE_TYPE (scal); > + tree ctype =3D TREE_TYPE (ifexp_type); > + if (TYPE_SIZE (stype) !=3D TYPE_SIZE (ctype) > + || (!INTEGRAL_TYPE_P (stype) && !SCALAR_FLOAT_TYPE_P = (stype))) > + { > + error_at (colon_loc, > + "inferred scalar type %qT is not an integer or " > + "floating-point type of the same size as %qT", = stype, > + COMPARISON_CLASS_P (ifexp) > + ? TREE_TYPE (TREE_TYPE (TREE_OPERAND (ifexp, = 0))) > + : ctype); > + return error_mark_node; > + } > + > + tree vtype =3D build_opaque_vector_type (stype, > + TYPE_VECTOR_SUBPARTS > + (ifexp_type)); > + /* The warnings (like Wsign-conversion) have already been > + given by the scalar build_conditional_expr. We still check > + unsafe_conversion_p to forbid truncating long long -> = float. */ > + if (unsafe_conversion_p (stype, op1, NULL_TREE, false)) > + { > + error_at (colon_loc, "conversion of scalar %qT to vector = %qT " > + "involves truncation", op1_type, vtype); > + return error_mark_node; > + } > + if (unsafe_conversion_p (stype, op2, NULL_TREE, false)) > + { > + error_at (colon_loc, "conversion of scalar %qT to vector = %qT " > + "involves truncation", op2_type, vtype); > + return error_mark_node; > + } > + > + op1 =3D convert (stype, op1); > + op1 =3D save_expr (op1); > + op1 =3D build_vector_from_val (vtype, op1); > + op1_type =3D vtype; > + op2 =3D convert (stype, op2); > + op2 =3D save_expr (op2); > + op2 =3D build_vector_from_val (vtype, op2); > + op2_type =3D vtype; > + } > + > + if (gnu_vector_type_p (op1_type) ^ gnu_vector_type_p = (op2_type)) > + { > + enum stv_conv convert_flag =3D > + scalar_to_vector (colon_loc, VEC_COND_EXPR, op1, op2, > + true); > + > + switch (convert_flag) > + { > + case stv_error: > + return error_mark_node; > + case stv_firstarg: > + { > + op1 =3D save_expr (op1); > + op1 =3D convert (TREE_TYPE (op2_type), op1); > + op1 =3D build_vector_from_val (op2_type, op1); > + op1_type =3D TREE_TYPE (op1); > + break; > + } > + case stv_secondarg: > + { > + op2 =3D save_expr (op2); > + op2 =3D convert (TREE_TYPE (op1_type), op2); > + op2 =3D build_vector_from_val (op1_type, op2); > + op2_type =3D TREE_TYPE (op2); > + break; > + } > + default: > + break; > + } > + } > + > + if (!gnu_vector_type_p (op1_type) > + || !gnu_vector_type_p (op2_type) > + || !comptypes (op1_type, op2_type) > + || maybe_ne (TYPE_VECTOR_SUBPARTS (ifexp_type), > + TYPE_VECTOR_SUBPARTS (op1_type)) > + || TYPE_SIZE (ifexp_type) !=3D TYPE_SIZE (op1_type)) > + { > + error_at (colon_loc, > + "incompatible vector types in conditional = expression: " > + "%qT, %qT and %qT", TREE_TYPE (ifexp), > + TREE_TYPE (orig_op1), TREE_TYPE (orig_op2)); > + return error_mark_node; > + } > + > + if (!COMPARISON_CLASS_P (ifexp)) > + { > + tree cmp_type =3D truth_type_for (ifexp_type); > + ifexp =3D build2 (NE_EXPR, cmp_type, ifexp, > + build_zero_cst (ifexp_type)); > + } > + return build3_loc (colon_loc, VEC_COND_EXPR, op1_type, ifexp, = op1, op2); > + } > + > if (!result_type) > { > if (flag_cond_mismatch) > @@ -5522,17 +5648,6 @@ build_conditional_expr (location_t colon_loc, = tree ifexp, bool ifexp_bcp, > && !TREE_OVERFLOW (orig_op2))); > } >=20 > - /* Need to convert condition operand into a vector mask. */ > - if (VECTOR_TYPE_P (TREE_TYPE (ifexp))) > - { > - tree vectype =3D TREE_TYPE (ifexp); > - tree elem_type =3D TREE_TYPE (vectype); > - tree zero =3D build_int_cst (elem_type, 0); > - tree zero_vec =3D build_vector_from_val (vectype, zero); > - tree cmp_type =3D truth_type_for (vectype); > - ifexp =3D build2 (NE_EXPR, cmp_type, ifexp, zero_vec); > - } > - > if (int_const || (ifexp_bcp && TREE_CODE (ifexp) =3D=3D = INTEGER_CST)) > ret =3D fold_build3_loc (colon_loc, COND_EXPR, result_type, ifexp, = op1, op2); > else > @@ -12105,6 +12220,54 @@ build_binary_op (location_t location, enum = tree_code