diff options
Diffstat (limited to 'gcc/tree-ssa-ccp.c')
| -rw-r--r-- | gcc/tree-ssa-ccp.c | 31 |
1 files changed, 30 insertions, 1 deletions
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c index 5e30588..4542403 100644 --- a/gcc/tree-ssa-ccp.c +++ b/gcc/tree-ssa-ccp.c @@ -229,6 +229,7 @@ typedef enum static prop_value_t *const_val; static void canonicalize_float_value (prop_value_t *); +static bool ccp_fold_stmt (gimple_stmt_iterator *); /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */ @@ -724,7 +725,7 @@ ccp_finalize (void) do_dbg_cnt (); /* Perform substitutions based on the known constant values. */ - something_changed = substitute_and_fold (const_val, NULL); + something_changed = substitute_and_fold (const_val, ccp_fold_stmt); free (const_val); const_val = NULL; @@ -1472,6 +1473,34 @@ evaluate_stmt (gimple stmt) return val; } +/* Fold the stmt at *GSI with CCP specific information that propagating + and regular folding does not catch. */ + +static bool +ccp_fold_stmt (gimple_stmt_iterator *gsi) +{ + gimple stmt = gsi_stmt (*gsi); + prop_value_t val; + + if (gimple_code (stmt) != GIMPLE_COND) + return false; + + /* Statement evaluation will handle type mismatches in constants + more gracefully than the final propagation. This allows us to + fold more conditionals here. */ + val = evaluate_stmt (stmt); + if (val.lattice_val != CONSTANT + || TREE_CODE (val.value) != INTEGER_CST) + return false; + + if (integer_zerop (val.value)) + gimple_cond_make_false (stmt); + else + gimple_cond_make_true (stmt); + + return true; +} + /* Visit the assignment statement STMT. Set the value of its LHS to the value computed by the RHS and store LHS in *OUTPUT_P. If STMT creates virtual definitions, set the value of each new name to that |