On Tue, 5 Mar 2024, Jakub Jelinek wrote:
> Hi!
>
> The following patch adds support for BIT_FIELD_REF lowering with
> large/huge _BitInt lhs. BIT_FIELD_REF requires mode argument first
> operand, so the operand shouldn't be any huge _BitInt.
> If we only access limbs from inside of BIT_FIELD_REF using constant
> indexes, we can just create a new BIT_FIELD_REF to extract the limb,
> but if we need to use variable index in a loop, I'm afraid we need
> to spill it into memory, which is what the following patch does.
:/
If it's only ever "small" _BitInt and we'd want to optimize we could
fully unroll the loop at code generation time and thus avoid the
variable indices? You could also lower the BIT_FIELD_REF to
variable shifts & masking I suppose.
Not sure if it's worth the trouble though.
> If there is some bitwise type for the extraction, it extracts just
> what we need and not more than that, otherwise it spills the whole
> first argument of BIT_FIELD_REF and uses MEM_REF with an offset
> with VIEW_CONVERT_EXPR around it.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Thanks,
Richard.
> 2024-03-05 Jakub Jelinek <ja...@redhat.com>
>
> PR middle-end/114157
> * gimple-lower-bitint.cc: Include stor-layout.h.
> (mergeable_op): Return true for BIT_FIELD_REF.
> (struct bitint_large_huge): Declare handle_bit_field_ref method.
> (bitint_large_huge::handle_bit_field_ref): New method.
> (bitint_large_huge::handle_stmt): Use it for BIT_FIELD_REF.
>
> * gcc.dg/bitint-98.c: New test.
> * gcc.target/i386/avx2-pr114157.c: New test.
> * gcc.target/i386/avx512f-pr114157.c: New test.
>
> --- gcc/gimple-lower-bitint.cc.jj 2024-03-04 11:14:57.450288563 +0100
> +++ gcc/gimple-lower-bitint.cc 2024-03-04 18:51:06.833008534 +0100
> @@ -54,6 +54,7 @@ along with GCC; see the file COPYING3.
> #include "tree-cfgcleanup.h"
> #include "tree-switch-conversion.h"
> #include "ubsan.h"
> +#include "stor-layout.h"
> #include "gimple-lower-bitint.h"
>
> /* Split BITINT_TYPE precisions in 4 categories. Small _BitInt, where
> @@ -212,6 +213,7 @@ mergeable_op (gimple *stmt)
> case BIT_NOT_EXPR:
> case SSA_NAME:
> case INTEGER_CST:
> + case BIT_FIELD_REF:
> return true;
> case LSHIFT_EXPR:
> {
> @@ -435,6 +437,7 @@ struct bitint_large_huge
> tree handle_plus_minus (tree_code, tree, tree, tree);
> tree handle_lshift (tree, tree, tree);
> tree handle_cast (tree, tree, tree);
> + tree handle_bit_field_ref (tree, tree);
> tree handle_load (gimple *, tree);
> tree handle_stmt (gimple *, tree);
> tree handle_operand_addr (tree, gimple *, int *, int *);
> @@ -1685,6 +1688,86 @@ bitint_large_huge::handle_cast (tree lhs
> return NULL_TREE;
> }
>
> +/* Helper function for handle_stmt method, handle a BIT_FIELD_REF. */
> +
> +tree
> +bitint_large_huge::handle_bit_field_ref (tree op, tree idx)
> +{
> + if (tree_fits_uhwi_p (idx))
> + {
> + if (m_first)
> + m_data.safe_push (NULL);
> + ++m_data_cnt;
> + unsigned HOST_WIDE_INT sz = tree_to_uhwi (TYPE_SIZE (m_limb_type));
> + tree bfr = build3 (BIT_FIELD_REF, m_limb_type,
> + TREE_OPERAND (op, 0),
> + TYPE_SIZE (m_limb_type),
> + size_binop (PLUS_EXPR, TREE_OPERAND (op, 2),
> + bitsize_int (tree_to_uhwi (idx) * sz)));
> + tree r = make_ssa_name (m_limb_type);
> + gimple *g = gimple_build_assign (r, bfr);
> + insert_before (g);
> + tree type = limb_access_type (TREE_TYPE (op), idx);
> + if (!useless_type_conversion_p (type, m_limb_type))
> + r = add_cast (type, r);
> + return r;
> + }
> + tree var;
> + if (m_first)
> + {
> + unsigned HOST_WIDE_INT sz = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (op)));
> + machine_mode mode;
> + tree type, bfr;
> + if (bitwise_mode_for_size (sz).exists (&mode)
> + && known_eq (GET_MODE_BITSIZE (mode), sz))
> + type = bitwise_type_for_mode (mode);
> + else
> + {
> + mode = VOIDmode;
> + type = TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (op, 0)));
> + }
