Hi Richard,
seems this still hasn't gone upstream ... Any news?
Thanks,
Ulrich
> This is yet another bug caused by rtx having modeless scalar integer
> constants. We need to use context to find the actual mode of a
> CONST_INT or CONST_WIDE_INT.
>
> Getting a mode is especially awkward here. Decls have two modes
> associated with them: TYPE_MODE (TREE_TYPE (decl)) and DECL_MODE (decl).
> Promotion via things like promote_decl_mode can lead to the rtl having
> a mode that is different from both of them. Sometimes structure decls
> have BLKmode but are assigned an integer-mode rtl (e.g. when passing
> 3-byte structures by value to functions).
>
> I think in this case we're just going to have to assume that none of
> these fancy mode changes happen for something that's big enough to
> need a CONST_WIDE_INT.
>
> loc_descriptor refuses to use CONST_INT for BLKmode decls (which aren't
> actually integers at the source level). That seems like the right
> behaviour, so this patch does that for add_const_value_attribute too.
> It asserts that the mode is otherwise sensible for both CONST_INT
> and CONST_WIDE_INT. Asserting for CONST_INT isn't strictly necessary
> but means that the assumption will get much more coverage than asserting
> only for CONST_WIDE_INT does.
>
> Tested on x86_64-linux-gnu and aarch64-linux-gnu. Also tested against
> the gdb testsuite. OK to install?
>
> Thanks,
> Richard
>
> gcc/
> PR debug/66728
> * dwarf2out.c (loc_descriptor): Remove redundant GET_MODE of
> CONST_WIDE_INTs. Handle BLKmode for CONST_WIDE_INT too.
> (add_const_value_attribute): Add a mode parameter.
> Check it for CONST_INT and CONST_WIDE_INT. Use it to build
> wide_int values.
> (add_location_or_const_value_attribute): Update call.
> (tree_add_const_value_attribute): Likewise.
>
> gcc/testsuite/
> PR debug/66728
> * gcc.dg/debug/dwarf2/pr66728.c: New test.
>
> diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
> index d9d3063..383d705 100644
> --- a/gcc/dwarf2out.c
> +++ b/gcc/dwarf2out.c
> @@ -3259,7 +3259,7 @@ static HOST_WIDE_INT field_byte_offset (const_tree);
> static void add_AT_location_description (dw_die_ref, enum
> dwarf_attribute,
> dw_loc_list_ref);
> static void add_data_member_location_attribute (dw_die_ref, tree);
> -static bool add_const_value_attribute (dw_die_ref, rtx);
> +static bool add_const_value_attribute (dw_die_ref, machine_mode, rtx);
> static void insert_int (HOST_WIDE_INT, unsigned, unsigned char *);
> static void insert_wide_int (const wide_int &, unsigned char *, int);
> static void insert_float (const_rtx, unsigned char *);
> @@ -13795,10 +13795,9 @@ loc_descriptor (rtx rtl, machine_mode mode,
> break;
> =20
> case CONST_WIDE_INT:
> - if (mode =3D=3D VOIDmode)
> - mode =3D GET_MODE (rtl);
> -
> - if (mode !=3D VOIDmode && (dwarf_version >=3D 4 || !dwarf_strict))
> + if (mode !=3D VOIDmode
> + && mode !=3D BLKmode
> + && (dwarf_version >=3D 4 || !dwarf_strict))
> {
> loc_result =3D new_loc_descr (DW_OP_implicit_value,
> GET_MODE_SIZE (mode), 0);
> @@ -15576,25 +15575,33 @@ insert_float (const_rtx rtl, unsigned char *array)
> constants do not necessarily get memory "homes". */
> =20
> static bool
> -add_const_value_attribute (dw_die_ref die, rtx rtl)
> +add_const_value_attribute (dw_die_ref die, machine_mode mode, rtx rtl)
> {
> switch (GET_CODE (rtl))
> {
> case CONST_INT:
