===================================================================
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-phiopt1" } */
+
+int f(int a, int b, int c) {
+ if (c > 5) return c;
+ if (a == 0) return b;
+ return a + b;
+}
+
+unsigned rot(unsigned x, int n) {
+ const int bits = __CHAR_BIT__ * __SIZEOF_INT__;
+ return (n == 0) ? x : ((x << n) | (x >> (bits - n)));
+}
+
+unsigned m(unsigned a, unsigned b) {
+ if (a == 0)
+ return 0;
+ else
+ return a & b;
+}
+
+/* { dg-final { scan-tree-dump-times "goto" 2 "phiopt1" } } */
+/* { dg-final { cleanup-tree-dump "phiopt1" } } */
===================================================================
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+// Division is expensive
+long f(long a, long b) {
+ if (__builtin_expect(b == 1, 1)) return a;
+ return a / b;
+}
+
+/* { dg-final { scan-tree-dump-times "goto " 2 "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
===================================================================
@@ -47,20 +47,21 @@ along with GCC; see the file COPYING3.
#include "tree-pass.h"
#include "langhooks.h"
#include "domwalk.h"
#include "cfgloop.h"
#include "tree-data-ref.h"
#include "gimple-pretty-print.h"
#include "insn-config.h"
#include "expr.h"
#include "optabs.h"
#include "tree-scalar-evolution.h"
+#include "tree-inline.h"
#ifndef HAVE_conditional_move
#define HAVE_conditional_move (0)
#endif
static unsigned int tree_ssa_phiopt_worker (bool, bool);
static bool conditional_replacement (basic_block, basic_block,
edge, edge, gimple, tree, tree);
static int value_replacement (basic_block, basic_block,
edge, edge, gimple, tree, tree);
@@ -652,20 +653,78 @@ operand_equal_for_value_replacement (con
if (rhs_is_fed_for_value_replacement (arg0, arg1, code, tmp))
return true;
tmp = gimple_assign_rhs2 (def);
if (rhs_is_fed_for_value_replacement (arg0, arg1, code, tmp))
return true;
return false;
}
+/* Returns true if ARG is a neutral element for operation CODE
+ on the RIGHT side. */
+
+static bool
+neutral_element_p (tree_code code, tree arg, bool right)
+{
+ switch (code)
+ {
+ case PLUS_EXPR:
+ case BIT_IOR_EXPR:
+ case BIT_XOR_EXPR:
+ return integer_zerop (arg);
+
+ case LROTATE_EXPR:
+ case RROTATE_EXPR:
+ case LSHIFT_EXPR:
+ case RSHIFT_EXPR:
+ case MINUS_EXPR:
+ case POINTER_PLUS_EXPR:
+ return right && integer_zerop (arg);
+
+ case MULT_EXPR:
+ return integer_onep (arg);
+
+ case TRUNC_DIV_EXPR:
+ case CEIL_DIV_EXPR:
+ case FLOOR_DIV_EXPR:
+ case ROUND_DIV_EXPR:
+ case EXACT_DIV_EXPR:
+ return right && integer_onep (arg);
+
+ case BIT_AND_EXPR:
+ return integer_all_onesp (arg);
+
+ default:
+ return false;
+ }
+}
+
+/* Returns true if ARG is an absorbing element for operation CODE. */
+
+static bool
+absorbing_element_p (tree_code code, tree arg)
+{
+ switch (code)
+ {
+ case BIT_IOR_EXPR:
+ return integer_all_onesp (arg);
+
+ case MULT_EXPR:
+ case BIT_AND_EXPR:
+ return integer_zerop (arg);
+
+ default:
+ return false;
