On Thu, Jun 16, 2022 at 4:11 AM Tamar Christina via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Hi All,
>
> This patch adds support for three-way min/max recognition in phi-opts.
>
> Concretely for e.g.
>
> #include <stdint.h>
>
> uint8_t three_min (uint8_t xc, uint8_t xm, uint8_t xy) {
> uint8_t xk;
> if (xc < xm) {
> xk = (uint8_t) (xc < xy ? xc : xy);
> } else {
> xk = (uint8_t) (xm < xy ? xm : xy);
> }
> return xk;
> }
>
> we generate:
>
> <bb 2> [local count: 1073741824]:
> _5 = MIN_EXPR <xc_1(D), xy_3(D)>;
> _7 = MIN_EXPR <xm_2(D), _5>;
> return _7;
>
> instead of
>
> <bb 2>:
> if (xc_2(D) < xm_3(D))
> goto <bb 3>;
> else
> goto <bb 4>;
>
> <bb 3>:
> xk_5 = MIN_EXPR <xc_2(D), xy_4(D)>;
> goto <bb 5>;
>
> <bb 4>:
> xk_6 = MIN_EXPR <xm_3(D), xy_4(D)>;
>
> <bb 5>:
> # xk_1 = PHI <xk_5(3), xk_6(4)>
> return xk_1;
>
> The same function also immediately deals with turning a minimization problem
> into a maximization one if the results are inverted. We do this here since
> doing it in match.pd would end up changing the shape of the BBs and adding
> additional instructions which would prevent various optimizations from
> working.
>
> Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
>
> Ok for master?
>
> Thanks,
> Tamar
>
> gcc/ChangeLog:
>
> * tree-ssa-phiopt.cc (minmax_replacement): Optionally search for the
> phi
> sequence of a three-way conditional.
> (replace_phi_edge_with_variable): Support deferring of BB removal.
> (tree_ssa_phiopt_worker): Detect diamond phi structure for three-way
> min/max.
> (strip_bit_not, invert_minmax_code): New.
I have been working on getting rid of minmax_replacement and a few
others and only having match_simplify_replacement and having the
simplification logic all in match.pd instead.
Is there a reason why you can't expand match_simplify_replacement and match.pd?
>The reason was that a lot of the foldings checked that the BB contains only
> a single SSA and that that SSA is a phi node.
Could you expand on that?
Thanks,
Andrew
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/tree-ssa/split-path-1.c: Disable phi-opts so we don't
> optimize
> code away.
> * gcc.dg/tree-ssa/minmax-3.c: New test.
> * gcc.dg/tree-ssa/minmax-4.c: New test.
> * gcc.dg/tree-ssa/minmax-5.c: New test.
> * gcc.dg/tree-ssa/minmax-6.c: New test.
> * gcc.dg/tree-ssa/minmax-7.c: New test.
> * gcc.dg/tree-ssa/minmax-8.c: New test.
>
> --- inline copy of patch --
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-3.c
> b/gcc/testsuite/gcc.dg/tree-ssa/minmax-3.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..de3b2e946e81701e3b75f580e6a843695a05786e
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-3.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O -fdump-tree-phiopt" } */
> +
> +#include <stdint.h>
> +
> +uint8_t three_min (uint8_t xc, uint8_t xm, uint8_t xy) {
> + uint8_t xk;
> + if (xc < xm) {
> + xk = (uint8_t) (xc < xy ? xc : xy);
> + } else {
> + xk = (uint8_t) (xm < xy ? xm : xy);
> + }
> + return xk;
> +}
> +
> +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 3 "phiopt1" } } */
> +/* { dg-final { scan-tree-dump-times "MAX_EXPR" 0 "phiopt1" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-4.c
> b/gcc/testsuite/gcc.dg/tree-ssa/minmax-4.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..0b6d667be868c2405eaefd17cb522da44bafa0e2
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-4.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O -fdump-tree-phiopt" } */
> +
> +#include <stdint.h>
> +
> +uint8_t three_max (uint8_t xc, uint8_t xm, uint8_t xy) {
> + uint8_t xk;
> + if (xc > xm) {
> + xk = (uint8_t) (xc > xy ? xc : xy);
> + } else {
> + xk = (uint8_t) (xm > xy ? xm : xy);
> + }
> + return xk;
> +}
