diff options
Diffstat (limited to 'gcc/tree-ssa-loop-niter.c')
| -rw-r--r-- | gcc/tree-ssa-loop-niter.c | 27 |
1 files changed, 17 insertions, 10 deletions
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c index d5eaa33..de206471 100644 --- a/gcc/tree-ssa-loop-niter.c +++ b/gcc/tree-ssa-loop-niter.c @@ -2521,7 +2521,8 @@ chain_of_csts_start (struct loop *loop, tree x) * the derivation of X consists only from operations with constants * the initial value of the phi node is constant * the value of the phi node in the next iteration can be derived from the - value in the current iteration by a chain of operations with constants. + value in the current iteration by a chain of operations with constants, + or is also a constant If such phi node exists, it is returned, otherwise NULL is returned. */ @@ -2541,13 +2542,11 @@ get_base_for (struct loop *loop, tree x) init = PHI_ARG_DEF_FROM_EDGE (phi, loop_preheader_edge (loop)); next = PHI_ARG_DEF_FROM_EDGE (phi, loop_latch_edge (loop)); - if (TREE_CODE (next) != SSA_NAME) - return NULL; - if (!is_gimple_min_invariant (init)) return NULL; - if (chain_of_csts_start (loop, next) != phi) + if (TREE_CODE (next) == SSA_NAME + && chain_of_csts_start (loop, next) != phi) return NULL; return phi; @@ -2556,6 +2555,7 @@ get_base_for (struct loop *loop, tree x) /* Given an expression X, then * if X is NULL_TREE, we return the constant BASE. + * if X is a constant, we return the constant X. * otherwise X is a SSA name, whose value in the considered loop is derived by a chain of operations with constant from a result of a phi node in the header of the loop. Then we return value of X when the value of the @@ -2570,6 +2570,8 @@ get_val_for (tree x, tree base) if (!x) return base; + else if (is_gimple_min_invariant (x)) + return x; stmt = SSA_NAME_DEF_STMT (x); if (gimple_code (stmt) == GIMPLE_PHI) @@ -2584,11 +2586,9 @@ get_val_for (tree x, tree base) return get_val_for (gimple_assign_rhs1 (stmt), base); else if (gimple_assign_rhs_class (stmt) == GIMPLE_UNARY_RHS && TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME) - { - return fold_build1 (gimple_assign_rhs_code (stmt), - gimple_expr_type (stmt), - get_val_for (gimple_assign_rhs1 (stmt), base)); - } + return fold_build1 (gimple_assign_rhs_code (stmt), + gimple_expr_type (stmt), + get_val_for (gimple_assign_rhs1 (stmt), base)); else if (gimple_assign_rhs_class (stmt) == GIMPLE_BINARY_RHS) { tree rhs1 = gimple_assign_rhs1 (stmt); @@ -2687,6 +2687,7 @@ loop_niter_by_eval (struct loop *loop, edge exit) for (j = 0; j < 2; j++) { + aval[j] = val[j]; val[j] = get_val_for (next[j], val[j]); if (!is_gimple_min_invariant (val[j])) { @@ -2694,6 +2695,12 @@ loop_niter_by_eval (struct loop *loop, edge exit) return chrec_dont_know; } } + + /* If the next iteration would use the same base values + as the current one, there is no point looping further, + all following iterations will be the same as this one. */ + if (val[0] == aval[0] && val[1] == aval[1]) + break; } fold_undefer_and_ignore_overflow_warnings (); |