<david.br...@hesbynett.no> is bouncing. FYI. I've removed it.
On Wed, Aug 07, 2024 at 01:12:00AM GMT, Alejandro Colomar wrote:
> Hi!
>
> This is ready for review.
>
> v5:
>
> - Add changelog entries.
> - Wording fixes in commit messages.
> - s/sizeof/lengthof/ in comment.
> - CC += David, Florian, Andreas [Qing]
> - Docs: Remove some details about future directions. [Qing]
> - Docs: Add examples. [Qing]
> - Docs: Clarify when __lengthof__ evaluates as a constant expression
> and when it evaluates as a run-time value. [Joseph, Qing]
> - Tests: Use several -Wno-* flags to turn off unwanted warnings.
> [Martin, Joseph]
> - Tests: Merge into the same commit that adds the feature.
> - Tests: Fix style (whitespace).
>
> I won't paste the example program I used for development, since it's the
> same as in v4. Check that cover letter if necessary.
>
> When reviewing, mind that some parts of the code have been blindly
> pasted from sizeof, and might not make much sense; I didn't fully
> understand some parts. However, it seems to behave well, and more or
> less it makes sense. Just be careful about it.
>
> At the bottom of this message is the range-diff against v4.
>
> Have a lovely night!
> Alex
>
>
> BTW, I've tested that there are no regressions:
>
> alx@debian:~/src/gnu/gcc$ find len0 -type f
> len0/host-x86_64-pc-linux-gnu/gcc/testsuite/gcc/gcc.sum
> len0/host-x86_64-pc-linux-gnu/gcc/testsuite/gfortran/gfortran.sum
> len0/host-x86_64-pc-linux-gnu/gcc/testsuite/objc/objc.sum
> len0/host-x86_64-pc-linux-gnu/gcc/testsuite/g++/g++.sum
> len0/x86_64-pc-linux-gnu/libitm/testsuite/libitm.sum
> len0/x86_64-pc-linux-gnu/libgomp/testsuite/libgomp.sum
> len0/x86_64-pc-linux-gnu/libatomic/testsuite/libatomic.sum
> len0/x86_64-pc-linux-gnu/libstdc++-v3/testsuite/libstdc++.sum
> alx@debian:~/src/gnu/gcc$ find len1 -type f
> len1/host-x86_64-pc-linux-gnu/gcc/testsuite/gcc/gcc.sum
> len1/host-x86_64-pc-linux-gnu/gcc/testsuite/gfortran/gfortran.sum
> len1/host-x86_64-pc-linux-gnu/gcc/testsuite/objc/objc.sum
> len1/host-x86_64-pc-linux-gnu/gcc/testsuite/g++/g++.sum
> len1/x86_64-pc-linux-gnu/libitm/testsuite/libitm.sum
> len1/x86_64-pc-linux-gnu/libgomp/testsuite/libgomp.sum
> len1/x86_64-pc-linux-gnu/libatomic/testsuite/libatomic.sum
> len1/x86_64-pc-linux-gnu/libstdc++-v3/testsuite/libstdc++.sum
> alx@debian:~/src/gnu/gcc$ cat <(cd len0; find -type f) \
> | while read f; do
> diff -u "len0/$f" "len1/$f";
> done;
> --- len0/./host-x86_64-pc-linux-gnu/gcc/testsuite/gcc/gcc.sum
> 2024-08-06
> +22:22:44.514175252 +0200
> +++ len1/./host-x86_64-pc-linux-gnu/gcc/testsuite/gcc/gcc.sum
> 2024-08-06
> +23:29:53.693730123 +0200
> @@ -1,4 +1,4 @@
> -Test run by alx on Tue Aug 6 19:28:53 2024
> +Test run by alx on Tue Aug 6 22:49:12 2024
> Native configuration is x86_64-pc-linux-gnu
>
> === gcc tests ===
> @@ -86504,6 +86504,15 @@
