On 6/29/18 8:19 PM, Cesar Philippidis wrote:
> The attached patch includes the nvptx and GCC ME reductions enhancements.
>
> Is this patch OK for trunk? It bootstrapped / regression tested cleanly
> for x86_64 with nvptx offloading.
>
These need fixing:
...
=== ERROR type #5: trailing whitespace (4 error(s)) ===
gcc/config/nvptx/nvptx.c:5139:0:██
gcc/config/nvptx/nvptx.c:5660:8: do█
gcc/config/nvptx/nvptx.c:5702:0:██
gcc/config/nvptx/nvptx.c:5726:0:██
...
> gcc/
> * config/nvptx/nvptx.c (nvptx_propagate_unified): New.
> (nvptx_split_blocks): Call it for cond_uni insn.
> (nvptx_expand_cond_uni): New.
> (enum nvptx_builtins): Add NVPTX_BUILTIN_COND_UNI.
> (nvptx_init_builtins): Initialize it.
> (nvptx_expand_builtin):
> (nvptx_generate_vector_shuffle): Change integral SHIFT operand to
> tree BITS operand.
> (nvptx_vector_reduction): New.
> (nvptx_adjust_reduction_type): New.
> (nvptx_goacc_reduction_setup): Use it to adjust the type of ref_to_res.
> (nvptx_goacc_reduction_init): Don't update LHS if it doesn't exist.
> (nvptx_goacc_reduction_fini): Call nvptx_vector_reduction for vector.
> Use it to adjust the type of ref_to_res.
> (nvptx_goacc_reduction_teardown):
> * config/nvptx/nvptx.md (cond_uni): New pattern.
> diff --git a/gcc/config/nvptx/nvptx.c b/gcc/config/nvptx/nvptx.c
> index 5608bee8a8d..33ec3db1153 100644
> --- a/gcc/config/nvptx/nvptx.c
> +++ b/gcc/config/nvptx/nvptx.c
> @@ -2863,6 +2863,52 @@ nvptx_reorg_uniform_simt ()
> }
> }
>
> +/* UNIFIED is a cond_uni insn. Find the branch insn it affects, and
> + mark that as unified. We expect to be in a single block. */
> +
> +static void
> +nvptx_propagate_unified (rtx_insn *unified)
> +{
> + rtx_insn *probe = unified;
> + rtx cond_reg = SET_DEST (PATTERN (unified));
> + rtx pat = NULL_RTX;
> +
> + /* Find the comparison. (We could skip this and simply scan to he
> + blocks' terminating branch, if we didn't care for self
> + checking.) */
> + for (;;)
> + {
> + probe = next_real_insn (probe);
> + if (!probe)
> + break;
> + pat = PATTERN (probe);
> +
> + if (GET_CODE (pat) == SET
> + && GET_RTX_CLASS (GET_CODE (SET_SRC (pat))) == RTX_COMPARE
> + && XEXP (SET_SRC (pat), 0) == cond_reg)
> + break;
> + gcc_assert (NONJUMP_INSN_P (probe));
> + }
> + gcc_assert (pat);
> + rtx pred_reg = SET_DEST (pat);
> +
> + /* Find the branch. */
> + do
> + probe = NEXT_INSN (probe);
> + while (!JUMP_P (probe));
> +
> + pat = PATTERN (probe);
> + rtx itec = XEXP (SET_SRC (pat), 0);
> + gcc_assert (XEXP (itec, 0) == pred_reg);
> +
> + /* Mark the branch's condition as unified. */
> + rtx unspec = gen_rtx_UNSPEC (BImode, gen_rtvec (1, pred_reg),
> + UNSPEC_BR_UNIFIED);