+ }
+}
+
/* The function value_replacement does the main work of doing the value
replacement. Return non-zero if the replacement is done. Otherwise return
0. If we remove the middle basic block, return 2.
BB is the basic block where the replacement is going to be done on. ARG0
is argument 0 from the PHI. Likewise for ARG1. */
static int
value_replacement (basic_block cond_bb, basic_block middle_bb,
edge e0, edge e1, gimple phi,
tree arg0, tree arg1)
@@ -676,23 +735,21 @@ value_replacement (basic_block cond_bb,
enum tree_code code;
bool emtpy_or_with_defined_p = true;
/* If the type says honor signed zeros we cannot do this
optimization. */
if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1))))
return 0;
/* If there is a statement in MIDDLE_BB that defines one of the PHI
arguments, then adjust arg0 or arg1. */
- gsi = gsi_after_labels (middle_bb);
- if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi)))
- gsi_next_nondebug (&gsi);
+ gsi = gsi_start_nondebug_after_labels_bb (middle_bb);
while (!gsi_end_p (gsi))
{
gimple stmt = gsi_stmt (gsi);
tree lhs;
gsi_next_nondebug (&gsi);
if (!is_gimple_assign (stmt))
{
emtpy_or_with_defined_p = false;
continue;
}
@@ -774,20 +831,69 @@ value_replacement (basic_block cond_bb,
print_generic_expr (dump_file, gimple_phi_result (phi), 0);
fprintf (dump_file, " reduced for COND_EXPR in block %d to ",
cond_bb->index);
print_generic_expr (dump_file, arg, 0);
fprintf (dump_file, ".\n");
}
return 1;
}
}
+
+ /* Now optimize (x != 0) ? x + y : y to just y.
+ The following condition is too restrictive, there can easily be another
+ stmt in middle_bb, for instance a CONVERT_EXPR for the second argument. */
+ gimple assign = last_and_only_stmt (middle_bb);
+ if (!assign || gimple_code (assign) != GIMPLE_ASSIGN
+ || gimple_assign_rhs_class (assign) != GIMPLE_BINARY_RHS
+ || (!INTEGRAL_TYPE_P (TREE_TYPE (arg0))
+ && !POINTER_TYPE_P (TREE_TYPE (arg0))))
+ return 0;
+
+ /* Size-wise, this is always profitable. */
+ if (optimize_bb_for_speed_p (cond_bb)
+ /* The special case is useless if it has a low probability. */
+ && profile_status_for_fn (cfun) != PROFILE_ABSENT
+ && EDGE_PRED (middle_bb, 0)->probability < PROB_EVEN
+ /* If assign is cheap, there is no point avoiding it. */
+ && estimate_num_insns (assign, &eni_time_weights)
+ >= 3 * estimate_num_insns (cond, &eni_time_weights))
+ return 0;
+
+ tree lhs = gimple_assign_lhs (assign);
+ tree rhs1 = gimple_assign_rhs1 (assign);
+ tree rhs2 = gimple_assign_rhs2 (assign);
+ enum tree_code code_def = gimple_assign_rhs_code (assign);
+ tree cond_lhs = gimple_cond_lhs (cond);
+ tree cond_rhs = gimple_cond_rhs (cond);
+
+ if (((code == NE_EXPR && e1 == false_edge)
+ || (code == EQ_EXPR && e1 == true_edge))
+ && arg0 == lhs
+ && ((arg1 == rhs1
+ && operand_equal_for_phi_arg_p (rhs2, cond_lhs)
+ && neutral_element_p (code_def, cond_rhs, true))
+ || (arg1 == rhs2
+ && operand_equal_for_phi_arg_p (rhs1, cond_lhs)
+ && neutral_element_p (code_def, cond_rhs, false))
+ || (operand_equal_for_phi_arg_p (arg1, cond_rhs)
+ && (operand_equal_for_phi_arg_p (rhs2, cond_lhs)
+ || operand_equal_for_phi_arg_p (rhs1, cond_lhs))
+ && absorbing_element_p (code_def, cond_rhs))))
+ {
+ gsi = gsi_for_stmt (cond);
+ gimple_stmt_iterator gsi_from = gsi_for_stmt (assign);
+ gsi_move_before (&gsi_from, &gsi);
+ replace_phi_edge_with_variable (cond_bb, e1, phi, lhs);
+ return 2;
+ }
+
return 0;
}
/* 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. */
static bool