Initial project import

tools/v/vlib/v3/ssa/optimize/cfg.v

@@ -0,0 +1,95 @@
+module optimize
+
+import v3.ssa
+
+fn arr_contains(arr []int, val int) bool {
+	for v in arr {
+		if v == val {
+			return true
+		}
+	}
+	return false
+}
+
+fn build_cfg(mut m ssa.Module) {
+	n_blocks := m.blocks.len
+	n_values := m.values.len
+
+	for bi in 0 .. n_blocks {
+		mut blk := m.blocks[bi]
+		blk.succs = []
+		blk.preds = []
+		m.blocks[bi] = blk
+	}
+
+	for fi in 0 .. m.funcs.len {
+		for blk_id in m.funcs[fi].blocks {
+			blk := m.blocks[blk_id]
+			if blk.instrs.len == 0 {
+				continue
+			}
+			term_val_id := blk.instrs.last()
+			if term_val_id < 0 || term_val_id >= n_values {
+				continue
+			}
+			term_val := m.values[term_val_id]
+			if term_val.kind != .instruction {
+				continue
+			}
+			term := m.instrs[term_val.index]
+
+			match term.op {
+				.br {
+					if term.operands.len >= 3 {
+						for oi in 1 .. 3 {
+							s := int(term.operands[oi])
+							if s >= 0 && s < n_blocks && !arr_contains(m.blocks[blk_id].succs, s) {
+								mut b := m.blocks[blk_id]
+								b.succs << s
+								m.blocks[blk_id] = b
+							}
+						}
+					}
+				}
+				.jmp {
+					if term.operands.len >= 1 {
+						s := int(term.operands[0])
+						if s >= 0 && s < n_blocks {
+							mut b := m.blocks[blk_id]
+							b.succs << s
+							m.blocks[blk_id] = b
+						}
+					}
+				}
+				.switch_ {
+					// switch_ cond, default_blk, [case_val, blk]...
+					if term.operands.len >= 2 {
+						s := int(term.operands[1])
+						if s >= 0 && s < n_blocks && !arr_contains(m.blocks[blk_id].succs, s) {
+							mut b := m.blocks[blk_id]
+							b.succs << s
+							m.blocks[blk_id] = b
+						}
+						for oi := 3; oi < term.operands.len; oi += 2 {
+							cs := int(term.operands[oi])
+							if cs >= 0 && cs < n_blocks && !arr_contains(m.blocks[blk_id].succs, cs) {
+								mut b := m.blocks[blk_id]
+								b.succs << cs
+								m.blocks[blk_id] = b
+							}
+						}
+					}
+				}
+				else {}
+			}
+
+			for s in m.blocks[blk_id].succs {
+				if s >= 0 && s < n_blocks && !arr_contains(m.blocks[s].preds, blk_id) {
+					mut b := m.blocks[s]
+					b.preds << blk_id
+					m.blocks[s] = b
+				}
+			}
+		}
+	}
+}