Peter Bergner <berg...@linux.ibm.com> writes:
> Adding Richard since he's reviewed the generic opaque mode code in
> the past and this patch contains some more eneric support.
>
> GCC handles pseudos that are used uninitialized, by emitting a
> (set (reg: <reg>) CONST0_RTX(regmode)) before their uninitialized
> pseudo usage. Currently, CONST0_RTX(mode) is NULL for opaque modes,
> which leads to an ICE. The solution is to enhance init_emit_once() to
> add initialization of CONST0_RTX for opaque modes using a target hook,
> since CONST0_RTX probably are different for each opaque mode and each
> target. The default hook throws an error to force the target to think
> hard about what their CONST0_RTX values should be for each mode.
Hmm, but it looks like the hook uses const0_rtx, i.e. a const_int,
for something that isn't an integer mode. Also, the unspec for XOmode
isn't a constant in the normal sense (CONSTANT_P).
I think we should either add a new rtx code for constant opaque modes
or make init-regs just emit the clobber for opaque modes (and not emit
the move).
Thanks,
Richard
>
> This passed bootstrap and regtesting on x86_64-linux and powerpc64le-linux
> with no regressions. Ok for mainline?
>
> Peter
>
>
> gcc/
> PR target/98872
> * config/rs6000/mma.md (*movoo): Accept zero constraint.
> (mma_xxsetaccz): Use CONST0_RTX.
> * config/rs6000/predicates.md: Recognize OOmode CONST0_RTX.
> * config/rs6000/rs6000.c (TARGET_OPAQUE_CONST0_RTX): Define.
> (rs6000_split_multireg_move): Handle splitting an OOmode register
> set to CONST0_RTX.
> (rs6000_opaque_const0_rtx): New function.
> * emit-rtl.c (init_emit_once): Initialize CONST0_RTX for opaque modes.
> * hooks.c (hook_rtx_mode_unreachable): New function.
> * hooks.h (hook_rtx_mode_unreachable): Declare
> * target.def (opaque_const0_rtx): New target hook.
> * doc/tm.texi.in: Document it.
> * doc/tm.texi: Regenerate.
>
> gcc/testsuite/
> * gcc.target/powerpc/pr98872.c: New test.
>
> diff --git a/gcc/config/rs6000/mma.md b/gcc/config/rs6000/mma.md
> index 87569f1c31d..fab849a4f12 100644
> --- a/gcc/config/rs6000/mma.md
> +++ b/gcc/config/rs6000/mma.md
> @@ -272,7 +272,7 @@
>
> (define_insn_and_split "*movoo"
> [(set (match_operand:OO 0 "nonimmediate_operand" "=wa,m,wa")
> - (match_operand:OO 1 "input_operand" "m,wa,wa"))]
> + (match_operand:OO 1 "input_operand" "m,wa,waO"))]
> "TARGET_MMA
> && (gpc_reg_operand (operands[0], OOmode)
> || gpc_reg_operand (operands[1], OOmode))"
> @@ -473,9 +473,7 @@
> (const_int 0))]
> "TARGET_MMA"
> {
> - rtx xo0 = gen_rtx_UNSPEC (XOmode, gen_rtvec (1, const0_rtx),
> - UNSPEC_MMA_XXSETACCZ);
> - emit_insn (gen_rtx_SET (operands[0], xo0));
> + emit_insn (gen_rtx_SET (operands[0], CONST0_RTX (XOmode)));
> DONE;
> })
>
> diff --git a/gcc/config/rs6000/predicates.md b/gcc/config/rs6000/predicates.md
> index 5d1952e59d3..30805ab0619 100644
> --- a/gcc/config/rs6000/predicates.md
> +++ b/gcc/config/rs6000/predicates.md
> @@ -1081,6 +1081,10 @@
> && easy_vector_constant (op, mode))
> return 1;
>
> + /* For OOmode, zero is an easy constant. */
> + if (mode == OOmode && op == CONST0_RTX (mode))
> + return 1;
> +
> /* For floating-point or multi-word mode, the only remaining valid type
> is a register. */
> if (SCALAR_FLOAT_MODE_P (mode)
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index f5565a1a253..c726aa09d26 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -1752,6 +1752,10 @@ static const struct attribute_spec
> rs6000_attribute_table[] =
>
> #undef TARGET_INVALID_CONVERSION
> #define TARGET_INVALID_CONVERSION rs6000_invalid_conversion
> +
> +#undef TARGET_OPAQUE_CONST0_RTX
> +#define TARGET_OPAQUE_CONST0_RTX rs6000_opaque_const0_rtx
> +
>
>
> /* Processor table. */
> @@ -16624,6 +16628,19 @@ rs6000_split_multireg_move (rtx dst, rtx src)
> return;
> }
>
> + /* Split the clearing of an OOmode register pair into clearing
> + of its two constituent registers. */
> + if (REG_P (dst) && mode == OOmode && src == CONST0_RTX (mode))
> + {
> + int regno = REGNO (dst);
