[committed v2 3/3] arm: reorder assembler architecture directives [PR101723]

Christophe Lyon christophe.lyon.oss@gmail.com
Fri Aug 6 14:08:56 GMT 2021


On Thu, Aug 5, 2021 at 1:58 PM Richard Earnshaw <rearnsha@arm.com> wrote:

>
> A change to the way gas interprets the .fpu directive in binutils-2.34
> means that issuing .fpu will clear any features set by .arch_extension
> that apply to the floating point or simd units.  This unfortunately
> causes problems for more recent versions of the architecture because
> we currently emit .arch, .arch_extension and .fpu directives at
> different times and try to suppress redundant changes.
>
> This change addresses this by firstly unifying all the places where we
> emit these directives to a single block of code and secondly
> (re)emitting all the directives if any changes have been made to the
> target options.  Whilst this is slightly more than the strict minimum
> it should be enough to catch all cases where a change could have
> happened.  The new code also emits the directives in the order: .arch,
> .fpu, .arch_extension.  This ensures that the additional architectural
> extensions are not removed by a later .fpu directive.
>
> Whilst writing this patch I also noticed that in the corner case where
> the last function to be compiled had a non-standard set of
> architecture flags, the assembler would add an incorrect set of
> derived attributes for the file as a whole.  Instead of reflecting the
> command-line options it would reflect the flags from the last file in
> the function.  To address this I've also added a call to re-emit the
> flags from the asm_file_end callback so the assembler will be in the
> correct state when it finishes processing the intput.
>
> There's some slight churn to the testsuite as a consequence of this,
> because previously we had a hack to suppress emitting a .fpu directive
> for one specific case, but with the new order this is no-longer
> necessary.
>
> gcc/ChangeLog:
>
>         PR target/101723
>         * config/arm/arm-cpus.in (generic-armv7-a): Add quirk to suppress
>         writing .cpu directive in asm output.
>         * config/arm/arm.c (arm_identify_fpu_from_isa): New variable.
>         (arm_last_printed_arch_string): Delete.
>         (arm_last-printed_fpu_string): Delete.
>         (arm_configure_build_target): If use of floating-point/SIMD is
>         disabled, remove all fp/simd related features from the target ISA.
>         (last_arm_targ_options): New variable.
>         (arm_print_asm_arch_directives): Add new parameters.  Change order
>         of emitted directives and handle all cases here.
>         (arm_file_start): Always call arm_print_asm_arch_directives, move
>         all generation of .arch/.arch_extension here.
>         (arm_file_end): Call arm_print_asm_arch.
>         (arm_declare_function_name): Call arm_print_asm_arch_directives
>         instead of printing .arch/.fpu directives directly.
>
> gcc/testsuite/ChangeLog:
>
>         PR target/101723
>         * gcc.target/arm/cortex-m55-nofp-flag-hard.c: Update expected
> output.
>         * gcc.target/arm/cortex-m55-nofp-flag-softfp.c: Likewise.
>         * gcc.target/arm/cortex-m55-nofp-nomve-flag-softfp.c: Likewise.
>         * gcc.target/arm/mve/intrinsics/mve_fpu1.c: Convert to dg-do
> assemble.
>         Add a non-no-op function body.
>         * gcc.target/arm/mve/intrinsics/mve_fpu2.c: Likewise.
>         * gcc.target/arm/pr98636.c (dg-options): Add -mfloat-abi=softfp.
>         * gcc.target/arm/attr-neon.c: Tighten scan-assembler tests.
>         * gcc.target/arm/attr-neon2.c: Use -Ofast, convert test to use
>         check-function-bodies.
>         * gcc.target/arm/attr-neon3.c: Likewise.
>         * gcc.target/arm/pr69245.c: Tighten scan-assembler match, but allow
>         multiple instances.
>         * gcc.target/arm/pragma_fpu_attribute.c: Likewise.
>         * gcc.target/arm/pragma_fpu_attribute_2.c: Likewise.
>


Hi Richard,

There were a couple of typos in the tests updates, fixed as follows:

 Author: Christophe Lyon <christophe.lyon@foss.st.com>
Date:   Fri Aug 6 14:06:44 2021 +0000

    arm: Fix typos for reorder assembler architecture directives [PR101723]

    Two tests had typos preventing them from passing, committed as obvious.

    2021-08-06  Christophe Lyon  <christophe.lyon@foss.st.com>

            gcc/testsuite/
            PR target/101723
            * gcc.target/arm/attr-neon3.c: Fix typo.
            * gcc.target/arm/pragma_fpu_attribute_2.c: Fix typo.

diff --git a/gcc/testsuite/gcc.target/arm/attr-neon3.c
b/gcc/testsuite/gcc.target/arm/attr-neon3.c
index 0fbce6e4cd4..b6171e72d89 100644
--- a/gcc/testsuite/gcc.target/arm/attr-neon3.c
+++ b/gcc/testsuite/gcc.target/arm/attr-neon3.c
@@ -33,7 +33,7 @@ my (float32x2_t __a, float32x2_t __b)
 ** |
 **     vld1.64 {d[0-9]+}, \[r[0-9]+:64\]!
 **     vld1.64 {d[0-9]+}, \[r[0-9]+:64\]
-** }
+** )
 **     ...
 **     bx      lr
 */
diff --git a/gcc/testsuite/gcc.target/arm/pragma_fpu_attribute_2.c
b/gcc/testsuite/gcc.target/arm/pragma_fpu_attribute_2.c
index 3d33b04b787..398d8fff35c 100644
--- a/gcc/testsuite/gcc.target/arm/pragma_fpu_attribute_2.c
+++ b/gcc/testsuite/gcc.target/arm/pragma_fpu_attribute_2.c
@@ -28,5 +28,5 @@ uint32_t restored ()
 /* We can't tell exactly how many times the following tests will match
because
    command-line options may cause additional instances to be generated, but
    each must be present at least once.  */
-/* { dg-final { scan-assembler-times {\.fpu\s+vfpv4\n} } } */
-/* { dg-final { scan-assembler-times {\.fpu\s+vfpv3-d16\n} } } */
+/* { dg-final { scan-assembler {\.fpu\s+vfpv4\n} } } */
+/* { dg-final { scan-assembler {\.fpu\s+vfpv3-d16\n} } } *

Christophe




> ---
>  gcc/config/arm/arm-cpus.in                    |   1 +
>  gcc/config/arm/arm.c                          | 186 ++++++++----------
>  gcc/testsuite/gcc.target/arm/attr-neon.c      |   9 +-
>  gcc/testsuite/gcc.target/arm/attr-neon2.c     |  35 ++--
>  gcc/testsuite/gcc.target/arm/attr-neon3.c     |  48 +++--
>  .../arm/cortex-m55-nofp-flag-hard.c           |   2 +-
>  .../arm/cortex-m55-nofp-flag-softfp.c         |   2 +-
>  .../arm/cortex-m55-nofp-nomve-flag-softfp.c   |   2 +-
>  .../gcc.target/arm/mve/intrinsics/mve_fpu1.c  |   5 +-
>  .../gcc.target/arm/mve/intrinsics/mve_fpu2.c  |   5 +-
>  gcc/testsuite/gcc.target/arm/pr69245.c        |   6 +-
>  gcc/testsuite/gcc.target/arm/pr98636.c        |   3 +-
>  .../gcc.target/arm/pragma_fpu_attribute.c     |   7 +-
>  .../gcc.target/arm/pragma_fpu_attribute_2.c   |   7 +-
>  14 files changed, 169 insertions(+), 149 deletions(-)
>
>


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