diff options
Diffstat (limited to 'gcc/tree-ssa-dom.c')
| -rw-r--r-- | gcc/tree-ssa-dom.c | 28 |
1 files changed, 20 insertions, 8 deletions
diff --git a/gcc/tree-ssa-dom.c b/gcc/tree-ssa-dom.c index 494b472..407a4ef 100644 --- a/gcc/tree-ssa-dom.c +++ b/gcc/tree-ssa-dom.c @@ -32,6 +32,7 @@ along with GCC; see the file COPYING3. If not see #include "cfgloop.h" #include "gimple-fold.h" #include "tree-eh.h" +#include "tree-inline.h" #include "gimple-iterator.h" #include "tree-cfg.h" #include "tree-into-ssa.h" @@ -776,16 +777,27 @@ record_temporary_equivalences (edge e, /* Record the simple NAME = VALUE equivalence. */ tree rhs = edge_info->rhs; - record_equality (lhs, rhs, const_and_copies); - /* We already recorded that LHS = RHS, with canonicalization, - value chain following, etc. + /* If this is a SSA_NAME = SSA_NAME equivalence and one operand is + cheaper to compute than the other, then set up the equivalence + such that we replace the expensive one with the cheap one. - We also want to record RHS = LHS, but without any canonicalization - or value chain following. */ - if (TREE_CODE (rhs) == SSA_NAME) - const_and_copies->record_const_or_copy_raw (rhs, lhs, - SSA_NAME_VALUE (rhs)); + If they are the same cost to compute, then do not record anything. */ + if (TREE_CODE (lhs) == SSA_NAME && TREE_CODE (rhs) == SSA_NAME) + { + gimple *rhs_def = SSA_NAME_DEF_STMT (rhs); + int rhs_cost = estimate_num_insns (rhs_def, &eni_size_weights); + + gimple *lhs_def = SSA_NAME_DEF_STMT (lhs); + int lhs_cost = estimate_num_insns (lhs_def, &eni_size_weights); + + if (rhs_cost > lhs_cost) + record_equality (rhs, lhs, const_and_copies); + else if (rhs_cost < lhs_cost) + record_equality (lhs, rhs, const_and_copies); + } + else + record_equality (lhs, rhs, const_and_copies); /* If LHS is an SSA_NAME and RHS is a constant integer and LHS was set via a widening type conversion, then we may be able to record |