[PATCH][AARCH64][PR target/84882] Add mno-strict-align
Richard Earnshaw (lists)
Richard.Earnshaw@arm.com
Fri May 18 14:51:00 GMT 2018
On 27/03/18 13:58, Sudakshina Das wrote:
> Hi
>
> This patch adds the no variant to -mstrict-align and the corresponding
> function attribute. To enable the function attribute, I have modified
> aarch64_can_inline_p () to allow checks even when the callee function
> has no attribute. The need for this is shown by the new test
> target_attr_18.c.
>
> Testing: Bootstrapped, regtested and added new tests that are copies
> of earlier tests checking -mstrict-align with opposite scan directives.
>
> Is this ok for trunk?
>
> Sudi
>
>
> *** gcc/ChangeLog ***
>
> 2018-03-27 Sudakshina Das <sudi.das@arm.com>
>
> Â Â Â Â * common/config/aarch64/aarch64-common.c (aarch64_handle_option):
> Â Â Â Â Check val before adding MASK_STRICT_ALIGN to opts->x_target_flags.
> Â Â Â Â * config/aarch64/aarch64.opt (mstrict-align): Remove RejectNegative.
> Â Â Â Â * config/aarch64/aarch64.c (aarch64_attributes): Mark allow_neg
> Â Â Â Â as true for strict-align.
> Â Â Â Â (aarch64_can_inline_p): Perform checks even when callee has no
> Â Â Â Â attributes to check for strict alignment.
> Â Â Â Â * doc/extend.texi (AArch64 Function Attributes): Document
> Â Â Â Â no-strict-align.
> Â Â Â Â * doc/invoke.texi: (AArch64 Options): Likewise.
>
> *** gcc/testsuite/ChangeLog ***
>
> 2018-03-27 Sudakshina Das <sudi.das@arm.com>
>
> Â Â Â Â * gcc.target/aarch64/pr84882.c: New test.
> Â Â Â Â * gcc.target/aarch64/target_attr_18.c: Likewise.
>
> strict-align.diff
>
>
> diff --git a/gcc/common/config/aarch64/aarch64-common.c b/gcc/common/config/aarch64/aarch64-common.c
> index 7fd9305..d5655a0 100644
> --- a/gcc/common/config/aarch64/aarch64-common.c
> +++ b/gcc/common/config/aarch64/aarch64-common.c
> @@ -97,7 +97,10 @@ aarch64_handle_option (struct gcc_options *opts,
> return true;
>
> case OPT_mstrict_align:
> - opts->x_target_flags |= MASK_STRICT_ALIGN;
> + if (val)
> + opts->x_target_flags |= MASK_STRICT_ALIGN;
> + else
> + opts->x_target_flags &= ~MASK_STRICT_ALIGN;
> return true;
>
> case OPT_momit_leaf_frame_pointer:
> diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
> index 4b5183b..4f35a6c 100644
> --- a/gcc/config/aarch64/aarch64.c
> +++ b/gcc/config/aarch64/aarch64.c
> @@ -11277,7 +11277,7 @@ static const struct aarch64_attribute_info aarch64_attributes[] =
> { "fix-cortex-a53-843419", aarch64_attr_bool, true, NULL,
> OPT_mfix_cortex_a53_843419 },
> { "cmodel", aarch64_attr_enum, false, NULL, OPT_mcmodel_ },
> - { "strict-align", aarch64_attr_mask, false, NULL, OPT_mstrict_align },
> + { "strict-align", aarch64_attr_mask, true, NULL, OPT_mstrict_align },
> { "omit-leaf-frame-pointer", aarch64_attr_bool, true, NULL,
> OPT_momit_leaf_frame_pointer },
> { "tls-dialect", aarch64_attr_enum, false, NULL, OPT_mtls_dialect_ },
> @@ -11640,16 +11640,13 @@ aarch64_can_inline_p (tree caller, tree callee)
> tree caller_tree = DECL_FUNCTION_SPECIFIC_TARGET (caller);
> tree callee_tree = DECL_FUNCTION_SPECIFIC_TARGET (callee);
>
> - /* If callee has no option attributes, then it is ok to inline. */
> - if (!callee_tree)
> - return true;
I think it's still useful to spot the case where both callee_tree and
caller_tree are NULL. In that case both options will pick up
target_option_default_node and will always be compatible; so you can
short-circuit that case, which is the most likely scenario.
> -
> struct cl_target_option *caller_opts
> = TREE_TARGET_OPTION (caller_tree ? caller_tree
> : target_option_default_node);
>
> - struct cl_target_option *callee_opts = TREE_TARGET_OPTION (callee_tree);
> -
> + struct cl_target_option *callee_opts
> + = TREE_TARGET_OPTION (callee_tree ? callee_tree
> + : target_option_default_node);
>
> /* Callee's ISA flags should be a subset of the caller's. */
> if ((caller_opts->x_aarch64_isa_flags & callee_opts->x_aarch64_isa_flags)
> diff --git a/gcc/config/aarch64/aarch64.opt b/gcc/config/aarch64/aarch64.opt
> index 52eaf8c..1426b45 100644
> --- a/gcc/config/aarch64/aarch64.opt
> +++ b/gcc/config/aarch64/aarch64.opt
> @@ -85,7 +85,7 @@ Target RejectNegative Joined Enum(cmodel) Var(aarch64_cmodel_var) Init(AARCH64_C
> Specify the code model.