> PASS: gcc.dg/large-size-array.c (test for errors, line 19)
> PASS: gcc.dg/large-size-array.c (test for excess errors)
> UNSUPPORTED: gcc.dg/lazy-ptr-test.c
> +PASS: gcc.dg/lengthof-compile.c (test for errors, line 11)
> +PASS: gcc.dg/lengthof-compile.c (test for errors, line 15)
> +PASS: gcc.dg/lengthof-compile.c (test for errors, line 27)
> +PASS: gcc.dg/lengthof-compile.c (test for errors, line 42)
> +PASS: gcc.dg/lengthof-compile.c (test for errors, line 45)
> +PASS: gcc.dg/lengthof-compile.c (test for errors, line 48)
> +PASS: gcc.dg/lengthof-compile.c (test for excess errors)
> +PASS: gcc.dg/lengthof.c (test for excess errors)
> +PASS: gcc.dg/lengthof.c execution test
> PASS: gcc.dg/limits-width-1.c (test for excess errors)
> PASS: gcc.dg/limits-width-2.c (test for excess errors)
> PASS: gcc.dg/live-patching-1.c (test for excess errors)
> @@ -204639,7 +204648,7 @@
>
> === gcc Summary ===
>
> -# of expected passes 199780
> +# of expected passes 199789
> # of unexpected failures 31
> # of unexpected successes 2
> # of expected failures 1463
> --- len0/./host-x86_64-pc-linux-gnu/gcc/testsuite/gfortran/gfortran.sum
> 2024-08-06
> +22:22:44.546175561 +0200
> +++ len1/./host-x86_64-pc-linux-gnu/gcc/testsuite/gfortran/gfortran.sum
> 2024-08-06
> +23:29:53.877731933 +0200
> @@ -1,4 +1,4 @@
> -Test run by alx on Tue Aug 6 19:28:53 2024
> +Test run by alx on Tue Aug 6 22:49:12 2024
> Native configuration is x86_64-pc-linux-gnu
>
> === gfortran tests ===
> --- len0/./host-x86_64-pc-linux-gnu/gcc/testsuite/objc/objc.sum
> 2024-08-06
> +22:22:44.462174752 +0200
> +++ len1/./host-x86_64-pc-linux-gnu/gcc/testsuite/objc/objc.sum
> 2024-08-06
> +23:29:53.845731618 +0200
> @@ -1,4 +1,4 @@
> -Test run by alx on Tue Aug 6 19:28:53 2024
> +Test run by alx on Tue Aug 6 22:49:12 2024
> Native configuration is x86_64-pc-linux-gnu
>
> === objc tests ===
> --- len0/./host-x86_64-pc-linux-gnu/gcc/testsuite/g++/g++.sum
> 2024-08-06
> +22:22:44.622176292 +0200
> +++ len1/./host-x86_64-pc-linux-gnu/gcc/testsuite/g++/g++.sum
> 2024-08-06
> +23:29:53.781730989 +0200
> @@ -1,4 +1,4 @@
> -Test run by alx on Tue Aug 6 19:28:53 2024
> +Test run by alx on Tue Aug 6 22:49:12 2024
> Native configuration is x86_64-pc-linux-gnu
>
> === g++ tests ===
> --- len0/./x86_64-pc-linux-gnu/libitm/testsuite/libitm.sum
> 2024-08-06
> +22:22:46.206191541 +0200
> +++ len1/./x86_64-pc-linux-gnu/libitm/testsuite/libitm.sum
> 2024-08-06
> +23:29:55.573748613 +0200
> @@ -1,4 +1,4 @@
> -Test run by alx on Tue Aug 6 19:28:53 2024
> +Test run by alx on Tue Aug 6 22:49:12 2024
> Native configuration is x86_64-pc-linux-gnu
>
> === libitm tests ===
> --- len0/./x86_64-pc-linux-gnu/libgomp/testsuite/libgomp.sum
> 2024-08-06
> +22:22:45.694186612 +0200
> +++ len1/./x86_64-pc-linux-gnu/libgomp/testsuite/libgomp.sum
> 2024-08-06
