[PATCH][RFC] Introduce BIT_FIELD_INSERT
Richard Biener
rguenther@suse.de
Thu Nov 15 08:29:00 GMT 2018
On Wed, 14 Nov 2018, Andrew Pinski wrote:
> On Fri, May 13, 2016 at 3:51 AM Richard Biener <rguenther@suse.de> wrote:
> >
> >
> > The following patch adds BIT_FIELD_INSERT, an operation to
> > facilitate doing bitfield inserts on registers (as opposed
> > to currently where we'd have a BIT_FIELD_REF store).
> >
> > Originally this was developed as part of bitfield lowering
> > where bitfield stores were lowered into read-modify-write
> > cycles and the modify part, instead of doing shifting and masking,
> > be kept in a more high-level form to ease combining them.
> >
> > A second use case (the above is still valid) is vector element
> > inserts which we currently can only do via memory or
> > by extracting all components and re-building the vector using
> > a CONSTRUCTOR. For this second use case I added code
> > re-writing the BIT_FIELD_REF stores the C family FEs produce
> > into BIT_FIELD_INSERT when update-address-taken can otherwise
> > re-write a decl into SSA form (the testcase shows we miss
> > a similar opportunity with the MEM_REF form of a vector insert,
> > I plan to fix that for the final submission).
> >
> > One speciality of BIT_FIELD_INSERT as opposed to BIT_FIELD_REF
> > is that the size of the insertion is given implicitely via the
> > type size/precision of the value to insert. That avoids
> > introducing ways to have quaternary ops in folding and GIMPLE stmts.
> >
> > Bootstrapped and tested on x86_64-unknown-linux-gnu.
> >
> > Richard.
> >
> > 2011-06-16 Richard Guenther <rguenther@suse.de>
> >
> > PR tree-optimization/29756
> > * tree.def (BIT_FIELD_INSERT): New tcc_expression tree code.
> > * expr.c (expand_expr_real_2): Handle BIT_FIELD_INSERT.
> > * fold-const.c (operand_equal_p): Likewise.
> > (fold_ternary_loc): Add constant folding of BIT_FIELD_INSERT.
> > * gimplify.c (gimplify_expr): Handle BIT_FIELD_INSERT.
> > * tree-inline.c (estimate_operator_cost): Likewise.
> > * tree-pretty-print.c (dump_generic_node): Likewise.
> > * tree-ssa-operands.c (get_expr_operands): Likewise.
> > * cfgexpand.c (expand_debug_expr): Likewise.
> > * gimple-pretty-print.c (dump_ternary_rhs): Likewise.
> > * gimple.c (get_gimple_rhs_num_ops): Handle BIT_FIELD_INSERT.
> > * tree-cfg.c (verify_gimple_assign_ternary): Verify BIT_FIELD_INSERT.
> >
> > * tree-ssa.c (non_rewritable_lvalue_p): We can rewrite
> > vector inserts using BIT_FIELD_REF on the lhs.
> > (execute_update_addresses_taken): Do it.
> >
> > * gcc.dg/tree-ssa/vector-6.c: New testcase.
