Initial support for converting QBE SIL to SSA

Author: ChAoSUnItY

example.ssa

@@ -1,19 +1,12 @@
-function w $strlen(w %str) {
-  %t3 =w copy 0
-  %i =w copy %t3
-  @L_begin_0
-  %t4 =w copy 1
-  %t5 =w mul %i, %t4
-  %t6 =w add %str, %t5
-  %t7 =b loadb %t6
-  jnz %t7, @L_then_0, @L_0
-  @L_then_0
-  %t8 =w copy 1
-  %i =w add %i, %t8
-  %t9 =w copy -1
-  %t10 =w add %i, %t9
-  @L_1
-  jmp @L_begin_0
-  @L_0
-  ret %i
+function w $main() {
+  %a =w copy 1
+  %t =w alloc 4
+  jnz %a, @L1, @L2
+@L1
+  %t =w add %t, %t
+  jmp @L3
+@L2
+  %t =w copy 1
+@L3
+  ret %t
 }

src/globals.c

@@ -59,6 +59,7 @@ arena_t *BLOCK_ARENA;
 /* BB_ARENA is responsible for basic_block_t / ph2_ir_t allocation */
 arena_t *BB_ARENA;
 
+int global_var_idx = 0;
 int bb_label_idx = 0;
 
 ph2_ir_t **PH2_IR_FLATTEN;
@@ -87,6 +88,9 @@ int elf_header_len = 0x54; /* ELF fixed: 0x34 + 1 * 0x20 */
 int elf_code_start;
 int elf_data_start;
 
+void fatal(char *msg);
+void error(char *msg);
+
 /**
  * arena_block_create() - Creates a new arena block with given capacity.
  * The created arena block is guaranteed to be zero-initialized.
@@ -521,6 +525,85 @@ block_t *add_block(block_t *parent, func_t *func, macro_t *macro)
     return blk;
 }
 
+char *gen_name_to(char *buf)
+{
+    sprintf(buf, ".t%d", global_var_idx++);
+    return buf;
+}
+
+var_t *init_var(var_t *var)
+{
+    var->consumed = -1;
+    var->base = var;
+    return var;
+}
+
+var_t *require_var(block_t *blk)
+{
+    var_list_t *var_list = &blk->locals;
+
+    if (var_list->size >= var_list->capacity) {
+        var_list->capacity <<= 1;
+
+        var_t **new_locals =
+            arena_alloc(BLOCK_ARENA, var_list->capacity * sizeof(var_t *));
+        memcpy(new_locals, var_list->elements,
+               var_list->size * sizeof(var_t *));
+        var_list->elements = new_locals;
+    }
+
+    var_t *var = arena_alloc(BLOCK_ARENA, sizeof(var_t));
+    var_list->elements[var_list->size++] = var;
+    init_var(var);
+    var->type = TY_int;
+    return var;
+}
+
+var_t *require_typed_var(block_t *blk, type_t *type)
+{
+    if (!type)
+        error("Type must not be NULL");
+
+    var_t *var = require_var(blk);
+    var->type = type;
+    return var;
+}
+
+var_t *require_typed_ptr_var(block_t *blk, type_t *type, int ptr)
+{
+    var_t *var = require_typed_var(blk, type);
+    var->is_ptr = ptr;
+    return var;
+}
+
+var_t *require_ref_var(block_t *blk, type_t *type, int ptr)
+{
+    if (!type)
+        error("Cannot reference variable from NULL type");
+
+    var_t *var = require_typed_var(blk, type);
+    var->is_ptr = ptr + 1;
+    return var;
+}
+
+var_t *require_deref_var(block_t *blk, type_t *type, int ptr)
+{
+    if (!type)
+        error("Cannot dereference variable from NULL type");
+
+    /* Allowing integer dereferencing */
+    if (!ptr && type->base_type != TYPE_struct &&
+        type->base_type != TYPE_typedef)
+        return require_var(blk);
+
+    if (!ptr)
+        error("Cannot dereference from non-pointer typed variable");
+
+    var_t *var = require_typed_var(blk, type);
+    var->is_ptr = ptr - 1;
+    return var;
+}
+
 void add_alias(char *alias, char *value)
 {
     alias_t *al = hashmap_get(ALIASES_MAP, alias);