> +23:29:54.717740194 +0200
> @@ -1,4 +1,4 @@
> -Test run by alx on Tue Aug 6 19:28:53 2024
> +Test run by alx on Tue Aug 6 22:49:12 2024
> Native configuration is x86_64-pc-linux-gnu
>
> === libgomp tests ===
> --- len0/./x86_64-pc-linux-gnu/libatomic/testsuite/libatomic.sum
> 2024-08-06
> +22:22:46.110190617 +0200
> +++ len1/./x86_64-pc-linux-gnu/libatomic/testsuite/libatomic.sum
> 2024-08-06
> +23:29:55.393746843 +0200
> @@ -1,4 +1,4 @@
> -Test run by alx on Tue Aug 6 19:28:53 2024
> +Test run by alx on Tue Aug 6 22:49:12 2024
> Native configuration is x86_64-pc-linux-gnu
>
> === libatomic tests ===
> --- len0/./x86_64-pc-linux-gnu/libstdc++-v3/testsuite/libstdc++.sum
> 2024-08-06
> +22:22:45.998189539 +0200
> +++ len1/./x86_64-pc-linux-gnu/libstdc++-v3/testsuite/libstdc++.sum
> 2024-08-06
> +23:29:55.137744325 +0200
> @@ -1,4 +1,4 @@
> -Test run by alx on Tue Aug 6 19:28:54 2024
> +Test run by alx on Tue Aug 6 22:49:13 2024
> Native configuration is x86_64-pc-linux-gnu
>
> === libstdc++ tests ===
>
>
>
>
>
> Alejandro Colomar (3):
> gcc/: Rename array_type_nelts() => array_type_nelts_minus_one()
> Merge definitions of array_type_nelts_top()
> c: Add __lengthof__ operator
>
> gcc/c-family/c-common.cc | 26 +++++
> gcc/c-family/c-common.def | 3 +
> gcc/c-family/c-common.h | 2 +
> gcc/c/c-decl.cc | 30 ++++--
> gcc/c/c-fold.cc | 7 +-
> gcc/c/c-parser.cc | 61 +++++++++---
> gcc/c/c-tree.h | 4 +
> gcc/c/c-typeck.cc | 114 ++++++++++++++++++++-
> gcc/config/aarch64/aarch64.cc | 2 +-
> gcc/config/i386/i386.cc | 2 +-
> gcc/cp/cp-tree.h | 1 -
> gcc/cp/decl.cc | 2 +-
> gcc/cp/init.cc | 8 +-
> gcc/cp/lambda.cc | 3 +-
> gcc/cp/operators.def | 1 +
> gcc/cp/tree.cc | 13 ---
> gcc/doc/extend.texi | 23 +++++
> gcc/expr.cc | 8 +-
> gcc/fortran/trans-array.cc | 2 +-
> gcc/fortran/trans-openmp.cc | 4 +-
> gcc/rust/backend/rust-tree.cc | 13 ---
> gcc/rust/backend/rust-tree.h | 2 -
> gcc/target.h | 3 +
> gcc/testsuite/gcc.dg/lengthof-compile.c | 49 +++++++++
> gcc/testsuite/gcc.dg/lengthof.c | 127 ++++++++++++++++++++++++
> gcc/tree.cc | 17 +++-
> gcc/tree.h | 3 +-
> 27 files changed, 451 insertions(+), 79 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/lengthof-compile.c
> create mode 100644 gcc/testsuite/gcc.dg/lengthof.c
>
> Range-diff against v4:
> 1: 73010cb4af6 = 1: 73010cb4af6 gcc/: Rename array_type_nelts() =>
> array_type_nelts_minus_one()
> 2: 2bb966a0a89 ! 2: 9b835478721 Merge definitions of array_type_nelts_top()
> @@ Commit message
> Merge definitions of array_type_nelts_top()
>
> There were two identical definitions, and none of them are available
> - where they are needed for implementing __lengthof__(). Merge them,
> and
> + where they are needed for implementing __lengthof__. Merge them, and
> provide the single definition in gcc/tree.{h,cc}, where it's
> available
> - for __lengthof__().