> + if (TYPE_ALIGN (type) < TYPE_ALIGN (TREE_TYPE (op)))
> + type = build_aligned_type (type, TYPE_ALIGN (TREE_TYPE (op)));
> + var = create_tmp_var (type);
> + TREE_ADDRESSABLE (var) = 1;
> + gimple *g;
> + if (mode != VOIDmode)
> + {
> + bfr = build3 (BIT_FIELD_REF, type, TREE_OPERAND (op, 0),
> + TYPE_SIZE (type), TREE_OPERAND (op, 2));
> + g = gimple_build_assign (make_ssa_name (type),
> + BIT_FIELD_REF, bfr);
> + gimple_set_location (g, m_loc);
> + gsi_insert_after (&m_init_gsi, g, GSI_NEW_STMT);
> + bfr = gimple_assign_lhs (g);
> + }
> + else
> + bfr = TREE_OPERAND (op, 0);
> + g = gimple_build_assign (var, bfr);
> + gimple_set_location (g, m_loc);
> + gsi_insert_after (&m_init_gsi, g, GSI_NEW_STMT);
> + if (mode == VOIDmode)
> + {
> + unsigned HOST_WIDE_INT nelts
> + = CEIL (tree_to_uhwi (TYPE_SIZE (TREE_TYPE (op))), limb_prec);
> + tree atype = build_array_type_nelts (m_limb_type, nelts);
> + var = build2 (MEM_REF, atype, build_fold_addr_expr (var),
> + build_int_cst (build_pointer_type (type),
> + tree_to_uhwi (TREE_OPERAND (op, 2))
> + / BITS_PER_UNIT));
> + }
> + m_data.safe_push (var);
> + }
> + else
> + var = unshare_expr (m_data[m_data_cnt]);
> + ++m_data_cnt;
> + var = limb_access (TREE_TYPE (op), var, idx, false);
> + tree r = make_ssa_name (m_limb_type);
> + gimple *g = gimple_build_assign (r, var);
> + insert_before (g);
> + return r;
> +}
> +
> /* Add a new EH edge from SRC to EH_EDGE->dest, where EH_EDGE
> is an older EH edge, and except for virtual PHIs duplicate the
> PHI argument from the EH_EDGE to the new EH edge. */
> @@ -2019,6 +2102,8 @@ bitint_large_huge::handle_stmt (gimple *
> return handle_cast (TREE_TYPE (gimple_assign_lhs (stmt)),
> TREE_OPERAND (gimple_assign_rhs1 (stmt), 0),
> idx);
> + case BIT_FIELD_REF:
> + return handle_bit_field_ref (gimple_assign_rhs1 (stmt), idx);
> default:
> break;
> }
> --- gcc/testsuite/gcc.dg/bitint-98.c.jj 2024-03-04 19:11:46.355244244
> +0100
> +++ gcc/testsuite/gcc.dg/bitint-98.c 2024-03-04 19:10:35.139207685 +0100
> @@ -0,0 +1,50 @@
> +/* PR middle-end/114157 */
> +/* { dg-do compile { target bitint } } */
> +/* { dg-options "-O2 -std=c23 -Wno-psabi -w" } */
> +
> +#if __BITINT_MAXWIDTH__ >= 256
> +_BitInt(256) d;
> +_BitInt(255) e;
> +
> +void
> +foo (long __attribute__((vector_size (64))) s)
> +{
> + __builtin_memmove (&d, &s, sizeof (d));
> +}
> +
> +void
> +bar (_BitInt(512) x)
> +{
> + long __attribute__((vector_size (64))) s;
> + __builtin_memcpy (&s, &x, sizeof (s));
> + __builtin_memcpy (&d, &s, sizeof (d));
> +}
> +
> +void
> +baz (long __attribute__((vector_size (64))) s)
> +{
> + _BitInt(256) d;
> + __builtin_memmove (&d, &s, sizeof (d));
> + e = d;
> +}
> +
> +void
> +qux (long __attribute__((vector_size (64))) s)
> +{
> + _BitInt(192) d;
> + __builtin_memmove (&d, &s, sizeof (d));
> + e = d;
> +}
> +#else
> +int i;
> +#endif
> +
> +#if __BITINT_MAXWIDTH__ >= 1024
> +_BitInt(512)
> +corge (long __attribute__((vector_size (1024))) s)
> +{
> + _BitInt(512) d;
> + __builtin_memcpy (&d, &s, sizeof (d));
> + return d;
> +}
> +#endif
> --- gcc/testsuite/gcc.target/i386/avx2-pr114157.c.jj 2024-03-04
> 19:12:46.001437331 +0100
> +++ gcc/testsuite/gcc.target/i386/avx2-pr114157.c 2024-03-04
> 19:12:31.639631618 +0100
> @@ -0,0 +1,5 @@
> +/* PR middle-end/114157 */
> +/* { dg-do compile { target bitint } } */
> +/* { dg-options "-O2 -std=c23 -Wno-psabi -w -mavx2 -mno-avx512f" } */
> +
> +#include "../../gcc.dg/bitint-98.c"
> --- gcc/testsuite/gcc.target/i386/avx512f-pr114157.c.jj 2024-03-04
> 19:13:01.190231847 +0100
> +++ gcc/testsuite/gcc.target/i386/avx512f-pr114157.c 2024-03-04
> 19:13:12.018085362 +0100
> @@ -0,0 +1,5 @@
> +/* PR middle-end/114157 */
> +/* { dg-do compile { target bitint } } */
> +/* { dg-options "-O2 -std=c23 -Wno-psabi -w -mavx512f" } */
> +
> +#include "../../gcc.dg/bitint-98.c"
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
