feat: support seven or more parameters/arguments

5 files changed, 99 insertions, 37 deletions

diff --git a/src/codegen.c b/src/codegen.c
index 97a9209..0b586be 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -56,7 +56,7 @@ static const char* param_reg(int n) {
 static void codegen_func_prologue(CodeGen* g, AstNode* ast) {
     fprintf(g->out, "  push rbp\n");
     fprintf(g->out, "  mov rbp, rsp\n");
-    for (int i = 0; i < ast->node_params->node_len; ++i) {
+    for (int i = 0; i < ast->node_params->node_len && i < 6; ++i) {
         fprintf(g->out, "  push %s\n", param_reg(i));
     }
     // Note: rsp must be aligned to 8.
@@ -363,6 +363,17 @@ static void codegen_assign_expr(CodeGen* g, AstNode* ast) {
     }
 }
 
+static void codegen_args(CodeGen* g, AstNode* args) {
+    // Evaluate arguments in the reverse order (right to left).
+    for (int i = args->node_len - 1; i >= 0; --i) {
+        AstNode* arg = &args->node_items[i];
+        codegen_expr(g, arg, GenMode_rval);
+    }
+    for (int i = 0; i < args->node_len && i < 6; ++i) {
+        fprintf(g->out, "  pop %s\n", param_reg(i));
+    }
+}
+
 static void codegen_func_call(CodeGen* g, AstNode* ast) {
     const char* func_name = ast->name;
 
@@ -395,41 +406,41 @@ static void codegen_func_call(CodeGen* g, AstNode* ast) {
     }
 
     AstNode* args = ast->node_args;
-    // Evaluate arguments in the reverse order (right to left).
-    for (int i = args->node_len - 1; i >= 0; --i) {
-        AstNode* arg = &args->node_items[i];
-        codegen_expr(g, arg, GenMode_rval);
-    }
-    for (int i = 0; i < args->node_len && i < 6; ++i) {
-        fprintf(g->out, "  pop %s\n", param_reg(i));
-    }
+    int overflow_args_count = args->node_len <= 6 ? 0 : args->node_len - 6;
 
     int label = codegen_new_label(g);
 
     fprintf(g->out, "  mov rax, rsp\n");
+    if (overflow_args_count % 2 == 1) {
+        fprintf(g->out, "  add rax, 8\n");
+    }
     fprintf(g->out, "  and rax, 15\n");
     fprintf(g->out, "  cmp rax, 0\n");
     fprintf(g->out, "  je .Laligned%d\n", label);
 
-    fprintf(g->out, "  mov rax, 0\n");
     fprintf(g->out, "  sub rsp, 8\n");
+    codegen_args(g, args);
+    fprintf(g->out, "  mov rax, 0\n");
     fprintf(g->out, "  call %s\n", func_name);
     fprintf(g->out, "  add rsp, 8\n");
-    fprintf(g->out, "  push rax\n");
 
     fprintf(g->out, "  jmp .Lend%d\n", label);
     fprintf(g->out, ".Laligned%d:\n", label);
 
+    codegen_args(g, args);
     fprintf(g->out, "  mov rax, 0\n");
     fprintf(g->out, "  call %s\n", func_name);
-    fprintf(g->out, "  push rax\n");
 
     fprintf(g->out, ".Lend%d:\n", label);
+    // Pop pass-by-stack arguments.
+    for (int i = 0; i < overflow_args_count; i++) {
+        fprintf(g->out, "  add rsp, 8\n");
+    }
+    fprintf(g->out, "  push rax\n");
 }
 
 static void codegen_lvar(CodeGen* g, AstNode* ast, GenMode gen_mode) {
-    fprintf(g->out, "  mov rax, rbp\n");
-    fprintf(g->out, "  sub rax, %d\n", ast->node_stack_offset);
+    fprintf(g->out, "  lea rax, %d[rbp]\n", -ast->node_stack_offset);
     fprintf(g->out, "  push rax\n");
     if (gen_mode == GenMode_rval) {
         codegen_lval2rval(g, ast->ty);
diff --git a/src/parse.c b/src/parse.c
index f336c0c..195a3b0 100644
--- a/src/parse.c
+++ b/src/parse.c
@@ -230,25 +230,33 @@ static int find_lvar(Parser* p, const char* name) {
 }
 
 static int calc_stack_offset(Parser* p, Type* ty, bool is_param) {
-    int align;
     if (is_param) {
         if (8 < type_sizeof(ty) || 8 < type_alignof(ty)) {
             fatal_error("too large");
         }
-        align = 8;
-    } else {
-        align = type_alignof(ty);
-    }
-
-    int offset;
-    if (p->lvars.len == 0) {
-        offset = 0;
+        int offset;
+        if (p->lvars.len == 0) {
+            offset = 0;
+        } else {
+            offset = p->lvars.data[p->lvars.len - 1].stack_offset;
+        }
+        if (offset < 0) {
+            return offset - 8;
+        } else if (offset >= 6 * 8) {
+            return -16;
+        } else {
+            return offset + 8;
+        }
     } else {
-        offset = p->lvars.data[p->lvars.len - 1].stack_offset;
+        int offset = 0;
+        for (size_t i = 0; i < p->lvars.len; i++) {
+            int o = p->lvars.data[i].stack_offset;
+            if (offset < o) {
+                offset = o;
+            }
+        }
+        return to_aligned(offset + type_sizeof(ty), type_alignof(ty));
     }
-
-    offset += type_sizeof(ty);
-    return to_aligned(offset, align);
 }
 
 static int add_lvar(Parser* p, const char* name, Type* ty, bool is_param) {
@@ -448,9 +456,6 @@ static AstNode* parse_arg_list(Parser* p) {
             break;
         }
     }
-    if (list->node_len > 6) {
-        fatal_error("too many arguments");
-    }
     return list;
 }
 