> + for __lengthof__, which will be added in the following commit.
> +
> + gcc/ChangeLog:
> +
> + * tree.h (array_type_nelts_top):
> + * tree.cc (array_type_nelts_top): Define function (moved from
> + gcc/cp/).
> +
> + gcc/cp/ChangeLog:
> +
> + * cp-tree.h (array_type_nelts_top):
> + * tree.cc (array_type_nelts_top): Remove function (move
> + to gcc/).
> +
> + gcc/rust/ChangeLog:
> +
> + * backend/rust-tree.h (array_type_nelts_top):
> + * backend/rust-tree.cc (array_type_nelts_top): Remove
> function.
>
> Signed-off-by: Alejandro Colomar <a...@kernel.org>
>
> 3: e2dbfc43b14 ! 3: af05d01e68d c: Add __lengthof__() operator (n2529)
> @@ Metadata
> Author: Alejandro Colomar <a...@kernel.org>
>
> ## Commit message ##
> - c: Add __lengthof__() operator (n2529)
> + c: Add __lengthof__ operator
>
> - This operator is similar to sizeof() but can only be applied to an
> - array, and returns its length (number of elements).
> + This operator is similar to sizeof but can only be applied to an
> array,
> + and returns its length (number of elements).
>
> FUTURE DIRECTIONS:
>
> - We could make it work with array parameters to functions, and
> - somehow magically return the length designator of the array,
> - regardless of it being really a pointer.
> + We could make it work with array parameters to functions, and
> + somehow magically return the length designator of the array,
> + regardless of it being really a pointer.
>
> - Link: <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2529.pdf>
> - Link: <https://inbox.sourceware.org/gcc/m8s4oqy--...@tutanota.com/T/>
> - Suggested-by: Xavier Del Campo Romero <xavi....@tutanota.com>
> - Co-developed-by: Martin Uecker <uec...@tugraz.at>
> - Cc: Gabriel Ravier <gabrav...@gmail.com>
> Cc: Joseph Myers <josmy...@redhat.com>
> + Cc: Gabriel Ravier <gabrav...@gmail.com>
> Cc: Jakub Jelinek <ja...@redhat.com>
> Cc: Kees Cook <keesc...@chromium.org>
> Cc: Qing Zhao <qing.z...@oracle.com>
> Cc: Jens Gustedt <jens.gust...@inria.fr>
> + Cc: David Brown <david.br...@hesbynett.no>
> + Cc: Florian Weimer <fwei...@redhat.com>
> + Cc: Andreas Schwab <sch...@linux-m68k.org>
> +
> + gcc/ChangeLog:
> +
> + * doc/extend.texi: Document __lengthof__ operator.
> + * target.h (enum type_context_kind): Add __lengthof__
> operator.
> +
> + gcc/c-family/ChangeLog:
> +
> + * c-common.h:
> + * c-common.def:
> + * c-common.cc (c_lengthof_type): Add __lengthof__ operator.
> +
> + gcc/c/ChangeLog:
> +
> + * c-tree.h
> + (c_expr_lengthof_expr, c_expr_lengthof_type):
> + * c-decl.cc
> + (start_struct, finish_struct):
> + (start_enum, finish_enum):
> + * c-parser.cc
> + (c_parser_sizeof_expression):
> + (c_parser_lengthof_expression):
> + (c_parser_sizeof_or_lengthof_expression):
> + (c_parser_unary_expression):
> + * c-typeck.cc
> + (build_external_ref):
> + (record_maybe_used_decl, pop_maybe_used):
> + (is_top_array_vla):
> + (c_expr_lengthof_expr, c_expr_lengthof_type):
> + Add __lengthof__operator.
> +
> + gcc/cp/ChangeLog:
> +
> + * operators.def: Add __lengthof__ operator.
> +
> + gcc/testsuite/ChangeLog:
> +
> + * gcc.dg/lengthof-compile.c:
> + * gcc.dg/lengthof.c: Add tests for __lengthof__ operator.