> + bool ok = validate_change (probe, &XEXP (itec, 0), unspec, false);
> +
> + gcc_assert (ok);
> +}
> +
> /* Loop structure of the function. The entire function is described as
> a NULL loop. */
>
> @@ -2964,6 +3010,9 @@ nvptx_split_blocks (bb_insn_map_t *map)
> continue;
> switch (recog_memoized (insn))
> {
> + case CODE_FOR_cond_uni:
> + nvptx_propagate_unified (insn);
> + /* FALLTHROUGH */
> default:
> seen_insn = true;
> continue;
> @@ -5080,6 +5129,21 @@ nvptx_expand_cmp_swap (tree exp, rtx target,
> return target;
> }
>
> +/* Expander for the compare unified builtin. */
> +
> +static rtx
> +nvptx_expand_cond_uni (tree exp, rtx target, machine_mode mode, int ignore)
> +{
> + if (ignore)
> + return target;
> +
> + rtx src = expand_expr (CALL_EXPR_ARG (exp, 0),
> + NULL_RTX, mode, EXPAND_NORMAL);
> +
> + emit_insn (gen_cond_uni (target, src));
> +
> + return target;
> +}
>
> /* Codes for all the NVPTX builtins. */
> enum nvptx_builtins
> @@ -5089,6 +5153,7 @@ enum nvptx_builtins
> NVPTX_BUILTIN_WORKER_ADDR,
> NVPTX_BUILTIN_CMP_SWAP,
> NVPTX_BUILTIN_CMP_SWAPLL,
> + NVPTX_BUILTIN_COND_UNI,
> NVPTX_BUILTIN_MAX
> };
>
> @@ -5126,6 +5191,7 @@ nvptx_init_builtins (void)
> (PTRVOID, ST, UINT, UINT, NULL_TREE));
> DEF (CMP_SWAP, "cmp_swap", (UINT, PTRVOID, UINT, UINT, NULL_TREE));
> DEF (CMP_SWAPLL, "cmp_swapll", (LLUINT, PTRVOID, LLUINT, LLUINT,
> NULL_TREE));
> + DEF (COND_UNI, "cond_uni", (integer_type_node, integer_type_node,
> NULL_TREE));
>
> #undef DEF
> #undef ST
> @@ -5158,6 +5224,9 @@ nvptx_expand_builtin (tree exp, rtx target, rtx
> ARG_UNUSED (subtarget),
> case NVPTX_BUILTIN_CMP_SWAPLL:
> return nvptx_expand_cmp_swap (exp, target, mode, ignore);
>
> + case NVPTX_BUILTIN_COND_UNI:
> + return nvptx_expand_cond_uni (exp, target, mode, ignore);
> +
> default: gcc_unreachable ();
> }
> }
> @@ -5284,7 +5353,7 @@ nvptx_get_worker_red_addr (tree type, tree offset)
>
> static void
> nvptx_generate_vector_shuffle (location_t loc,
> - tree dest_var, tree var, unsigned shift,
> + tree dest_var, tree var, tree bits,
> gimple_seq *seq)
> {
> unsigned fn = NVPTX_BUILTIN_SHUFFLE;
> @@ -5307,7 +5376,6 @@ nvptx_generate_vector_shuffle (location_t loc,
> }
>
> tree call = nvptx_builtin_decl (fn, true);
> - tree bits = build_int_cst (unsigned_type_node, shift);
> tree kind = build_int_cst (unsigned_type_node, SHUFFLE_DOWN);
> tree expr;
>
> @@ -5583,6 +5651,126 @@ nvptx_reduction_update (location_t loc,
> gimple_stmt_iterator *gsi,
> return nvptx_lockfull_update (loc, gsi, ptr, var, op);
> }
>
> +/* Emit a vector-level reduction loop. OLD_VAR is the incoming
> + variable to reduce (valid in each vector), OP is the reduction
> + operator. Return the reduced value (an SSA var).