> >
> > Index: trunk/gcc/expr.c
> > ===================================================================
> > *** trunk.orig/gcc/expr.c 2016-05-12 13:40:30.704262951 +0200
> > --- trunk/gcc/expr.c 2016-05-12 15:40:32.481225744 +0200
> > *************** expand_expr_real_2 (sepops ops, rtx targ
> > *** 9358,9363 ****
> > --- 9358,9380 ----
> > target = expand_vec_cond_expr (type, treeop0, treeop1, treeop2, target);
> > return target;
> >
> > + case BIT_FIELD_INSERT:
> > + {
> > + unsigned bitpos = tree_to_uhwi (treeop2);
> > + unsigned bitsize;
> > + if (INTEGRAL_TYPE_P (TREE_TYPE (treeop1)))
> > + bitsize = TYPE_PRECISION (TREE_TYPE (treeop1));
> > + else
> > + bitsize = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (treeop1)));
> > + rtx op0 = expand_normal (treeop0);
> > + rtx op1 = expand_normal (treeop1);
> > + rtx dst = gen_reg_rtx (mode);
> > + emit_move_insn (dst, op0);
> > + store_bit_field (dst, bitsize, bitpos, 0, 0,
> > + TYPE_MODE (TREE_TYPE (treeop1)), op1, false);
> > + return dst;
> > + }
> > +
> > default:
> > gcc_unreachable ();
> > }
> > Index: trunk/gcc/fold-const.c
> > ===================================================================
> > *** trunk.orig/gcc/fold-const.c 2016-05-12 13:40:30.704262951 +0200
> > --- trunk/gcc/fold-const.c 2016-05-13 09:41:13.509812127 +0200
> > *************** operand_equal_p (const_tree arg0, const_
> > *** 3163,3168 ****
> > --- 3163,3169 ----
> >
> > case VEC_COND_EXPR:
> > case DOT_PROD_EXPR:
> > + case BIT_FIELD_INSERT:
> > return OP_SAME (0) && OP_SAME (1) && OP_SAME (2);
> >
> > default:
> > *************** fold_ternary_loc (location_t loc, enum t
> > *** 11870,11875 ****
> > --- 11871,11916 ----
> > }
> > return NULL_TREE;
> >
> > + case BIT_FIELD_INSERT:
> > + /* Perform (partial) constant folding of BIT_FIELD_INSERT. */
> > + if (TREE_CODE (arg0) == INTEGER_CST
> > + && TREE_CODE (arg1) == INTEGER_CST)
> > + {
> > + unsigned HOST_WIDE_INT bitpos = tree_to_uhwi (op2);
> > + unsigned bitsize = TYPE_PRECISION (TREE_TYPE (arg1));
> > + wide_int tem = wi::bit_and (arg0,
> > + wi::shifted_mask (bitpos, bitsize, true,
> > + TYPE_PRECISION (type)));
> > + wide_int tem2
> > + = wi::lshift (wi::zext (wi::to_wide (arg1, TYPE_PRECISION (type)),
> > + bitsize), bitpos);
> > + return wide_int_to_tree (type, wi::bit_or (tem, tem2));
> > + }
>
> This seems incorrect for the case where BYTES_BIG_ENDIAN as far as I
> can tell. With BYTES_BIG_ENDIAN, the bits position starts most
> significiant rather than the least significiant.
You mean the bitpos operand of BIT_FIELD_INSERT works in a different way?
I see the BIT_FIELD_REF folding uses native_encode/interpret but only
handles byte-aligned references. I suppose the BIT_INSERT_EXPR case
(you are following up an old patch) could do the same.
> Sorry I am bring
> this up after this has been in the tree for a long time but I finally
> got around to testing my bit-field lowering on a few big-endian
> targets and ran into this issue.
So - can you fix it please? Also note that the VECTOR_CST case
(as in BIT_FIELD_REF) seems to be inconsistent here and counts
"bits" in a different way?
Thanks,
Richard.