> +
> + Link: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2529.pdf
> + Link: https://inbox.sourceware.org/gcc/m8s4oqy--...@tutanota.com/T/
> + Suggested-by: Xavier Del Campo Romero <xavi....@tutanota.com>
> + Co-developed-by: Martin Uecker <uec...@tugraz.at>
> Signed-off-by: Alejandro Colomar <a...@kernel.org>
>
> ## gcc/c-family/c-common.cc ##
> @@ gcc/c/c-typeck.cc: int in_alignof;
> /* The level of nesting inside "sizeof". */
> int in_sizeof;
>
> -+/* The level of nesting inside "sizeof". */
> ++/* The level of nesting inside "lengthof". */
> +int in_lengthof;
> +
> /* The level of nesting inside "typeof". */
> @@ gcc/doc/extend.texi: If the operand of the @code{__alignof__}
> expression is a fu
> +Its syntax is just like @code{sizeof}.
> +The operand must be a complete array type.
> +The operand is not evaluated
> -+if the top-level length designator is an integer constant expression;
> ++if the top-level length designator is an integer constant expression
> ++(in this case, the operator results in a constant expression);
> +and it is evaluated
> -+if the top-level length designator is not an integer constant
> expression.
> ++if the top-level length designator is not an integer constant expression
> ++(in this case, the operator results in a run-time value).
> ++For example:
> +
> -+XXX: Do we want to document the following? I think so.
> -+XXX: It would prevent users from relying on __lengthof__
> -+XXX: for distinguishing arrays from pointers.
> -+XXX: I don't want users to complain in the future
> -+XXX: if this doesn't report errors on function parameters anymore
> -+XXX: and that breaks their assumptions.
> -+In the future,
> -+it might also accept a function parameter with array notation,
> -+an incomplete array whose length is specified by other means,
> -+such as attributes,
> -+or other similar cases.
> ++@smallexample
> ++__lengthof__ (int [7][n++]); // constexpr
> ++__lengthof__ (int [n++][7]); // run-time value
> ++@end smallexample
> +
> @node Inline
> @section An Inline Function is As Fast As a Macro
> @@ gcc/target.h: enum type_context_kind {
> /* Creating objects of type T with static storage duration. */
> TCTX_STATIC_STORAGE,
>
> +
> + ## gcc/testsuite/gcc.dg/lengthof-compile.c (new) ##
> +@@
> ++/* { dg-do compile } */
> ++/* { dg-options "-Wno-declaration-after-statement -Wno-pedantic
> -Wno-vla" } */
> ++
> ++extern int x[];
> ++
> ++void
> ++incomplete (int p[])
> ++{
> ++ unsigned n;
> ++
> ++ n = __lengthof__ (x); /* { dg-error "incomplete" } */
> ++
> ++ /* We want to support the following one in the future,
> ++ but for now it should fail. */
> ++ n = __lengthof__ (p); /* { dg-error "invalid" } */
> ++}
> ++
> ++void
> ++fam (void)
> ++{
> ++ struct {
> ++ int x;
> ++ int fam[];
> ++ } s;
> ++ unsigned n;
> ++
> ++ n = __lengthof__ (s.fam); /* { dg-error "incomplete" } */
> ++}
> ++
> ++void fix_fix (int i, char (*a)[3][5], int (*x)[__lengthof__ (*a)]);