>
> mstrict-align
> -Target Report RejectNegative Mask(STRICT_ALIGN) Save
> +Target Report Mask(STRICT_ALIGN) Save
> Don't assume that unaligned accesses are handled by the system.
>
> momit-leaf-frame-pointer
> diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
> index 93a0ebc..dcda216 100644
> --- a/gcc/doc/extend.texi
> +++ b/gcc/doc/extend.texi
> @@ -3605,8 +3605,10 @@ for the command line option @option{-mcmodel=}.
> @item strict-align
Other targets add an @itemx for the no-variant.
> @cindex @code{strict-align} function attribute, AArch64
> Indicates that the compiler should not assume that unaligned memory references
> -are handled by the system. The behavior is the same as for the command-line
> -option @option{-mstrict-align}.
> +are handled by the system. To allow the compiler to assume that aligned memory
> +references are handled by the system, the inverse attribute
> +@code{no-strict-align} can be specified. The behavior is the same as for the
> +command-line option @option{-mstrict-align} and @option{-mno-strict-align}.
You've two options now, so 'options'.
>
> @item omit-leaf-frame-pointer
> @cindex @code{omit-leaf-frame-pointer} function attribute, AArch64
> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> index feacd56..0574d21 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -596,7 +596,7 @@ Objective-C and Objective-C++ Dialects}.
> @gccoptlist{-mabi=@var{name} -mbig-endian -mlittle-endian @gol
> -mgeneral-regs-only @gol
> -mcmodel=tiny -mcmodel=small -mcmodel=large @gol
> --mstrict-align @gol
> +-mstrict-align -mno-strict-align @gol
> -momit-leaf-frame-pointer @gol
> -mtls-dialect=desc -mtls-dialect=traditional @gol
> -mtls-size=@var{size} @gol
> @@ -14601,9 +14601,11 @@ Generate code for the large code model. This makes no assumptions about
> addresses and sizes of sections. Programs can be statically linked only.
>
> @item -mstrict-align
> +@itemx -mno-strict-align
> @opindex mstrict-align
> -Avoid generating memory accesses that may not be aligned on a natural object
> -boundary as described in the architecture specification.
> +@opindex mno-strict-align
> +Avoid or allow generating memory accesses that may not be aligned on a natural
> +object boundary as described in the architecture specification.
>
> @item -momit-leaf-frame-pointer
> @itemx -mno-omit-leaf-frame-pointer
> diff --git a/gcc/testsuite/gcc.target/aarch64/pr84882.c b/gcc/testsuite/gcc.target/aarch64/pr84882.c
> new file mode 100644
> index 0000000..ffc7d55
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/pr84882.c
> @@ -0,0 +1,33 @@
> +/* This is a copy of pr71727.c with scanning reversed. */
> +/* { dg-do compile } */
> +/* { dg-options "-mstrict-align -O3 -mno-strict-align" } */
> +
> +struct test_struct_s
> +{
> + long a;
> + long b;
> + long c;
> + long d;
> + unsigned long e;
> +};
> +
> +
> +char _a;
> +struct test_struct_s xarray[128];
> +
> +void
> +_start (void)
> +{
> + struct test_struct_s *new_entry;
> +
> + new_entry = &xarray[0];
> + new_entry->a = 1;
> + new_entry->b = 2;
> + new_entry->c = 3;
> + new_entry->d = 4;
> + new_entry->e = 5;
> +
> + return;
> +}
> +
> +/* { dg-final { scan-assembler "add\tx[0-9]+, x[0-9]+, :" {target lp64} } } */
> diff --git a/gcc/testsuite/gcc.target/aarch64/target_attr_18.c b/gcc/testsuite/gcc.target/aarch64/target_attr_18.c
> new file mode 100644
> index 0000000..33b1d44
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/target_attr_18.c
> @@ -0,0 +1,21 @@
> +/* This is a copy of target_attr_6.c to instead check no-strict-align. */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -save-temps -mstrict-align" } */
> +
> +/* Inlining strict-align functions into non-strict align
> + functions is not allowed. */
> +
> +int
> +bar (int a)
> +{
> + return a - 6;
> +}
> +
> +__attribute__ ((target ("no-strict-align")))
> +int
> +bam (int a)
> +{
> + return a - bar (a);
> +}
> +
> +/* { dg-final { scan-assembler "bl.*bar" } } */
>
OK with those changes. As Kyrill said, don't forget the PR number in
the changelog.
R.
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