> Thanks,
> Andrew Pinski
>
> > + else if (TREE_CODE (arg0) == VECTOR_CST
> > + && CONSTANT_CLASS_P (arg1)
> > + && types_compatible_p (TREE_TYPE (TREE_TYPE (arg0)),
> > + TREE_TYPE (arg1)))
> > + {
> > + unsigned HOST_WIDE_INT bitpos = tree_to_uhwi (op2);
> > + unsigned HOST_WIDE_INT elsize
> > + = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (arg1)));
> > + if (bitpos % elsize == 0)
> > + {
> > + unsigned k = bitpos / elsize;
> > + if (operand_equal_p (VECTOR_CST_ELT (arg0, k), arg1, 0))
> > + return arg0;
> > + else
> > + {
> > + tree *elts = XALLOCAVEC (tree, TYPE_VECTOR_SUBPARTS (type));
> > + memcpy (elts, VECTOR_CST_ELTS (arg0),
> > + sizeof (tree) * TYPE_VECTOR_SUBPARTS (type));
> > + elts[k] = arg1;
> > + return build_vector (type, elts);
> > + }
> > + }
> > + }
> > + return NULL_TREE;
> > +
> > default:
> > return NULL_TREE;
> > } /* switch (code) */
> > Index: trunk/gcc/gimplify.c
> > ===================================================================
> > *** trunk.orig/gcc/gimplify.c 2016-05-12 13:40:30.704262951 +0200
> > --- trunk/gcc/gimplify.c 2016-05-12 13:56:18.679120641 +0200
> > *************** gimplify_expr (tree *expr_p, gimple_seq
> > *** 10936,10941 ****
> > --- 10936,10945 ----
> > /* Classified as tcc_expression. */
> > goto expr_3;
> >
> > + case BIT_FIELD_INSERT:
> > + /* Argument 3 is a constant. */
> > + goto expr_2;
> > +
> > case POINTER_PLUS_EXPR:
> > {
> > enum gimplify_status r0, r1;
> > Index: trunk/gcc/tree-inline.c
> > ===================================================================
> > *** trunk.orig/gcc/tree-inline.c 2016-05-12 13:40:30.704262951 +0200
> > --- trunk/gcc/tree-inline.c 2016-05-12 13:42:45.465811959 +0200
> > *************** estimate_operator_cost (enum tree_code c
> > *** 3941,3946 ****
> > --- 3941,3950 ----
> > return weights->div_mod_cost;
> > return 1;
> >
> > + /* Bit-field insertion needs several shift and mask operations. */
> > + case BIT_FIELD_INSERT:
> > + return 3;
> > +
> > default:
> > /* We expect a copy assignment with no operator. */
> > gcc_assert (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS);
> > Index: trunk/gcc/tree-pretty-print.c
> > ===================================================================
> > *** trunk.orig/gcc/tree-pretty-print.c 2016-05-12 13:40:30.704262951 +0200
> > --- trunk/gcc/tree-pretty-print.c 2016-05-12 14:30:05.781944740 +0200
> > *************** dump_generic_node (pretty_printer *pp, t
> > *** 1876,1881 ****
> > --- 1876,1898 ----
> > pp_greater (pp);
> > break;
> >
> > + case BIT_FIELD_INSERT:
> > + pp_string (pp, "BIT_FIELD_INSERT <");
> > + dump_generic_node (pp, TREE_OPERAND (node, 0), spc, flags, false);
> > + pp_string (pp, ", ");
> > + dump_generic_node (pp, TREE_OPERAND (node, 1), spc, flags, false);
> > + pp_string (pp, ", ");
> > + dump_generic_node (pp, TREE_OPERAND (node, 2), spc, flags, false);
> > + pp_string (pp, " (");
> > + if (INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (node, 1))))
> > + pp_decimal_int (pp,
> > + TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (node, 1))));
> > + else
> > + dump_generic_node (pp, TYPE_SIZE (TREE_TYPE (TREE_OPERAND (node, 1))),
> > + spc, flags, false);
> > + pp_string (pp, " bits)>");
> > + break;
> > +
> > case ARRAY_REF:
> > case ARRAY_RANGE_REF:
> > op0 = TREE_OPERAND (node, 0);
> > Index: trunk/gcc/tree-ssa-operands.c
> > ===================================================================
> > *** trunk.orig/gcc/tree-ssa-operands.c 2016-05-12 13:42:45.465811959 +0200
> > --- trunk/gcc/tree-ssa-operands.c 2016-05-12 13:48:26.881736503 +0200
> > *************** get_expr_operands (struct function *fn,
> > *** 833,838 ****
> > --- 833,839 ----
> > get_expr_operands (fn, stmt, &TREE_OPERAND (expr, 0), flags);
> > return;
> >
> > + case BIT_FIELD_INSERT:
> > case COMPOUND_EXPR:
> > case OBJ_TYPE_REF:
> > case ASSERT_EXPR:
> > Index: trunk/gcc/tree.def
> > ===================================================================
> > *** trunk.orig/gcc/tree.def 2016-05-12 13:40:30.704262951 +0200
> > --- trunk/gcc/tree.def 2016-05-12 13:47:09.972852423 +0200
> > *************** DEFTREECODE (ADDR_EXPR, "addr_expr", tcc
> > *** 852,857 ****
> > --- 852,868 ----
> > descriptor of type ptr_mode. */
> > DEFTREECODE (FDESC_EXPR, "fdesc_expr", tcc_expression, 2)
> >
> > + /* Given a word, a value and a bitfield position within the word,
> > + produce the value that results if replacing the
> > + described parts of word with value.