> ++void fix_var (int i, char (*a)[3][i], int (*x)[__lengthof__ (*a)]);
> ++void fix_uns (int i, char (*a)[3][*], int (*x)[__lengthof__ (*a)]);
> ++
> ++void
> ++func (void)
> ++{
> ++ int i3[3];
> ++ int i5[5];
> ++ char c35[3][5];
> ++
> ++ fix_fix (5, &c35, &i3);
> ++ fix_fix (5, &c35, &i5); /* { dg-error "incompatible-pointer-types" }
> */
> ++
> ++ fix_var (5, &c35, &i3);
> ++ fix_var (5, &c35, &i5); /* { dg-error "incompatible-pointer-types" }
> */
> ++
> ++ fix_uns (5, &c35, &i3);
> ++ fix_uns (5, &c35, &i5); /* { dg-error "incompatible-pointer-types" }
> */
> ++}
> +
> + ## gcc/testsuite/gcc.dg/lengthof.c (new) ##
> +@@
> ++/* { dg-do run } */
> ++/* { dg-options "-Wno-declaration-after-statement -Wno-pedantic
> -Wno-vla" } */
> ++
> ++#undef NDEBUG
> ++#include <assert.h>
> ++
> ++void
> ++array (void)
> ++{
> ++ short a[7];
> ++
> ++ assert (__lengthof__ (a) == 7);
> ++ assert (__lengthof__ (long [0]) == 0);
> ++ assert (__lengthof__ (unsigned [99]) == 99);
> ++}
> ++
> ++void
> ++vla (void)
> ++{
> ++ unsigned n;
> ++
> ++ n = 99;
> ++ assert (__lengthof__ (short [n - 10]) == 99 - 10);
> ++
> ++ int v[n / 2];
> ++ assert (__lengthof__ (v) == 99 / 2);
> ++
> ++ n = 0;
> ++ int z[n];
> ++ assert (__lengthof__ (z) == 0);
> ++}
> ++
> ++void
> ++member (void)
> ++{
> ++ struct {
> ++ int a[8];
> ++ } s;
> ++
> ++ assert (__lengthof__ (s.a) == 8);
> ++}
> ++
> ++void
> ++vla_eval (void)
> ++{
> ++ int i;
> ++
> ++ i = 7;
> ++ assert (__lengthof__ (struct {int x;}[i++]) == 7);
> ++ assert (i == 7 + 1);
> ++
> ++ int v[i];
> ++ int (*p)[i];
> ++ p = &v;
> ++ assert (__lengthof__ (*p++) == i);
> ++ assert (p - 1 == &v);
> ++}
> ++
> ++void
> ++inner_vla_noeval (void)
> ++{
> ++ int i;
> ++
> ++ i = 3;
> ++ assert (__lengthof__ (struct {int x[i++];}[3]) == 3);
> ++ assert (i == 3);
> ++}
> ++
> ++void
> ++array_noeval (void)
> ++{
> ++ long a[5];
> ++ long (*p)[__lengthof__ (a)];
> ++
> ++ p = &a;
> ++ assert (__lengthof__ (*p++) == 5);
> ++ assert (p == &a);
> ++}
> ++
> ++void
> ++matrix_zero (void)
> ++{
> ++ int i;
> ++
> ++ assert (__lengthof__ (int [0][4]) == 0);
> ++ i = 3;
> ++ assert (__lengthof__ (int [0][i]) == 0);
> ++}
> ++
> ++void
> ++matrix_fixed (void)
> ++{
> ++ int i;
> ++
> ++ assert (__lengthof__ (int [7][4]) == 7);
> ++ i = 3;
> ++ assert (__lengthof__ (int [7][i]) == 7);
> ++}
> ++
> ++void
> ++matrix_vla (void)
> ++{
> ++ int i, j;
> ++
> ++ i = 7;
> ++ assert (__lengthof__ (int [i++][4]) == 7);
> ++ assert (i == 7 + 1);
> ++
> ++ i = 9;
> ++ j = 3;
> ++ assert (__lengthof__ (int [i++][j]) == 9);
> ++ assert (i == 9 + 1);
> ++}
> ++
> ++int
> ++main (void)
> ++{
> ++ array ();
> ++ vla ();
> ++ member ();
> ++ vla_eval ();
> ++ inner_vla_noeval ();
> ++ array_noeval ();
> ++ matrix_zero ();
> ++ matrix_fixed ();
> ++ matrix_vla ();
> ++}
> 4: 9a691f7f208 < -: ----------- testsuite: Add tests for __lengthof__
> --
> 2.45.2
> -- <https://www.alejandro-colomar.es/>
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