From 871c29ea5d11253e9aab4488b010946c04af190c Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Mon, 20 Apr 2020 22:21:29 +0200
Subject: [PATCH] x64: fn calls; return;

---
 vlib/v/gen/x64/elf.v |  1 +
 vlib/v/gen/x64/gen.v | 41 +++++++++++++++++++++++------------------
 vlib/v/token/token.v |  4 +---
 3 files changed, 25 insertions(+), 21 deletions(-)

diff --git a/vlib/v/gen/x64/elf.v b/vlib/v/gen/x64/elf.v
index b9bdde1397..2098e9ef9f 100644
--- a/vlib/v/gen/x64/elf.v
+++ b/vlib/v/gen/x64/elf.v
@@ -66,6 +66,7 @@ pub fn (var g Gen) generate_elf_header() {
 	g.write64(0x1000) // p_align
 	// user code starts here at
 	// address: 00070 and a half
+	println('code_start_pos = $g.buf.len.hex()')
 	g.code_start_pos = g.buf.len
 	g.call(PLACEHOLDER) // call main function, it's not guaranteed to be the first, we don't know its address yet
 }
diff --git a/vlib/v/gen/x64/gen.v b/vlib/v/gen/x64/gen.v
index 53525ff788..02dc911d4f 100644
--- a/vlib/v/gen/x64/gen.v
+++ b/vlib/v/gen/x64/gen.v
@@ -194,11 +194,14 @@ fn (var g Gen) mov64(reg Register, val i64) {
 }
 
 fn (var g Gen) call(addr int) {
-	// rel := g.abs_to_rel_addr(addr)
-	// rel := 0xffffffff - int(abs(addr - g.buf.len))-1
-	println('call addr=$addr rel_addr=$addr pos=$g.buf.len')
+	// Need to calculate the difference between current position (position after the e8 call)
+	// and the function to call.
+	// +5 is to get the posistion "e8 xx xx xx xx"
+	// Not sure about the -1.
+	rel := 0xffffffff - (g.buf.len + 5 - addr - 1)
+	println('call addr=$addr.hex() rel_addr=$rel.hex() pos=$g.buf.len')
 	g.write8(0xe8)
-	g.write32(addr)
+	g.write32(rel)
 }
 
 fn (var g Gen) syscall() {
@@ -300,10 +303,14 @@ pub fn (g &Gen) writeln(s string) {
 }
 
 pub fn (var g Gen) call_fn(name string) {
+	println('call fn $name')
 	if !name.contains('__') {
-		return
+		// return
 	}
 	addr := g.fn_addr[name]
+	if addr == 0 {
+		verror('fn addr of `$name` = 0')
+	}
 	g.call(int(addr))
 	println('call $name $addr')
 }
@@ -313,8 +320,11 @@ fn (var g Gen) stmt(node ast.Stmt) {
 		ast.ConstDecl {}
 		ast.FnDecl {
 			is_main := it.name == 'main'
+			println('saving addr $it.name $g.buf.len.hex()')
 			if is_main {
 				g.save_main_fn_addr()
+			} else {
+				g.register_function_address(it.name)
 			}
 			for arg in it.args {
 			}
@@ -324,11 +334,14 @@ fn (var g Gen) stmt(node ast.Stmt) {
 			if is_main {
 				println('end of main: gen exit')
 				g.gen_exit()
-				// g.write32(0x88888888)
+				// return
 			}
-			// g.ret()
+			g.ret()
+		}
+		ast.Return {
+			g.gen_exit()
+			g.ret()
 		}
-		ast.Return {}
 		ast.AssignStmt {}
 		ast.ForStmt {}
 		ast.StructDecl {}
@@ -360,17 +373,9 @@ fn (var g Gen) expr(node ast.Expr) {
 			if it.name in ['println', 'print', 'eprintln', 'eprint'] {
 				expr := it.args[0].expr
 				g.gen_print_from_expr(expr, it.name in ['println', 'eprintln'])
+				return
 			}
-			/*
-			g.write('${it.name}(')
-			for i, expr in it.args {
-				g.expr(expr)
-				if i != it.args.len - 1 {
-					g.write(', ')
-				}
-			}
-			g.write(')')
-*/
+			g.call_fn(it.name)
 		}
 		ast.ArrayInit {}
 		ast.Ident {}
diff --git a/vlib/v/token/token.v b/vlib/v/token/token.v
index d49831a366..b348062361 100644
--- a/vlib/v/token/token.v
+++ b/vlib/v/token/token.v
@@ -98,7 +98,6 @@ pub enum Kind {
 	key_goto
 	key_if
 	key_import
-	key_import_const
 	key_in
 	key_interface
 	key_is
@@ -234,7 +233,6 @@ fn build_token_str() []string {
 	s[Kind.key_enum] = 'enum'
 	s[Kind.key_interface] = 'interface'
 	s[Kind.key_pub] = 'pub'
-	s[Kind.key_import_const] = 'import_const'
 	s[Kind.key_in] = 'in'
 	s[Kind.key_atomic] = 'atomic'
 	s[Kind.key_orelse] = 'or'
@@ -267,7 +265,7 @@ pub fn is_key(key string) bool {
 }
 
 pub fn is_decl(t Kind) bool {
-	return t in [.key_enum, .key_interface, .key_fn, .key_struct, .key_type, .key_const, .key_import_const, .key_pub, .eof]
+	return t in [.key_enum, .key_interface, .key_fn, .key_struct, .key_type, .key_const, .key_pub, .eof]
 }
 
 pub fn (t Kind) is_assign() bool {