> > + Operand 0 is a tree for the word of integral type;
> > + Operand 1 is a tree for the value of integral type;
> > + Operand 2 is a tree giving the constant position of the first referenced bit;
> > + The number of bits replaced is given by the precision of the value
> > + type if that is integral or by its size if it is non-integral.
> > + The replaced bits shall be fully inside the word. */
> > + DEFTREECODE (BIT_FIELD_INSERT, "bit_field_insert", tcc_expression, 3)
> > +
> > /* Given two real or integer operands of the same type,
> > returns a complex value of the corresponding complex type. */
> > DEFTREECODE (COMPLEX_EXPR, "complex_expr", tcc_binary, 2)
> > Index: trunk/gcc/cfgexpand.c
> > ===================================================================
> > *** trunk.orig/gcc/cfgexpand.c 2016-05-12 13:42:45.469812005 +0200
> > --- trunk/gcc/cfgexpand.c 2016-05-13 11:48:04.513407495 +0200
> > *************** expand_debug_expr (tree exp)
> > *** 5025,5030 ****
> > --- 5025,5031 ----
> > case FIXED_CONVERT_EXPR:
> > case OBJ_TYPE_REF:
> > case WITH_SIZE_EXPR:
> > + case BIT_FIELD_INSERT:
> > return NULL;
> >
> > case DOT_PROD_EXPR:
> > Index: trunk/gcc/gimple-pretty-print.c
> > ===================================================================
> > *** trunk.orig/gcc/gimple-pretty-print.c 2016-05-12 11:23:09.261375157 +0200
> > --- trunk/gcc/gimple-pretty-print.c 2016-05-12 14:57:22.096175579 +0200
> > *************** dump_ternary_rhs (pretty_printer *buffer
> > *** 479,484 ****
> > --- 479,502 ----
> > pp_greater (buffer);
> > break;
> >
> > + case BIT_FIELD_INSERT:
> > + pp_string (buffer, "BIT_FIELD_INSERT <");
> > + dump_generic_node (buffer, gimple_assign_rhs1 (gs), spc, flags, false);
> > + pp_string (buffer, ", ");
> > + dump_generic_node (buffer, gimple_assign_rhs2 (gs), spc, flags, false);
> > + pp_string (buffer, ", ");
> > + dump_generic_node (buffer, gimple_assign_rhs3 (gs), spc, flags, false);
> > + pp_string (buffer, " (");
> > + if (INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_rhs2 (gs))))
> > + pp_decimal_int (buffer,
> > + TYPE_PRECISION (TREE_TYPE (gimple_assign_rhs2 (gs))));
> > + else
> > + dump_generic_node (buffer,
> > + TYPE_SIZE (TREE_TYPE (gimple_assign_rhs2 (gs))),
> > + spc, flags, false);
> > + pp_string (buffer, " bits)>");
> > + break;
> > +
> > default:
> > gcc_unreachable ();
> > }
> > Index: trunk/gcc/gimple.c
> > ===================================================================
> > *** trunk.orig/gcc/gimple.c 2016-05-12 13:40:30.704262951 +0200
> > --- trunk/gcc/gimple.c 2016-05-12 14:49:37.066994969 +0200
> > *************** get_gimple_rhs_num_ops (enum tree_code c
> > *** 2044,2049 ****
