extern void tb_procedure(struct procedure* proc);
extern void tb_regvar(struct procedure* proc, arith offset, int size, int type, int priority);
+extern void pass_convert_locals_to_ssa(struct procedure* proc);
extern void pass_convert_stack_ops(struct procedure* proc);
-extern void pass_remove_dead_blocks(struct procedure* proc);
extern void pass_eliminate_trivial_blocks(struct procedure* proc);
+extern void pass_group_irs(struct procedure* proc);
extern void pass_instruction_selector(struct procedure* proc);
extern void pass_promote_float_ops(struct procedure* proc);
-extern void pass_group_irs(struct procedure* proc);
-extern void pass_convert_locals_to_ssa(struct procedure* proc);
+extern void pass_remove_dead_blocks(struct procedure* proc);
+extern void pass_split_critical_edges(struct procedure* proc);
#endif
--- /dev/null
+#include "mcg.h"
+
+/* Insert empty nodes at certain places in the basic block graph so that when
+ * we convert out of SSA form, we have somewhere to insert copies. This is
+ * necessary for correctness in certain circumstances. The best explanation of
+ * why I've found is here, starting at the bottom of page 23.
+ *
+ * Briggs, Preston, et al.
+ * "Practical improvements to the construction and destruction of static single assignment form."
+ * Software-Practice and experience 28.8 (1998): 859-882.
+ *
+ * http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.25.749
+ */
+
+static struct procedure* current_proc;
+
+struct rewrite_params
+{
+ struct basicblock* find;
+ struct basicblock* replace;
+};
+
+static bool find_replace_cb(struct ir* ir, void* user)
+{
+ struct rewrite_params* rwp = user;
+
+ if ((ir->opcode == IR_BLOCK) && (ir->u.bvalue == rwp->find))
+ ir->u.bvalue = rwp->replace;
+
+ return false;
+}
+
+static void split_edge(struct basicblock* source, struct basicblock* sink)
+{
+ int i;
+ struct rewrite_params rwp;
+ struct basicblock* bb = bb_get(NULL);
+
+ array_append(&bb->irs,
+ new_ir1(
+ IR_JUMP, 0,
+ new_bbir(sink)
+ )
+ );
+
+ rwp.find = sink;
+ rwp.replace = bb;
+
+ for (i=0; i<source->irs.count; i++)
+ ir_walk(source->irs.item[i], find_replace_cb, &rwp);
+
+ array_remove(&source->nexts, sink);
+ array_append(&source->nexts, bb);
+
+ array_append(&bb->prevs, source);
+ array_append(&bb->nexts, sink);
+
+ array_remove(&sink->prevs, source);
+ array_append(&sink->prevs, bb);
+
+ array_append(¤t_proc->blocks, bb);
+}
+
+static void consider_edges_leading_to(struct basicblock* bb)
+{
+ if (bb->prevs.count > 1)
+ {
+ int i;
+
+ for (i=0; i<bb->prevs.count; i++)
+ {
+ struct basicblock* prev = bb->prevs.item[i];
+ if (prev->nexts.count > 1)
+ split_edge(prev, bb);
+ }
+ }
+}
+
+void pass_split_critical_edges(struct procedure* proc)
+{
+ int i;
+
+ current_proc = proc;
+
+ for (i=0; i<proc->blocks.count; i++)
+ consider_edges_leading_to(proc->blocks.item[i]);
+}
+
+/* vim: set sw=4 ts=4 expandtab : */
+
+
bb->is_fake ? "FAKE " : "",
bb->name);
- for (int j=0; j<bb->irs.count; j++)
+ if (bb->prevs.count > 0)
+ {
+ tracef(k, "%c: FROM:", k);
+ for (j=0; j<bb->prevs.count; j++)
+ tracef(k, " %s", bb->prevs.item[j]->name);
+ tracef(k, "\n");
+ }
+
+ if (bb->nexts.count > 0)
+ {
+ tracef(k, "%c: TO:", k);
+ for (j=0; j<bb->nexts.count; j++)
+ tracef(k, " %s", bb->nexts.item[j]->name);
+ tracef(k, "\n");
+ }
+
+ for (j=0; j<bb->irs.count; j++)
ir_print(k, bb->irs.item[j]);
}
}
print_blocks('3', proc);
pass_convert_locals_to_ssa(proc);
print_blocks('4', proc);
- pass_promote_float_ops(proc);
+ pass_split_critical_edges(proc);
print_blocks('5', proc);
+ pass_promote_float_ops(proc);
+ print_blocks('6', proc);
pass_instruction_selector(proc);