@@ -1008,9 +1013,6 @@ static AstNode* parse_parameter_type_list(Parser* p) {
         has_void |= params->node_items[i].ty->kind == TypeKind_void;
     }
 
-    if (params->node_len > 6) {
-        fatal_error("too many parameters");
-    }
     if (has_void) {
         if (params->node_len != 1) {
             fatal_error("invalid use of void param");
@@ -1464,8 +1466,14 @@ static AstNode* parse_func_def(Parser* p, AstNode* decls) {
     if (p->lvars.len == 0) {
         func->node_stack_size = 0;
     } else {
-        func->node_stack_size =
-            p->lvars.data[p->lvars.len - 1].stack_offset + type_sizeof(p->lvars.data[p->lvars.len - 1].ty);
+        int stack_size = 0;
+        for (size_t i = 0; i < p->lvars.len; i++) {
+            int s = p->lvars.data[i].stack_offset + type_sizeof(p->lvars.data[i].ty);
+            if (stack_size < s) {
+                stack_size = s;
+            }
+        }
+        func->node_stack_size = stack_size;
     }
     return func;
 }
diff --git a/tests/function_basics.c b/tests/function_basics.c
index f02384c..1d79ad7 100644
--- a/tests/function_basics.c
+++ b/tests/function_basics.c
@@ -1,5 +1,8 @@
 #include <helpers.h>
 
+int sprintf(char*, const char*, ...);
+int strcmp(const char*, const char*);
+
 int foo() {
     int i;
     int ret;
@@ -38,6 +41,36 @@ int f6(int a, int b, int c, int d, int e, int f) {
     return f;
 }
 
+int f7(int select, int a, int b, int c, int d, int e, int f, int g, int h, int i, int j) {
+    switch (select) {
+    case 0:
+        return a;
+    case 1:
+        return b;
+    case 2:
+        return c;
+    case 3:
+        return d;
+    case 4:
+        return e;
+    case 5:
+        return f;
+    case 6:
+        return g;
+    case 7:
+        return h;
+    case 8:
+        return i;
+    case 9:
+        return j;
+    }
+}
+
+char* f8(char* buf, int a, int b, int c, int d, int e, int f, int g, int h, int i, int j) {
+    sprintf(buf, "%d,%d,%d,%d,%d,%d,%d,%d,%d,%d", a, b, c, d, e, f, g, h, i, j);
+    return buf;
+}
+
 int main() {
     ASSERT_EQ(66, foo());
     ASSERT_EQ(10, 10 * f(1, 2, 3, 4, 5, 6));
@@ -46,4 +79,14 @@ int main() {
     ASSERT_EQ(40, 10 * f4(1, 2, 3, 4, 5, 6));
     ASSERT_EQ(50, 10 * f5(1, 2, 3, 4, 5, 6));
     ASSERT_EQ(60, 10 * f6(1, 2, 3, 4, 5, 6));
+
+    ASSERT_EQ(1, f7(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
+    ASSERT_EQ(2, f7(1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
+    ASSERT_EQ(6, f7(5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
+    ASSERT_EQ(7, f7(6, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
+    ASSERT_EQ(8, f7(7, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
+    ASSERT_EQ(10, f7(9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
+
+    char buf[100];
+    ASSERT_EQ(0, strcmp("1,2,3,4,5,6,7,8,9,10", f8(buf, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)));
 }
diff --git a/tests/helpers.h b/tests/helpers.h
index f8affe7..39274e4 100644
--- a/tests/helpers.h
+++ b/tests/helpers.h
@@ -10,7 +10,7 @@ extern FILE* stderr;
 #define ASSERT(a, file, line) \
     do { \
         if (!(a)) { \
-            fprintf(stderr, "%s:%d: assert failed", file, line); \
+            fprintf(stderr, "%s:%d: assert failed\n", file, line); \
             exit(1); \
         } \
     } while (0)
diff --git a/tests/run.sh b/tests/run.sh
index 0835d9a..6b3bb00 100644
--- a/tests/run.sh
+++ b/tests/run.sh
@@ -14,7 +14,7 @@ if [[ -f "$c_test_file" ]]; then
     echo "$c_test_file"
     mkdir -p "$tmp_dir"
     cd "$tmp_dir"
-    test_exit_code < "../../../$c_test_file"
+    test_exit_code 0 < "../../../$c_test_file"
     cd "../../.."
 elif [[ -f "$sh_test_file" ]]; then
     source tests/helpers.sh