code, > && (op0 =3D=3D truthvalue_true_node > || !TREE_OVERFLOW (orig_op1))); > } > + if (!VECTOR_TYPE_P (type0) && gnu_vector_type_p (type1)) > + { > + if (!COMPARISON_CLASS_P (op1)) > + op1 =3D build_binary_op (EXPR_LOCATION (op1), NE_EXPR, op1, > + build_zero_cst (type1), false); > + if (code =3D=3D TRUTH_ANDIF_EXPR) > + { > + tree z =3D build_zero_cst (TREE_TYPE (op1)); > + return build_conditional_expr (location, op0, 0, > + op1, NULL_TREE, = EXPR_LOCATION (op1), > + z, NULL_TREE, EXPR_LOCATION = (z)); > + } > + else if (code =3D=3D TRUTH_ORIF_EXPR) > + { > + tree m1 =3D build_all_ones_cst (TREE_TYPE (op1)); > + return build_conditional_expr (location, op0, 0, > + m1, NULL_TREE, = EXPR_LOCATION (m1), > + op1, NULL_TREE, = EXPR_LOCATION (op1)); > + } > + else > + gcc_unreachable (); > + } > + if (gnu_vector_type_p (type0) > + && (!VECTOR_TYPE_P (type1) || gnu_vector_type_p (type1))) > + { > + if (!COMPARISON_CLASS_P (op0)) > + op0 =3D build_binary_op (EXPR_LOCATION (op0), NE_EXPR, op0, > + build_zero_cst (type0), false); > + if (!VECTOR_TYPE_P (type1)) > + { > + tree m1 =3D build_all_ones_cst (TREE_TYPE (op0)); > + tree z =3D build_zero_cst (TREE_TYPE (op0)); > + op1 =3D build_conditional_expr (location, op1, 0, > + m1, NULL_TREE, EXPR_LOCATION = (m1), > + z, NULL_TREE, = EXPR_LOCATION(z)); > + } > + else if (!COMPARISON_CLASS_P (op1)) > + op1 =3D build_binary_op (EXPR_LOCATION (op1), NE_EXPR, op1, > + build_zero_cst (type1), false); > + if (code =3D=3D TRUTH_ANDIF_EXPR) > + code =3D BIT_AND_EXPR; > + else if (code =3D=3D TRUTH_ORIF_EXPR) > + code =3D BIT_IOR_EXPR; > + else > + gcc_unreachable (); > + > + return build_binary_op (location, code, op0, op1, false); > + } > break; >=20 > /* Shift operations: result has same type as first operand; > @@ -12906,10 +13069,6 @@ c_objc_common_truthvalue_conversion = (location_t location, tree expr) > case FUNCTION_TYPE: > gcc_unreachable (); >=20 > - case VECTOR_TYPE: > - error_at (location, "used vector type where scalar is = required"); > - return error_mark_node; > - > default: > break; > } > @@ -12924,8 +13083,6 @@ c_objc_common_truthvalue_conversion = (location_t location, tree expr) > expr =3D note_integer_operands (expr); > } > else > - /* ??? Should we also give an error for vectors rather than = leaving > - those to give errors later? */ > expr =3D c_common_truthvalue_conversion (location, expr); >=20 > if (TREE_CODE (expr) =3D=3D INTEGER_CST && int_operands && = !int_const) > diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi > index c89df8778b2..1e0d436c02c 100644 > --- a/gcc/doc/extend.texi > +++ b/gcc/doc/extend.texi > @@ -12007,7 +12007,7 @@ c =3D a > b; /* The result would be @{0, = 0,-1, 0@} */ > c =3D a =3D=3D b; /* The result would be @{0,-1, 0,-1@} */ > @end smallexample >=20 > -In C++, the ternary operator @code{?:} is available. @code{a?b:c}, = where > +The ternary operator @code{?:} is available. @code{a?b:c}, where > @code{b} and @code{c} are vectors of the same type and @code{a} is an > integer vector with the same number of elements of the same size as = @code{b} > and @code{c}, computes all three arguments and creates a vector > @@ -12020,7 +12020,7 @@ vector. If both @code{b} and @code{c} are = scalars and the type of > @code{b} and @code{c} are converted to a vector type whose elements = have > this type and with the same number of elements as @code{a}. >=20 > -In C++, the logic operators @code{!, &&, ||} are available for = vectors. > +The logic operators @code{!, &&, ||} are available for vectors. > @code{!v} is equivalent to @code{v =3D=3D 0}, @code{a && b} is = equivalent to > @code{a!=3D0 & b!=3D0} and @code{a || b} is equivalent to @code{a!=3D0 = | b!=3D0}. > For mixed operations between a scalar @code{s} and a vector @code{v}, >=20 >=20 >=20 >=20