> +
> +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 0 "phiopt1" } } */
> +/* { dg-final { scan-tree-dump-times "MAX_EXPR" 3 "phiopt1" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-5.c
> b/gcc/testsuite/gcc.dg/tree-ssa/minmax-5.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..650601a3cc75d09a9e6e54a35f5b9993074f8510
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-5.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O -fdump-tree-phiopt" } */
> +
> +#include <stdint.h>
> +
> +uint8_t three_minmax1 (uint8_t xc, uint8_t xm, uint8_t xy) {
> + uint8_t xk;
> + if (xc > xm) {
> + xk = (uint8_t) (xc < xy ? xc : xy);
> + } else {
> + xk = (uint8_t) (xm < xy ? xm : xy);
> + }
> + return xk;
> +}
> +
> +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 2 "phiopt1" } } */
> +/* { dg-final { scan-tree-dump-times "MAX_EXPR" 1 "phiopt1" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-6.c
> b/gcc/testsuite/gcc.dg/tree-ssa/minmax-6.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..a628f6d99222958cfd8c410f0e85639e3a49dd4b
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-6.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O -fdump-tree-phiopt" } */
> +
> +#include <stdint.h>
> +
> +uint8_t three_minmax3 (uint8_t xc, uint8_t xm, uint8_t xy) {
> + uint8_t xk;
> + if (xc > xm) {
> + xk = (uint8_t) (xy < xc ? xc : xy);
> + } else {
> + xk = (uint8_t) (xm < xy ? xm : xy);
> + }
> + return xk;
> +}
> +
> +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "phiopt1" } } */
> +/* { dg-final { scan-tree-dump-times "MAX_EXPR" 1 "phiopt1" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-7.c
> b/gcc/testsuite/gcc.dg/tree-ssa/minmax-7.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..cb42412c4ada433b2f59df0a8bef9fa7b1c5e104
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-7.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O -fdump-tree-phiopt" } */
> +
> +#include <stdint.h>
> +
> +uint8_t three_minmax2 (uint8_t xc, uint8_t xm, uint8_t xy) {
> + uint8_t xk;
> + if (xc > xm) {
> + xk = (uint8_t) (xc > xy ? xc : xy);
> + } else {
> + xk = (uint8_t) (xm < xy ? xm : xy);
> + }
> + return xk;
> +}
> +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "phiopt1" } } */
> +/* { dg-final { scan-tree-dump-times "MAX_EXPR" 1 "phiopt1" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-8.c
> b/gcc/testsuite/gcc.dg/tree-ssa/minmax-8.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..9cd050e932376bc50bd6ae60cb654fcab0bfdd1c
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-8.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O -fdump-tree-phiopt" } */
> +
> +#include <stdint.h>
> +
> +uint8_t three_minmax11 (uint8_t xc, uint8_t xm, uint8_t xy) {
> + uint8_t xk;
> + if (xc < xm) {
> + xk = (uint8_t) (xc > xy ? xc : xy);
> + } else {
> + xk = (uint8_t) (xm > xy ? xm : xy);
> + }
> + return xk;
> +}
> +
> +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "phiopt1" } } */
> +/* { dg-final { scan-tree-dump-times "MAX_EXPR" 2 "phiopt1" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/split-path-1.c
> b/gcc/testsuite/gcc.dg/tree-ssa/split-path-1.c
> index
> 8b23ef4c7a3484cdc1647ee6d1b150f15685beff..902dde44a50e171b4f34ba7247d75a32d2c860ed
> 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/split-path-1.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/split-path-1.c
> @@ -1,5 +1,5 @@
> /* { dg-do run } */
> -/* { dg-options "-O2 -fsplit-paths -fdump-tree-split-paths-details --param
> max-jump-thread-duplication-stmts=20" } */
> +/* { dg-options "-O2 -fsplit-paths -fdump-tree-split-paths-details --param
> max-jump-thread-duplication-stmts=20 -fno-ssa-phiopt" } */
>
> #include <stdio.h>
> #include <stdlib.h>
> diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
> index
> 562468b7f02a9ffe2713318add551902c14f89c3..6246f054006ff16e73602e7ce2e367d2d21421b1
> 100644
> --- a/gcc/tree-ssa-phiopt.cc
> +++ b/gcc/tree-ssa-phiopt.cc
> @@ -62,8 +62,8 @@ static gphi *factor_out_conditional_conversion (edge, edge,
> gphi *, tree, tree,
> gimple *);
> static int value_replacement (basic_block, basic_block,
> edge, edge, gphi *, tree, tree);
> -static bool minmax_replacement (basic_block, basic_block,
> - edge, edge, gphi *, tree, tree);
> +static bool minmax_replacement (basic_block, basic_block, basic_block,
> + edge, edge, gphi *, tree, tree, bool);
> static bool spaceship_replacement (basic_block, basic_block,
> edge, edge, gphi *, tree, tree);
> static bool cond_removal_in_builtin_zero_pattern (basic_block, basic_block,
> @@ -73,7 +73,7 @@ static bool cond_store_replacement (basic_block,
> basic_block, edge, edge,
> hash_set<tree> *);
> static bool cond_if_else_store_replacement (basic_block, basic_block,
> basic_block);
> static hash_set<tree> * get_non_trapping ();
> -static void replace_phi_edge_with_variable (basic_block, edge, gphi *, tree);
> +static void replace_phi_edge_with_variable (basic_block, edge, gphi *, tree,
> bool);
> static void hoist_adjacent_loads (basic_block, basic_block,
> basic_block, basic_block);
> static bool gate_hoist_loads (void);
> @@ -199,6 +199,7 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool
> do_hoist_loads, bool early_p)
> basic_block bb1, bb2;
> edge e1, e2;
> tree arg0, arg1;
> + bool diamond_minmax_p = false;
>
> bb = bb_order[i];
>
> @@ -265,6 +266,29 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool
> do_hoist_loads, bool early_p)
> hoist_adjacent_loads (bb, bb1, bb2, bb3);
> continue;
> }
> + else if (EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest
> + && single_succ_p (bb1)
> + && single_succ_p (bb2)
> + && single_pred_p (bb1)
> + && single_pred_p (bb2)
> + && single_succ_p (EDGE_SUCC (bb1, 0)->dest))
> + {
> + gimple_stmt_iterator it1 = gsi_start_nondebug_after_labels_bb (bb1);
> + gimple_stmt_iterator it2 = gsi_start_nondebug_after_labels_bb (bb2);
> + if (gsi_one_before_end_p (it1) && gsi_one_before_end_p (it2))
> + {
> + gimple *stmt1 = gsi_stmt (it1);
> + gimple *stmt2 = gsi_stmt (it2);
> + if (is_gimple_assign (stmt1) && is_gimple_assign (stmt2))
> + {
> + enum tree_code code1 = gimple_assign_rhs_code (stmt1);
> + enum tree_code code2 = gimple_assign_rhs_code (stmt2);
> + diamond_minmax_p
> + = (code1 == MIN_EXPR || code1 == MAX_EXPR)
> + && (code2 == MIN_EXPR || code2 == MAX_EXPR);
> + }
> + }
> + }
> else
> continue;
>
> @@ -316,6 +340,13 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool
> do_hoist_loads, bool early_p)
> if (!candorest)
> continue;
>
> + /* Check that we're looking for nested phis. */
> + if (phis == NULL && diamond_minmax_p)
> + {
> + phis = phi_nodes (EDGE_SUCC (bb2, 0)->dest);
> + e2 = EDGE_SUCC (bb2, 0);
> + }
> +
> phi = single_non_singleton_phi_for_edges (phis, e1, e2);
> if (!phi)
> continue;
> @@ -329,6 +360,7 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool
> do_hoist_loads, bool early_p)
>
> gphi *newphi;
> if (single_pred_p (bb1)
> + && !diamond_minmax_p
> && (newphi = factor_out_conditional_conversion (e1, e2, phi,
> arg0, arg1,
> cond_stmt)))
> @@ -343,20 +375,25 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool
> do_hoist_loads, bool early_p)
> }
>
> /* Do the replacement of conditional if it can be done. */
> - if (!early_p && two_value_replacement (bb, bb1, e2, phi, arg0,
> arg1))
> + if (!early_p
> + && !diamond_minmax_p
> + && two_value_replacement (bb, bb1, e2, phi, arg0, arg1))
> cfgchanged = true;