> +
> + The code we generate looks like:
> + unsigned old_shift = DIM_SIZE(VECTOR);
> + do
> + {
> + shift = PHI (old_shift, new_shift);
> + var = PHI (old_var, new_var);
> + new_shift = shift >> 1;
> + other_var = VSHUFFLE (var, new_shift);
> + new_var = var OP other_var;
> + cond_var = builtin_cond_uni (new_shift);
> + }
> + while (cond_var > 1);
> +
> + The builtin_cond_ini expands to a cond_uni instruction, which is
> + processed in nvpts_split_blocks to mark the loop's terminating
> + branch instruction. */
> +
> +static tree
> +nvptx_vector_reduction (location_t loc, gimple_stmt_iterator *gsi,
> + tree old_var, tree_code op)
> +{
> + tree var_type = TREE_TYPE (old_var);
> +
> + /* Emit old_shift = DIM_SIZE(VECTOR) */
> + tree old_shift = make_ssa_name (integer_type_node);
> + tree dim = build_int_cst (integer_type_node, GOMP_DIM_VECTOR);
> + gcall *call = gimple_build_call_internal (IFN_GOACC_DIM_SIZE, 1, dim);
> + gimple_set_lhs (call, old_shift);
> + gimple_set_location (call, loc);
> + gsi_insert_before (gsi, call, GSI_SAME_STMT);
> +
> + /* Split the block just after the init stmts. */
> + basic_block pre_bb = gsi_bb (*gsi);
> + edge pre_edge = split_block (pre_bb, call);
> + basic_block loop_bb = pre_edge->dest;
> + pre_bb = pre_edge->src;
> + /* Reset the iterator. */
> + *gsi = gsi_for_stmt (gsi_stmt (*gsi));
> +
> + tree shift = make_ssa_name (integer_type_node);
> + tree new_shift = make_ssa_name (integer_type_node);
> + tree var = make_ssa_name (var_type);
> + tree other_var = make_ssa_name (var_type);
> + tree new_var = make_ssa_name (var_type);
> +
> + /* Build and insert the loop body. */
> + gimple_seq loop_seq = NULL;
> +
> + /* new_shift = shift >> 1 */
> + tree shift_expr = fold_build2 (RSHIFT_EXPR, integer_type_node,
> + shift, integer_one_node);
> + gimplify_assign (new_shift, shift_expr, &loop_seq);
> +
> + /* other_var = shuffle (var, shift) */
> + nvptx_generate_vector_shuffle (loc, other_var, var, new_shift, &loop_seq);
> + /* new_var = var OP other_var */
> + tree red_expr = fold_build2 (op, var_type, var, other_var);
> + gimplify_assign (new_var, red_expr, &loop_seq);
> +
> + /* Mark the iterator variable as unified. */
> + tree cond_var = make_ssa_name (integer_type_node);
> + tree uni_fn = nvptx_builtin_decl (NVPTX_BUILTIN_COND_UNI, true);
> + tree uni_expr = build_call_expr_loc (loc, uni_fn, 1, new_shift);
> + gimplify_assign (cond_var, uni_expr, &loop_seq);
> +
> + gcond *cond = gimple_build_cond (LE_EXPR, cond_var, integer_one_node,
> + NULL_TREE, NULL_TREE);
> + gimple_seq_add_stmt (&loop_seq, cond);
> +
> + gsi_insert_seq_before (gsi, loop_seq, GSI_SAME_STMT);
> +
> + /* Split the block just after the loop stmts. */
> + edge post_edge = split_block (loop_bb, cond);
> + basic_block post_bb = post_edge->dest;
> + loop_bb = post_edge->src;
> + *gsi = gsi_for_stmt (gsi_stmt (*gsi));
> +
> + /* Create the loop. */
> + post_edge->flags ^= EDGE_TRUE_VALUE | EDGE_FALLTHRU;
Edges need probabilities, as in nvptx_lockless_update,
nvptx_lockfull_update and nvptx_goacc_reduction_init.
> + edge loop_edge = make_edge (loop_bb, loop_bb, EDGE_FALSE_VALUE);
> + set_immediate_dominator (CDI_DOMINATORS, loop_bb, pre_bb);
> + set_immediate_dominator (CDI_DOMINATORS, post_bb, loop_bb);
> +
> + gphi *shift_phi = create_phi_node (shift, loop_bb);
> + add_phi_arg (shift_phi, old_shift, pre_edge, loc);
> + add_phi_arg (shift_phi, new_shift, loop_edge, loc);
> +
> + gphi *var_phi = create_phi_node (var, loop_bb);
> + add_phi_arg (var_phi, old_var, pre_edge, loc);
> + add_phi_arg (var_phi, new_var, loop_edge, loc);
> +
> + loop *loop = alloc_loop ();