> > --- 2044,2050 ----
> > || (SYM) == REALIGN_LOAD_EXPR \
> > || (SYM) == VEC_COND_EXPR \
> > || (SYM) == VEC_PERM_EXPR \
> > + || (SYM) == BIT_FIELD_INSERT \
> > || (SYM) == FMA_EXPR) ? GIMPLE_TERNARY_RHS \
> > : ((SYM) == CONSTRUCTOR \
> > || (SYM) == OBJ_TYPE_REF \
> > Index: trunk/gcc/tree-cfg.c
> > ===================================================================
> > *** trunk.orig/gcc/tree-cfg.c 2016-05-06 14:38:33.959495081 +0200
> > --- trunk/gcc/tree-cfg.c 2016-05-13 09:25:01.670630730 +0200
> > *************** verify_gimple_assign_ternary (gassign *s
> > *** 4155,4160 ****
> > --- 4155,4207 ----
> >
> > return false;
> >
> > + case BIT_FIELD_INSERT:
> > + if (! useless_type_conversion_p (lhs_type, rhs1_type))
> > + {
> > + error ("type mismatch in BIT_FIELD_INSERT");
> > + debug_generic_expr (lhs_type);
> > + debug_generic_expr (rhs1_type);
> > + return true;
> > + }
> > + if (! ((INTEGRAL_TYPE_P (rhs1_type)
> > + && INTEGRAL_TYPE_P (rhs2_type))
> > + || (VECTOR_TYPE_P (rhs1_type)
> > + && types_compatible_p (TREE_TYPE (rhs1_type), rhs2_type))))
> > + {
> > + error ("not allowed type combination in BIT_FIELD_INSERT");
> > + debug_generic_expr (rhs1_type);
> > + debug_generic_expr (rhs2_type);
> > + return true;
> > + }
> > + if (! tree_fits_uhwi_p (rhs3)
> > + || ! tree_fits_uhwi_p (TYPE_SIZE (rhs2_type)))
> > + {
> > + error ("invalid position or size in BIT_FIELD_INSERT");
> > + return true;
> > + }
> > + if (INTEGRAL_TYPE_P (rhs1_type))
> > + {
> > + unsigned HOST_WIDE_INT bitpos = tree_to_uhwi (rhs3);
> > + if (bitpos >= TYPE_PRECISION (rhs1_type)
> > + || (bitpos + TYPE_PRECISION (rhs2_type)
> > + > TYPE_PRECISION (rhs1_type)))
> > + {
> > + error ("insertion out of range in BIT_FIELD_INSERT");
> > + return true;
> > + }
> > + }
> > + else if (VECTOR_TYPE_P (rhs1_type))
> > + {
> > + unsigned HOST_WIDE_INT bitpos = tree_to_uhwi (rhs3);
> > + unsigned HOST_WIDE_INT bitsize = tree_to_uhwi (TYPE_SIZE (rhs2_type));
> > + if (bitpos % bitsize != 0)
> > + {
> > + error ("vector insertion not at element boundary");
> > + return true;
> > + }
> > + }
> > + return false;
> > +
> > case DOT_PROD_EXPR:
> > case REALIGN_LOAD_EXPR:
> > /* FIXME. */
> > Index: trunk/gcc/tree-ssa.c
> > ===================================================================
> > *** trunk.orig/gcc/tree-ssa.c 2016-05-13 09:38:02.263611726 +0200
> > --- trunk/gcc/tree-ssa.c 2016-05-13 09:50:31.020226585 +0200
> > *************** non_rewritable_lvalue_p (tree lhs)
> > *** 1318,1323 ****
> > --- 1318,1335 ----
> > return false;
> > }
> >
> > + /* A vector-insert using a BIT_FIELD_REF is rewritable using
> > + BIT_FIELD_INSERT. */