> - else if (match_simplify_replacement (bb, bb1, e1, e2, phi,
> - arg0, arg1,
> - early_p))
> + else if (!diamond_minmax_p
> + && match_simplify_replacement (bb, bb1, e1, e2, phi,
> + arg0, arg1, early_p))
> cfgchanged = true;
> else if (!early_p
> + && !diamond_minmax_p
> && single_pred_p (bb1)
> && cond_removal_in_builtin_zero_pattern (bb, bb1, e1, e2,
> phi, arg0, arg1))
> cfgchanged = true;
> - else if (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
> + else if (minmax_replacement (bb, bb1, bb2, e1, e2, phi, arg0, arg1,
> + diamond_minmax_p))
> cfgchanged = true;
> else if (single_pred_p (bb1)
> + && !diamond_minmax_p
> && spaceship_replacement (bb, bb1, e1, e2, phi, arg0,
> arg1))
> cfgchanged = true;
> }
> @@ -385,7 +422,7 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool
> do_hoist_loads, bool early_p)
>
> static void
> replace_phi_edge_with_variable (basic_block cond_block,
> - edge e, gphi *phi, tree new_tree)
> + edge e, gphi *phi, tree new_tree, bool
> delete_bb = true)
> {
> basic_block bb = gimple_bb (phi);
> gimple_stmt_iterator gsi;
> @@ -428,7 +465,7 @@ replace_phi_edge_with_variable (basic_block cond_block,
> edge_to_remove = EDGE_SUCC (cond_block, 1);
> else
> edge_to_remove = EDGE_SUCC (cond_block, 0);
> - if (EDGE_COUNT (edge_to_remove->dest->preds) == 1)
> + if (EDGE_COUNT (edge_to_remove->dest->preds) == 1 && delete_bb)
> {
> e->flags |= EDGE_FALLTHRU;
> e->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
> @@ -1564,15 +1601,52 @@ value_replacement (basic_block cond_bb, basic_block
> middle_bb,
> return 0;
> }
>
> +/* If VAR is an SSA_NAME that points to a BIT_NOT_EXPR then return the TREE
> for
> + the value being inverted. */
> +
> +static tree
> +strip_bit_not (tree var)
> +{
> + if (TREE_CODE (var) != SSA_NAME)
> + return NULL_TREE;
> +
> + gimple *assign = SSA_NAME_DEF_STMT (var);
> + if (gimple_code (assign) != GIMPLE_ASSIGN)
> + return NULL_TREE;
> +
> + if (gimple_assign_rhs_code (assign) != BIT_NOT_EXPR)
> + return NULL_TREE;
> +
> + return gimple_assign_rhs1 (assign);
> +}
> +
> +/* Invert a MIN to a MAX or a MAX to a MIN expression CODE. */
> +
> +enum tree_code
> +invert_minmax_code (enum tree_code code)
> +{
> + switch (code) {
> + case MIN_EXPR:
> + return MAX_EXPR;
> + case MAX_EXPR:
> + return MIN_EXPR;
> + default:
> + gcc_unreachable ();
> + }
> +}
> +
> /* The function minmax_replacement does the main work of doing the minmax
> replacement. Return true if the replacement is done. Otherwise return
> false.
> BB is the basic block where the replacement is going to be done on. ARG0
> - is argument 0 from the PHI. Likewise for ARG1. */
> + is argument 0 from the PHI. Likewise for ARG1.
> +
> + If THREEWAY_P then expect the BB to be laid out in diamond shape with
> each
> + BB containing only a MIN or MAX expression. */
>
> static bool
> -minmax_replacement (basic_block cond_bb, basic_block middle_bb,
> - edge e0, edge e1, gphi *phi, tree arg0, tree arg1)
> +minmax_replacement (basic_block cond_bb, basic_block middle_bb, basic_block
> alt_middle_bb,
> + edge e0, edge e1, gphi *phi, tree arg0, tree arg1, bool
> threeway_p)
> {
> tree result;
> edge true_edge, false_edge;
> @@ -1727,9 +1801,14 @@ minmax_replacement (basic_block cond_bb, basic_block
> middle_bb,
> if (false_edge->dest == middle_bb)
> false_edge = EDGE_SUCC (false_edge->dest, 0);
>
> + /* When THREEWAY_P then e1 will point to the edge of the final transition
> + from middle-bb to end. */
> if (true_edge == e0)
> {
> - gcc_assert (false_edge == e1);
> + if (threeway_p)
> + gcc_assert (false_edge == EDGE_PRED (e1->src, 0));
> + else
> + gcc_assert (false_edge == e1);
> arg_true = arg0;
> arg_false = arg1;
> }
> @@ -1768,6 +1847,133 @@ minmax_replacement (basic_block cond_bb, basic_block
