[PATCH olang v2 3/4] codegen: x86_64: add support to emit if statements

[Johnny Richard <johnny@johnnyrichard.com>]

Signed-off-by: Johnny Richard <johnny@johnnyrichard.com>
---
 src/codegen_linux_x86_64.c                    | 63 ++++++++++++++-----
 tests/integration/tests/0020_if_statement.ol  |  3 +
 .../tests/0021_if_statement_failed.ol         | 24 +++++++
 3 files changed, 76 insertions(+), 14 deletions(-)
 create mode 100644 tests/integration/tests/0021_if_statement_failed.ol

diff --git a/src/codegen_linux_x86_64.c b/src/codegen_linux_x86_64.c
index 64ec0e0..3b509ba 100644
--- a/src/codegen_linux_x86_64.c
+++ b/src/codegen_linux_x86_64.c
@@ -299,26 +299,61 @@ codegen_linux_x86_64_emit_expression(FILE *out, ast_node_t *expr_node)
             assert(0 && "unsupported expression");
     }
 }
+static void
+codegen_linux_x86_64_emit_block(FILE *out, ast_block_t *block)
+{
+
+    size_t nodes_len = list_size(block->nodes);
+
+    for (size_t i = 0; i < nodes_len; ++i) {
+        ast_node_t *node = list_get(block->nodes, i)->value;
+        switch (node->kind) {
+            case AST_NODE_RETURN_STMT: {
+                ast_return_stmt_t return_stmt = node->as_return_stmt;
+
+                ast_node_t *expr = return_stmt.data;
+
+                codegen_linux_x86_64_emit_expression(out, expr);
+
+                fprintf(out, "    ret\n");
+
+                break;
+            }
+            case AST_NODE_IF_STMT: {
+                ast_if_stmt_t if_stmt = node->as_if_stmt;
+
+                ast_node_t *cond = if_stmt.cond;
+                ast_node_t *then = if_stmt.then;
+
+                size_t end_if_label = codegen_linux_x86_64_get_next_label();
+
+                codegen_linux_x86_64_emit_expression(out, cond);
+                fprintf(out, "    jnz .L%ld\n", end_if_label);
+
+                assert(then->kind == AST_NODE_BLOCK && "invalid if-then block");
+                ast_block_t then_block = then->as_block;
+
+                codegen_linux_x86_64_emit_block(out, &then_block);
+
+                fprintf(out, ".L%ld:\n", end_if_label);
+                break;
+            }
+            default: {
+                assert(0 && "unsupported block statement");
+                break;
+            }
+        }
+    }
+}
 
 static void
 codegen_linux_x86_64_emit_function(FILE *out, ast_fn_definition_t *fn)
 {
     ast_node_t *block_node = fn->block;
+    fprintf(out, "" SV_FMT ":\n", SV_ARG(fn->identifier));
+
     assert(block_node->kind == AST_NODE_BLOCK);
     ast_block_t block = block_node->as_block;
 
-    assert(list_size(block.nodes) == 1);
-
-    list_item_t *nodes_item = list_get(block.nodes, 0);
-    ast_node_t *return_node = nodes_item->value;
-    assert(return_node->kind == AST_NODE_RETURN_STMT);
-    ast_return_stmt_t return_stmt = return_node->as_return_stmt;
-
-    ast_node_t *expr = return_stmt.data;
-
-    fprintf(out, "" SV_FMT ":\n", SV_ARG(fn->identifier));
-
-    codegen_linux_x86_64_emit_expression(out, expr);
-
-    fprintf(out, "    ret\n");
+    codegen_linux_x86_64_emit_block(out, &block);
 }
diff --git a/tests/integration/tests/0020_if_statement.ol b/tests/integration/tests/0020_if_statement.ol
index ef3cd36..d48122f 100644
--- a/tests/integration/tests/0020_if_statement.ol
+++ b/tests/integration/tests/0020_if_statement.ol
@@ -20,6 +20,9 @@ fn main(): u32 {
   return 1
 }
 
+# TEST test_compile(exit_code=0)
+# TEST test_run_binary(exit_code=0)
+#
 # TEST test_contains_tokens WITH
 # ./tests/0020_if_statement.ol:17:3: <if>
 # END
diff --git a/tests/integration/tests/0021_if_statement_failed.ol b/tests/integration/tests/0021_if_statement_failed.ol
new file mode 100644
index 0000000..4bc2838
--- /dev/null
+++ b/tests/integration/tests/0021_if_statement_failed.ol
@@ -0,0 +1,24 @@
+# Copyright (C) 2024 olang mantainers
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+fn main(): u32 {
+  if 0 == 1 {
+    return 1
+  }
+  return 0
+}
+
+# TEST test_compile(exit_code=0)
+# TEST test_run_binary(exit_code=0)
-- 
2.46.0