> + loop->header = loop_bb;
> + loop->latch = loop_bb;
> + add_loop (loop, loop_bb->loop_father);
> +
> + return new_var;
> +}
> +
> +/* Dummy reduction vars that have GOMP_MAP_FIRSTPRIVATE_POINTER data
> + mappings gets retyped to (void *). Adjust the type of VAR to TYPE
> + as appropriate. */
> +
> +static tree
> +nvptx_adjust_reduction_type (tree var, tree type, gimple_seq *seq)
> +{
> + if (TREE_TYPE (TREE_TYPE (var)) == type)
> + return var;
> +
> + tree ptype = build_pointer_type (type);
> + tree t = make_ssa_name (ptype);
> + tree expr = fold_build1 (NOP_EXPR, ptype, var);
> + gimple_seq_add_stmt (seq, gimple_build_assign (t, expr));
> + return t;
> +}
> +
> /* NVPTX implementation of GOACC_REDUCTION_SETUP. */
>
> static void
> @@ -5602,7 +5790,11 @@ nvptx_goacc_reduction_setup (gcall *call)
> tree ref_to_res = gimple_call_arg (call, 1);
>
> if (!integer_zerop (ref_to_res))
> - var = build_simple_mem_ref (ref_to_res);
> + {
> + ref_to_res = nvptx_adjust_reduction_type (ref_to_res, TREE_TYPE (var),
> + &seq);
> + var = build_simple_mem_ref (ref_to_res);
> + }
> }
>
> if (level == GOMP_DIM_WORKER)
> @@ -5702,7 +5894,11 @@ nvptx_goacc_reduction_init (gcall *call)
> init = var;
> }
>
> - gimplify_assign (lhs, init, &seq);
> + /* The LHS may be NULL if a reduction variable on a parallel
> + construct is initialized to some constant inside the parallel
> + region. */
> + if (lhs)
> + gimplify_assign (lhs, init, &seq);
> }
>
> pop_gimplify_context (NULL);
> @@ -5727,22 +5923,7 @@ nvptx_goacc_reduction_fini (gcall *call)
> push_gimplify_context (true);
>
> if (level == GOMP_DIM_VECTOR)
> - {
> - /* Emit binary shuffle tree. TODO. Emit this as an actual loop,
> - but that requires a method of emitting a unified jump at the
> - gimple level. */
> - for (int shfl = PTX_VECTOR_LENGTH / 2; shfl > 0; shfl = shfl >> 1)
> - {
> - tree other_var = make_ssa_name (TREE_TYPE (var));
> - nvptx_generate_vector_shuffle (gimple_location (call),
> - other_var, var, shfl, &seq);
> -
> - r = make_ssa_name (TREE_TYPE (var));
> - gimplify_assign (r, fold_build2 (op, TREE_TYPE (var),
> - var, other_var), &seq);
> - var = r;
> - }
> - }
> + r = nvptx_vector_reduction (gimple_location (call), &gsi, var, op);
> else
> {
> tree accum = NULL_TREE;
> @@ -5760,7 +5941,11 @@ nvptx_goacc_reduction_fini (gcall *call)
> else if (integer_zerop (ref_to_res))
> r = var;
> else
> - accum = ref_to_res;
> + {
> + ref_to_res = nvptx_adjust_reduction_type (ref_to_res, TREE_TYPE (var),
> + &seq);
> + accum = ref_to_res;
> + }
>
> if (accum)
> {
> @@ -5809,7 +5994,11 @@ nvptx_goacc_reduction_teardown (gcall *call)
> tree ref_to_res = gimple_call_arg (call, 1);
>
> if (!integer_zerop (ref_to_res))
> - gimplify_assign (build_simple_mem_ref (ref_to_res), var, &seq);
> + {
> + ref_to_res = nvptx_adjust_reduction_type (ref_to_res, TREE_TYPE (var),
> + &seq);
> + gimplify_assign (build_simple_mem_ref (ref_to_res), var, &seq);
> + }
> }
>
> if (lhs)
> diff --git a/gcc/config/nvptx/nvptx.md b/gcc/config/nvptx/nvptx.md
> index 2988f5dfa91..79c4c061841 100644
> --- a/gcc/config/nvptx/nvptx.md
> +++ b/gcc/config/nvptx/nvptx.md
> @@ -600,6 +600,13 @@
> "%J0\\tbra.uni\\t%l1;"
> [(set_attr "predicable" "false")])
>
> +(define_insn "cond_uni"
> + [(set (match_operand:SI 0 "nvptx_register_operand" "=R")
> + (unspec:SI [(match_operand:SI 1 "nvptx_nonmemory_operand" "R")]
> + UNSPEC_BR_UNIFIED))]
> + ""
> + "%.\\tmov%t0\\t%0, %1; // unified")
> +
> (define_expand "cbranch<mode>4"
> [(set (pc)
> (if_then_else (match_operator 0 "nvptx_comparison_operator"
Otherwise, nvptx part LGTM.
Thanks,
- Tom
