From 313855c232710378e1d3fad4fb4455991b9f45e9 Mon Sep 17 00:00:00 2001
From: herman ten brugge <hermantenbrugge@home.nl>
Date: Mon, 21 Mar 2022 11:40:43 +0100
Subject: [PATCH] Fix multi dimensional vla arrays on stack

There is no code generation in post_type for vla arrays. This code
generation has to be delayed until gen_function.

- post_type save code in type info.
- gen_function use this code to generate vla code.
- enable testcode for vla arrays.
---
 tcc.h           |  1 +
 tccgen.c        | 73 +++++++++++++++++++++++++++++++++++++++++++++++++
 tests/tcctest.c |  2 --
 3 files changed, 74 insertions(+), 2 deletions(-)

diff --git a/tcc.h b/tcc.h
index 04e68049..97248487 100644
--- a/tcc.h
+++ b/tcc.h
@@ -572,6 +572,7 @@ typedef struct Sym {
     };
     CType type; /* associated type */
     union {
+        int *vla_array_str; /* vla array code */
         struct Sym *next; /* next related symbol (for fields and anoms) */
         struct Sym *cleanupstate; /* in defined labels */
         int asm_label; /* associated asm label */
diff --git a/tccgen.c b/tccgen.c
index 0e0835f0..7d15dbea 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -5333,6 +5333,8 @@ static int post_type(CType *type, AttributeDef *ad, int storage, int td)
     Sym **plast, *s, *first;
     AttributeDef ad1;
     CType pt;
+    TokenString *vla_array_tok = NULL;
+    int *vla_array_str = NULL;
 
     if (tok == '(') {
         /* function type, or recursive declarator (return if so) */
@@ -5441,8 +5443,32 @@ static int post_type(CType *type, AttributeDef *ad, int storage, int td)
 		break;
 	    }
             if (tok != ']') {
+		int nest = 1;
+
+		/* Code generation is not done now but has to be done
+		   at start of function. Save code here for later use. */
 	        nocode_wanted = 1;
+		vla_array_tok = tok_str_alloc();
+		for (;;) {
+		    if (tok == ']') {
+			nest--;
+			if (nest == 0)
+			    break;
+		    }
+		    if (tok == '[')
+			nest++;
+		    tok_str_add_tok(vla_array_tok);
+		    next();
+		}
+		unget_tok(0);
+		tok_str_add(vla_array_tok, -1);
+		tok_str_add(vla_array_tok, 0);
+		vla_array_str = vla_array_tok->str;
+		begin_macro(vla_array_tok, 2);
+		next();
 	        gexpr();
+		end_macro();
+		next();
 		goto check;
             }
             break;
@@ -5504,6 +5530,12 @@ check:
         s = sym_push(SYM_FIELD, type, 0, n);
         type->t = (t1 ? VT_VLA : VT_ARRAY) | VT_PTR;
         type->ref = s;
+	if (vla_array_str) {
+	    if (t1 & VT_VLA)
+	        s->vla_array_str = vla_array_str;
+	    else
+	        tok_str_free_str(vla_array_str);
+	}
     }
     return 1;
 }
@@ -8592,6 +8624,46 @@ static void decl_initializer_alloc(CType *type, AttributeDef *ad, int r,
     nocode_wanted = saved_nocode_wanted;
 }
 
+/* generate vla code saved in post_type() */
+static void func_vla_arg_code(Sym *arg)
+{
+    int align;
+    TokenString *vla_array_tok = NULL;
+
+    if (arg->type.ref)
+        func_vla_arg_code(arg->type.ref);
+
+    if (arg->type.t & VT_VLA) {
+	loc -= type_size(&int_type, &align);
+	loc &= -align;
+	arg->type.ref->c = loc;
+
+	unget_tok(0);
+	vla_array_tok = tok_str_alloc();
+	vla_array_tok->str = arg->type.ref->vla_array_str;
+	begin_macro(vla_array_tok, 1);
+	next();
+	gexpr();
+	end_macro();
+	next();
+	vpush_type_size(&arg->type.ref->type, &align);
+	gen_op('*');
+	vset(&int_type, VT_LOCAL|VT_LVAL, arg->type.ref->c);
+	vswap();
+	vstore();
+	vpop();
+    }
+}
+
+static void func_vla_arg(Sym *sym)
+{
+    Sym *arg;
+
+    for (arg = sym->type.ref->next; arg; arg = arg->next)
+	if (arg->type.t & VT_VLA)
+	    func_vla_arg_code(arg);
+}
+
 /* parse a function defined by symbol 'sym' and generate its code in
    'cur_text_section' */
 static void gen_function(Sym *sym)
@@ -8626,6 +8698,7 @@ static void gen_function(Sym *sym)
     local_scope = 0;
     rsym = 0;
     clear_temp_local_var_list();
+    func_vla_arg(sym);
     block(0);
     gsym(rsym);
     nocode_wanted = 0;
diff --git a/tests/tcctest.c b/tests/tcctest.c
index 51c9c5bf..dfa5f4f0 100644
--- a/tests/tcctest.c
+++ b/tests/tcctest.c
@@ -3025,10 +3025,8 @@ void c99_vla_test_3(void)
     a[1][2][3] = 2;
     c99_vla_test_3a(a);
     c99_vla_test_3b(2, a);
-#if 0 // FIXME
     c99_vla_test_3c(3, a);
     c99_vla_test_3d(4, a);
-#endif
 }
 
 void c99_vla_test(void)