> - {
> - HOST_WIDE_INT val =3D INTVAL (rtl);
> + if (mode !=3D BLKmode)
> + {
> + gcc_checking_assert (SCALAR_INT_MODE_P (mode));
> + HOST_WIDE_INT val =3D INTVAL (rtl);
> =20
> - if (val < 0)
> - add_AT_int (die, DW_AT_const_value, val);
> - else
> - add_AT_unsigned (die, DW_AT_const_value, (unsigned HOST_WIDE_INT)
> val);
> - }
> - return true;
> + if (val < 0)
> + add_AT_int (die, DW_AT_const_value, val);
> + else
> + add_AT_unsigned (die, DW_AT_const_value,
> + (unsigned HOST_WIDE_INT) val);
> + return true;
> + }
> + return false;
> =20
> case CONST_WIDE_INT:
> - add_AT_wide (die, DW_AT_const_value,
> - std::make_pair (rtl, GET_MODE (rtl)));
> - return true;
> + if (mode !=3D BLKmode)
> + {
> + gcc_checking_assert (SCALAR_INT_MODE_P (mode));
> + add_AT_wide (die, DW_AT_const_value, std::make_pair (rtl, mode));
> + return true;
> + }
> + return false;
> =20
> case CONST_DOUBLE:
> /* Note that a CONST_DOUBLE rtx could represent either an integer or=
> a
> @@ -15671,7 +15678,7 @@ add_const_value_attribute (dw_die_ref die, rtx rtl)
> =20
> case CONST:
> if (CONSTANT_P (XEXP (rtl, 0)))
> - return add_const_value_attribute (die, XEXP (rtl, 0));
> + return add_const_value_attribute (die, mode, XEXP (rtl, 0));
> /* FALLTHROUGH */
> case SYMBOL_REF:
> if (!const_ok_for_output (rtl))
> @@ -16171,7 +16178,7 @@ add_location_or_const_value_attribute (dw_die_ref d=
> ie, tree decl, bool cache_p,
> =20
> rtl =3D rtl_for_decl_location (decl);
> if (rtl && (CONSTANT_P (rtl) || GET_CODE (rtl) =3D=3D CONST_STRING)
> - && add_const_value_attribute (die, rtl))
> + && add_const_value_attribute (die, DECL_MODE (decl), rtl))
> return true;
> =20
> /* See if we have single element location list that is equivalent to
> @@ -16192,7 +16199,7 @@ add_location_or_const_value_attribute (dw_die_ref d=
> ie, tree decl, bool cache_p,
> if (GET_CODE (rtl) =3D=3D EXPR_LIST)
> rtl =3D XEXP (rtl, 0);
> if ((CONSTANT_P (rtl) || GET_CODE (rtl) =3D=3D CONST_STRING)
> - && add_const_value_attribute (die, rtl))
> + && add_const_value_attribute (die, DECL_MODE (decl), rtl))
> return true;
> }
> /* If this decl is from BLOCK_NONLOCALIZED_VARS, we might need its
> @@ -16395,7 +16402,7 @@ tree_add_const_value_attribute (dw_die_ref die, tre=
> e t)
> =20
> rtl =3D rtl_for_decl_init (init, type);
> if (rtl)
> - return add_const_value_attribute (die, rtl);
> + return add_const_value_attribute (die, TYPE_MODE (type), rtl);
> /* If the host and target are sane, try harder. */
> else if (CHAR_BIT =3D=3D 8 && BITS_PER_UNIT =3D=3D 8
> && initializer_constant_valid_p (init, type))
> diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/pr66728.c b/gcc/testsuite/gc=
> c.dg/debug/dwarf2/pr66728.c
> new file mode 100644
> index 0000000..ba41e97
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/debug/dwarf2/pr66728.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile { target { x86_64-*-* && lp64 } } } */
> +/* { dg-options "-O -gdwarf -dA" } */
> +
> +__uint128_t
> +test (void)
> +{
> + static const __uint128_t foo =3D ((((__uint128_t) 0x22334455) << 96)
> + | 0x99aabb);
> +
> + return foo;
> +}
> +
> +/* { dg-final { scan-assembler {\.quad\t0x99aabb\t# DW_AT_const_value} } }=
> */
> +/* { dg-final { scan-assembler {\.quad\t0x2233445500000000\t} } } */
>
--
Dr. Ulrich Weigand
GNU/Linux compilers and toolchain
ulrich.weig...@de.ibm.com