> + gcc_assert (VSX_REGNO_P (regno));
> + emit_insn (gen_rtx_SET (gen_rtx_REG (reg_mode, regno),
> + CONST0_RTX (reg_mode)));
> + emit_insn (gen_rtx_SET (gen_rtx_REG (reg_mode, regno + 1),
> + CONST0_RTX (reg_mode)));
> + return;
> + }
> +
> /* Register -> register moves can use common code. */
> }
>
> @@ -27477,6 +27494,25 @@ rs6000_output_addr_vec_elt (FILE *file, int value)
> fprintf (file, "\n");
> }
>
> +/* Implement TARGET_OPAQUE_CONST0_RTX. */
> +
> +rtx
> +rs6000_opaque_const0_rtx (machine_mode mode)
> +{
> + gcc_assert (OPAQUE_MODE_P (mode));
> +
> + switch (mode)
> + {
> + case E_OOmode:
> + return const0_rtx;
> + case E_XOmode:
> + return gen_rtx_UNSPEC (XOmode, gen_rtvec (1, const0_rtx),
> + UNSPEC_MMA_XXSETACCZ);
> + default:
> + gcc_unreachable ();
> + }
> +}
> +
> struct gcc_target targetm = TARGET_INITIALIZER;
>
> #include "gt-rs6000.h"
> diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
> index b23284e5e56..4ac26491481 100644
> --- a/gcc/emit-rtl.c
> +++ b/gcc/emit-rtl.c
> @@ -6408,6 +6408,11 @@ init_emit_once (void)
> if (GET_MODE_CLASS ((machine_mode) i) == MODE_CC)
> const_tiny_rtx[0][i] = const0_rtx;
>
> + FOR_EACH_MODE_IN_CLASS (mode, MODE_OPAQUE)
> + {
> + const_tiny_rtx[0][(int) mode] = targetm.opaque_const0_rtx (mode);
> + }
> +
> pc_rtx = gen_rtx_fmt_ (PC, VOIDmode);
> ret_rtx = gen_rtx_fmt_ (RETURN, VOIDmode);
> simple_return_rtx = gen_rtx_fmt_ (SIMPLE_RETURN, VOIDmode);
> diff --git a/gcc/hooks.c b/gcc/hooks.c
> index 680271f76a4..8e71105265a 100644
> --- a/gcc/hooks.c
> +++ b/gcc/hooks.c
> @@ -380,6 +380,12 @@ hook_bool_wint_wint_uint_bool_true (const widest_int &,
> const widest_int &,
> return true;
> }
>
> +rtx
> +hook_rtx_mode_unreachable (machine_mode mode ATTRIBUTE_UNUSED)
> +{
> + gcc_unreachable ();
> +}
> +
> /* Generic hook that takes an rtx and returns it. */
> rtx
> hook_rtx_rtx_identity (rtx x)
> diff --git a/gcc/hooks.h b/gcc/hooks.h
> index add9a742e41..ba9b6d9ff75 100644
> --- a/gcc/hooks.h
> +++ b/gcc/hooks.h
> @@ -119,6 +119,7 @@ extern unsigned int hook_uint_mode_0 (machine_mode);
> extern bool default_can_output_mi_thunk_no_vcall (const_tree, HOST_WIDE_INT,
> HOST_WIDE_INT, const_tree);
>
> +extern rtx hook_rtx_mode_unreachable (machine_mode);
> extern rtx hook_rtx_rtx_identity (rtx);
> extern rtx hook_rtx_rtx_null (rtx);
> extern rtx hook_rtx_tree_int_null (tree, int);
> diff --git a/gcc/target.def b/gcc/target.def
> index be7fcde961a..c026e584c78 100644
> --- a/gcc/target.def
> +++ b/gcc/target.def
> @@ -3362,6 +3362,13 @@ constants can be done inline. The function\n\
> HOST_WIDE_INT, (const_tree constant, HOST_WIDE_INT basic_align),
> default_constant_alignment)
>
> +DEFHOOK
> +(opaque_const0_rtx,
> + "Return an RTX representing the value @code{0} for opaque mode
> @var{mode}.\n\
> +The default version of this hook always throws an error.",
> +rtx, (machine_mode mode),
> +hook_rtx_mode_unreachable)
> +
> DEFHOOK
> (translate_mode_attribute,
> "Define this hook if during mode attribute processing, the port should\n\
> diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
> index 3b19e6f4281..74f6626112b 100644
> --- a/gcc/doc/tm.texi.in
> +++ b/gcc/doc/tm.texi.in
> @@ -3361,6 +3361,8 @@ stack.
>
> @hook TARGET_REF_MAY_ALIAS_ERRNO
>
> +@hook TARGET_OPAQUE_CONST0_RTX
> +
> @hook TARGET_TRANSLATE_MODE_ATTRIBUTE
>
> @hook TARGET_SCALAR_MODE_SUPPORTED_P
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr98872.c
> b/gcc/testsuite/gcc.target/powerpc/pr98872.c
> new file mode 100644
> index 00000000000..580b90de7dc
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr98872.c
> @@ -0,0 +1,20 @@
> +/* PR target/98872 */
> +/* { dg-do compile } */
> +/* { dg-require-effective-target power10_ok } */
> +/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
> +
> +/* Verify we do not ICE on the tests below. */
> +
> +void
> +foo (__vector_quad *dst)
> +{
> + __vector_quad acc;
> + *dst = acc;
> +}
> +
> +void
> +bar (__vector_pair *dst)
> +{
> + __vector_pair pair;
> + *dst = pair;
> +}
