RE: [GCC-10 backport][PATCH] arm: _Generic feature failing with ICE for -O0 (pr97205).

[Srinath Parvathaneni via Gcc-patches]

Ping!!

> -----Original Message-----
> From: Srinath Parvathaneni <srinath.parvathan...@arm.com>
> Sent: 30 April 2021 16:24
> To: gcc-patches@gcc.gnu.org
> Cc: Kyrylo Tkachov <kyrylo.tkac...@arm.com>; Richard Earnshaw
> <richard.earns...@arm.com>
> Subject: [GCC-10 backport][PATCH] arm: _Generic feature failing with ICE for
> -O0 (pr97205).
> 
> Hi,
> 
> This is a backport to GCC-10 to fix PR97205, patch applies cleanly on the
> branch.
> 
> Regression tested and found no issues.
> 
> Ok for GCC-10 backport?
> 
> Regards,
> Srinath.
> 
>     This makes sure that stack allocated SSA_NAMEs are
>     at least MODE_ALIGNED.  Also increase the MEM_ALIGN
>     for the corresponding rtl objects.
> 
>     gcc:
>     2020-11-03  Bernd Edlinger  <bernd.edlin...@hotmail.de>
> 
>         PR target/97205
>         * cfgexpand.c (align_local_variable): Make SSA_NAMEs
>         at least MODE_ALIGNED.
>         (expand_one_stack_var_at): Increase MEM_ALIGN for SSA_NAMEs.
> 
>     gcc/testsuite:
>     2020-11-03  Bernd Edlinger  <bernd.edlin...@hotmail.de>
> 
>         PR target/97205
>         * gcc.c-torture/compile/pr97205.c: New test.
> 
>     (cherry picked from commit
> 23ac7a009ecfeec3eab79136abed8aac9768b458)
> 
> 
> ###############     Attachment also inlined for ease of reply
> ###############
> 
> 
> diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c index
> bf4f194ed993134109cc21be9cb0ed8a5c170824..4fef5d6ebf420ce4d6f59606e
> cd064f45ae59065 100644
> --- a/gcc/cfgexpand.c
> +++ b/gcc/cfgexpand.c
> @@ -366,7 +366,15 @@ align_local_variable (tree decl, bool really_expand)
>    unsigned int align;
> 
>    if (TREE_CODE (decl) == SSA_NAME)
> -    align = TYPE_ALIGN (TREE_TYPE (decl));
> +    {
> +      tree type = TREE_TYPE (decl);
> +      machine_mode mode = TYPE_MODE (type);
> +
> +      align = TYPE_ALIGN (type);
> +      if (mode != BLKmode
> +       && align < GET_MODE_ALIGNMENT (mode))
> +     align = GET_MODE_ALIGNMENT (mode);
> +    }
>    else
>      {
>        align = LOCAL_DECL_ALIGNMENT (decl); @@ -999,20 +1007,21 @@
> expand_one_stack_var_at (tree decl, rtx base, unsigned base_align,
>    x = plus_constant (Pmode, base, offset);
>    x = gen_rtx_MEM (TREE_CODE (decl) == SSA_NAME
>                  ? TYPE_MODE (TREE_TYPE (decl))
> -                : DECL_MODE (SSAVAR (decl)), x);
> +                : DECL_MODE (decl), x);
> +
> +  /* Set alignment we actually gave this decl if it isn't an SSA name.
> +     If it is we generate stack slots only accidentally so it isn't as
> +     important, we'll simply set the alignment directly on the MEM.  */
> +
> +  if (base == virtual_stack_vars_rtx)
> +    offset -= frame_phase;
> +  align = known_alignment (offset);
> +  align *= BITS_PER_UNIT;
> +  if (align == 0 || align > base_align)
> +    align = base_align;
> 
>    if (TREE_CODE (decl) != SSA_NAME)
>      {
> -      /* Set alignment we actually gave this decl if it isn't an SSA name.
> -         If it is we generate stack slots only accidentally so it isn't as
> -      important, we'll simply use the alignment that is already set.  */
> -      if (base == virtual_stack_vars_rtx)
> -     offset -= frame_phase;
> -      align = known_alignment (offset);
> -      align *= BITS_PER_UNIT;
> -      if (align == 0 || align > base_align)
> -     align = base_align;
> -
>        /* One would think that we could assert that we're not decreasing
>        alignment here, but (at least) the i386 port does exactly this
>        via the MINIMUM_ALIGNMENT hook.  */
> @@ -1022,6 +1031,8 @@ expand_one_stack_var_at (tree decl, rtx base,
> unsigned base_align,
>      }
> 
>    set_rtl (decl, x);
> +
> +  set_mem_align (x, align);
>  }
> 
>  class stack_vars_data
> @@ -1327,13 +1338,11 @@ expand_one_stack_var_1 (tree var)
>      {
>        tree type = TREE_TYPE (var);
>        size = tree_to_poly_uint64 (TYPE_SIZE_UNIT (type));
> -      byte_align = TYPE_ALIGN_UNIT (type);
>      }
>    else
> -    {
> -      size = tree_to_poly_uint64 (DECL_SIZE_UNIT (var));
> -      byte_align = align_local_variable (var, true);
> -    }
> +    size = tree_to_poly_uint64 (DECL_SIZE_UNIT (var));
> +
> +  byte_align = align_local_variable (var, true);
> 
>    /* We handle highly aligned variables in expand_stack_vars.  */
>    gcc_assert (byte_align * BITS_PER_UNIT <=
> MAX_SUPPORTED_STACK_ALIGNMENT); diff --git a/gcc/testsuite/gcc.c-
> torture/compile/pr97205.c b/gcc/testsuite/gcc.c-torture/compile/pr97205.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..6600011fcf84660edcba8d9
> 68c78ee6aaa0aa923
> --- /dev/null
> +++ b/gcc/testsuite/gcc.c-torture/compile/pr97205.c
> @@ -0,0 +1,7 @@
> +int a;
> +typedef __attribute__((aligned(2))) int x; int f () {
> +  x b = a;
> +  return b;
> +}