cleanup space generation logic and make it more robust for union constructs

[libfirm] / ir / opt / boolopt.c

diff --git a/ir/opt/boolopt.c b/ir/opt/boolopt.c
index 5ddcd94..ca97dc4 100644 (file)
--- a/ir/opt/boolopt.c
+++ b/ir/opt/boolopt.c
@@ -264,7 +264,12 @@ static void collect_phis(ir_node *node, void *env)
        }
 }
 
-ir_node *skip_empty_block(ir_node *node)
+/**
+ * If node is a Jmp in a block containing no pinned instruction
+ * and having only one predecessor, skip the block and return its
+ * cf predecessor, else the node itself.
+ */
+static ir_node *skip_empty_block(ir_node *node)
 {
        ir_node      *block;
 
@@ -314,22 +319,22 @@ restart:
                if(!is_Proj(lower_cf))
                        continue;
 
-               lower_block = get_nodes_block(lower_cf);
-               if(get_Block_n_cfgpreds(lower_block) != 1)
-                       continue;
-
                cond = get_Proj_pred(lower_cf);
                if(!is_Cond(cond))
                        continue;
 
-               cond_selector = get_Cond_selector(cond);
-               if(get_irn_mode(cond_selector) != mode_b)
+               lower_block = get_nodes_block(cond);
+               if(get_Block_n_cfgpreds(lower_block) != 1)
                        continue;
 
                /* the block must not produce any side-effects */
                if(get_Block_mark(lower_block))
                        continue;
 
+               cond_selector = get_Cond_selector(cond);
+               if(get_irn_mode(cond_selector) != mode_b)
+                       continue;
+
                lower_pred = get_Block_cfgpred_block(lower_block, 0);
 
                for(i2 = 0; i2 < n_cfgpreds; ++i2) {
@@ -362,7 +367,7 @@ restart:
                                continue;
 
                        /* normalize pncs: we need the true case to jump into the
-                        * common block */
+                        * common block (ie. conjunctive normal form) */
                        irg = current_ir_graph;
                        if(get_Proj_proj(lower_cf) == pn_Cond_false) {
                                if(cpair.proj_lo == cond_selector) {