> middle_bb,
> else
> return false;
> }
> + else if (middle_bb != alt_middle_bb && threeway_p)
> + {
> + /* Recognize the following case:
> +
> + if (smaller < larger)
> + a = MIN (smaller, c);
> + else
> + b = MIN (larger, c);
> + x = PHI <a, b>
> +
> + This is equivalent to
> +
> + a = MIN (smaller, c);
> + x = MIN (larger, a); */
> +
> + gimple *assign = last_and_only_stmt (middle_bb);
> + tree lhs, op0, op1, bound;
> + tree alt_lhs, alt_op0, alt_op1;
> + bool invert = false;
> +
> + if (!single_pred_p (middle_bb)
> + || !single_pred_p (alt_middle_bb))
> + return false;
> +
> + if (!assign
> + || gimple_code (assign) != GIMPLE_ASSIGN)
> + return false;
> +
> + lhs = gimple_assign_lhs (assign);
> + ass_code = gimple_assign_rhs_code (assign);
> + if (ass_code != MAX_EXPR && ass_code != MIN_EXPR)
> + return false;
> +
> + op0 = gimple_assign_rhs1 (assign);
> + op1 = gimple_assign_rhs2 (assign);
> +
> + assign = last_and_only_stmt (alt_middle_bb);
> + if (!assign
> + || gimple_code (assign) != GIMPLE_ASSIGN)
> + return false;
> +
> + alt_lhs = gimple_assign_lhs (assign);
> + if (ass_code != gimple_assign_rhs_code (assign))
> + return false;
> +
> + alt_op0 = gimple_assign_rhs1 (assign);
> + alt_op1 = gimple_assign_rhs2 (assign);
> +
> + if (!operand_equal_for_phi_arg_p (lhs, arg_true)
> + || !operand_equal_for_phi_arg_p (alt_lhs, arg_false))
> + return false;
> +
> + if ((operand_equal_for_phi_arg_p (op0, smaller)
> + || (alt_smaller
> + && operand_equal_for_phi_arg_p (op0, alt_smaller)))
> + && (operand_equal_for_phi_arg_p (alt_op0, larger)
> + || (alt_larger
> + && operand_equal_for_phi_arg_p (alt_op0, alt_larger))))
> + {
> + /* We got here if the condition is true, i.e., SMALLER < LARGER. */
> + if (!operand_equal_for_phi_arg_p (op1, alt_op1))
> + return false;
> +
> + if ((arg0 = strip_bit_not (op0)) != NULL
> + && (arg1 = strip_bit_not (alt_op0)) != NULL
> + && (bound = strip_bit_not (op1)) != NULL)
> + {
> + minmax = MAX_EXPR;
> + ass_code = invert_minmax_code (ass_code);
> + invert = true;
> + }
> + else
> + {
> + bound = op1;
> + minmax = MIN_EXPR;
> + arg0 = op0;
> + arg1 = alt_op0;
> + }
> + }
> + else if ((operand_equal_for_phi_arg_p (op0, larger)
> + || (alt_larger
> + && operand_equal_for_phi_arg_p (op0, alt_larger)))
> + && (operand_equal_for_phi_arg_p (alt_op0, smaller)
> + || (alt_smaller
> + && operand_equal_for_phi_arg_p (alt_op0,
> alt_smaller))))
> + {
> + /* We got here if the condition is true, i.e., SMALLER > LARGER. */
> + if (!operand_equal_for_phi_arg_p (op1, alt_op1))
> + return false;
> +
> + if ((arg0 = strip_bit_not (op0)) != NULL
> + && (arg1 = strip_bit_not (alt_op0)) != NULL
> + && (bound = strip_bit_not (op1)) != NULL)
> + {
> + minmax = MIN_EXPR;
> + ass_code = invert_minmax_code (ass_code);
> + invert = true;
> + }
> + else
> + {
> + bound = op1;
> + minmax = MAX_EXPR;
> + arg0 = op0;
> + arg1 = alt_op0;
> + }
> + }
> + else
> + return false;
> +
> + /* Reset any range information from the basic block. */
> + reset_flow_sensitive_info_in_bb (cond_bb);
> +
> + /* Emit the statement to compute min/max. */
> + gimple_seq stmts = NULL;
> + tree phi_result = PHI_RESULT (phi);
> + result = gimple_build (&stmts, minmax, TREE_TYPE (phi_result), arg0,
> bound);
> + result = gimple_build (&stmts, ass_code, TREE_TYPE (phi_result),
> result, arg1);
> + if (invert)
> + result = gimple_build (&stmts, BIT_NOT_EXPR, TREE_TYPE (phi_result),
> result);
> +
> + gsi = gsi_last_bb (cond_bb);
> + gsi_insert_seq_before (&gsi, stmts, GSI_NEW_STMT);
> +
> + replace_phi_edge_with_variable (cond_bb, e1, phi, result, false);
> +
> + return true;
> + }
> else
> {
> /* Recognize the following case, assuming d <= u:
>
>
>
>
> --