> > + if (TREE_CODE (lhs) == BIT_FIELD_REF
> > + && DECL_P (TREE_OPERAND (lhs, 0))
> > + && VECTOR_TYPE_P (TREE_TYPE (TREE_OPERAND (lhs, 0)))
> > + /* && bitsize % element-size == 0 */
> > + && types_compatible_p (TREE_TYPE (lhs),
> > + TREE_TYPE (TREE_TYPE (TREE_OPERAND (lhs, 0))))
> > + && (tree_to_uhwi (TREE_OPERAND (lhs, 2))
> > + % tree_to_uhwi (TYPE_SIZE (TREE_TYPE (lhs)))) == 0)
> > + return false;
> > +
> > return true;
> > }
> >
> > *************** execute_update_addresses_taken (void)
> > *** 1536,1541 ****
> > --- 1548,1576 ----
> > stmt = gsi_stmt (gsi);
> > unlink_stmt_vdef (stmt);
> > update_stmt (stmt);
> > + continue;
> > + }
> > +
> > + /* Rewrite a vector insert via a BIT_FIELD_REF on the LHS
> > + into a BIT_FIELD_INSERT. */
> > + if (TREE_CODE (lhs) == BIT_FIELD_REF
> > + && DECL_P (TREE_OPERAND (lhs, 0))
> > + && VECTOR_TYPE_P (TREE_TYPE (TREE_OPERAND (lhs, 0)))
> > + && types_compatible_p (TREE_TYPE (lhs),
> > + TREE_TYPE (TREE_TYPE
> > + (TREE_OPERAND (lhs, 0))))
> > + && (tree_to_uhwi (TREE_OPERAND (lhs, 2))
> > + % tree_to_uhwi (TYPE_SIZE (TREE_TYPE (lhs))) == 0))
> > + {
> > + tree var = TREE_OPERAND (lhs, 0);
> > + tree val = gimple_assign_rhs1 (stmt);
> > + tree bitpos = TREE_OPERAND (lhs, 2);
> > + gimple_assign_set_lhs (stmt, var);
> > + gimple_assign_set_rhs_with_ops
> > + (&gsi, BIT_FIELD_INSERT, var, val, bitpos);
> > + stmt = gsi_stmt (gsi);
> > + unlink_stmt_vdef (stmt);
> > + update_stmt (stmt);
> > continue;
> > }
> >
> > Index: trunk/gcc/testsuite/gcc.dg/tree-ssa/vector-6.c
> > ===================================================================
> > *** /dev/null 1970-01-01 00:00:00.000000000 +0000
> > --- trunk/gcc/testsuite/gcc.dg/tree-ssa/vector-6.c 2016-05-13 09:54:16.026814995 +0200
> > ***************
> > *** 0 ****
> > --- 1,34 ----
> > + /* { dg-do compile } */
> > + /* { dg-options "-O -fdump-tree-ccp1" } */
> > +
> > + typedef int v4si __attribute__((vector_size (4 * sizeof (int))));
> > +
> > + v4si test1 (v4si v, int i)
> > + {
> > + ((int *)&v)[0] = i;
> > + return v;
> > + }
> > +
> > + v4si test2 (v4si v, int i)
> > + {
> > + int *p = (int *)&v;
> > + *p = i;
> > + return v;
> > + }
> > +
> > + v4si test3 (v4si v, int i)
> > + {
> > + ((int *)&v)[3] = i;
> > + return v;
> > + }
> > +
> > + v4si test4 (v4si v, int i)
> > + {
> > + int *p = (int *)&v;
> > + p += 3;
> > + *p = i;
> > + return v;
> > + }
> > +
> > + /* { dg-final { scan-tree-dump-times "Now a gimple register: v" 2 "ccp1" } } */
> > + /* { dg-final { scan-tree-dump-times "Now a gimple register: v" 4 "ccp1" { xfail *-*-* } } } */
>
>
--
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)
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