From bf2569a9a880ea6fbd908042fecccab8a96a2640 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Wed, 22 Sep 2021 13:06:30 +0300
Subject: [PATCH] all: support `mut volatile x := 123` declarations (#11940)

---
 doc/docs.md                                |  1 +
 vlib/v/ast/ast.v                           |  2 ++
 vlib/v/fmt/fmt.v                           |  3 +++
 vlib/v/gen/c/cgen.v                        |  3 +++
 vlib/v/gen/c/testdata/volatile.c.must_have |  2 ++
 vlib/v/gen/c/testdata/volatile.out         |  2 ++
 vlib/v/gen/c/testdata/volatile.vv          |  4 ++++
 vlib/v/parser/assign.v                     |  5 +++++
 vlib/v/parser/expr.v                       |  2 +-
 vlib/v/parser/parser.v                     |  8 +++++++-
 vlib/v/tests/struct_test.v                 |  5 +----
 vlib/v/tests/volatile_vars_test.v          | 14 ++++++++++++++
 vlib/v/token/token.v                       |  2 ++
 13 files changed, 47 insertions(+), 6 deletions(-)
 create mode 100644 vlib/v/gen/c/testdata/volatile.c.must_have
 create mode 100644 vlib/v/gen/c/testdata/volatile.out
 create mode 100644 vlib/v/gen/c/testdata/volatile.vv
 create mode 100644 vlib/v/tests/volatile_vars_test.v

diff --git a/doc/docs.md b/doc/docs.md
index 74c295b9cf..744a99aa75 100644
--- a/doc/docs.md
+++ b/doc/docs.md
@@ -5530,6 +5530,7 @@ type
 typeof
 union
 unsafe
+volatile
 __offsetof
 ```
 See also [V Types](#v-types).
diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index aee1efe656..8be7718a50 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -703,6 +703,7 @@ pub mut:
 	typ         Type
 	is_mut      bool
 	is_static   bool
+	is_volatile bool
 	is_optional bool
 	share       ShareType
 }
@@ -996,6 +997,7 @@ pub mut:
 	left_types    []Type
 	right_types   []Type
 	is_static     bool // for translated code only
+	is_volatile   bool // for disabling variable access optimisations (needed for hardware drivers)
 	is_simple     bool // `x+=2` in `for x:=1; ; x+=2`
 	has_cross_var bool
 }
diff --git a/vlib/v/fmt/fmt.v b/vlib/v/fmt/fmt.v
index c282fc42f5..e11197d5e3 100644
--- a/vlib/v/fmt/fmt.v
+++ b/vlib/v/fmt/fmt.v
@@ -1719,6 +1719,9 @@ pub fn (mut f Fmt) ident(node ast.Ident) {
 		if var_info.is_static {
 			f.write('static ')
 		}
+		if var_info.is_volatile {
+			f.write('volatile ')
+		}
 	}
 	f.write_language_prefix(node.language)
 	if node.name == 'it' && f.it_name != '' && !f.inside_lambda { // allow `it` in lambdas
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 293971b69f..9f1ff6e164 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -2374,6 +2374,9 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 	if assign_stmt.is_static {
 		g.write('static ')
 	}
+	if assign_stmt.is_volatile {
+		g.write('volatile ')
+	}
 	mut return_type := ast.void_type
 	is_decl := assign_stmt.op == .decl_assign
 	g.assign_op = assign_stmt.op
diff --git a/vlib/v/gen/c/testdata/volatile.c.must_have b/vlib/v/gen/c/testdata/volatile.c.must_have
new file mode 100644
index 0000000000..a88594038a
--- /dev/null
+++ b/vlib/v/gen/c/testdata/volatile.c.must_have
@@ -0,0 +1,2 @@
+volatile int *zzz = HEAP(int, (123));
+volatile int* pzzz = &(*(zzz));
diff --git a/vlib/v/gen/c/testdata/volatile.out b/vlib/v/gen/c/testdata/volatile.out
new file mode 100644
index 0000000000..f3da5b535e
--- /dev/null
+++ b/vlib/v/gen/c/testdata/volatile.out
@@ -0,0 +1,2 @@
+123
+&123
diff --git a/vlib/v/gen/c/testdata/volatile.vv b/vlib/v/gen/c/testdata/volatile.vv
new file mode 100644
index 0000000000..2c95812473
--- /dev/null
+++ b/vlib/v/gen/c/testdata/volatile.vv
@@ -0,0 +1,4 @@
+mut volatile zzz := 123
+mut volatile pzzz := &zzz
+println(zzz)
+println(&int(voidptr(pzzz)))
diff --git a/vlib/v/parser/assign.v b/vlib/v/parser/assign.v
index 76c074ae05..a477969714 100644
--- a/vlib/v/parser/assign.v
+++ b/vlib/v/parser/assign.v
@@ -156,6 +156,7 @@ fn (mut p Parser) partial_assign_stmt(left []ast.Expr, left_comments []ast.Comme
 		}
 	}
 	mut is_static := false
+	mut is_volatile := false
 	for i, lx in left {
 		match mut lx {
 			ast.Ident {
@@ -174,6 +175,9 @@ fn (mut p Parser) partial_assign_stmt(left []ast.Expr, left_comments []ast.Comme
 							}
 							is_static = true
 						}
+						if iv.is_volatile {
+							is_volatile = true
+						}
 					}
 					r0 := right[0]
 					mut v := ast.Var{
@@ -232,5 +236,6 @@ fn (mut p Parser) partial_assign_stmt(left []ast.Expr, left_comments []ast.Comme
 		has_cross_var: has_cross_var
 		is_simple: p.inside_for && p.tok.kind == .lcbr
 		is_static: is_static
+		is_volatile: is_volatile
 	}
 }
diff --git a/vlib/v/parser/expr.v b/vlib/v/parser/expr.v
index e96fdaf4c3..14a0b390cb 100644
--- a/vlib/v/parser/expr.v
+++ b/vlib/v/parser/expr.v
@@ -32,7 +32,7 @@ pub fn (mut p Parser) check_expr(precedence int) ?ast.Expr {
 	}
 	// Prefix
 	match p.tok.kind {
-		.key_mut, .key_shared, .key_atomic, .key_static {
+		.key_mut, .key_shared, .key_atomic, .key_static, .key_volatile {
 			ident := p.parse_ident(ast.Language.v)
 			node = ident
 			if p.inside_defer {
diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index 34c471f853..9193e87380 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -865,7 +865,7 @@ fn (mut p Parser) asm_stmt(is_top_level bool) ast.AsmStmt {
 	mut arch := pref.arch_from_string(p.tok.lit) or { pref.Arch._auto }
 	mut is_volatile := false
 	mut is_goto := false
-	if p.tok.lit == 'volatile' && p.tok.kind == .name {
+	if p.tok.kind == .key_volatile {
 		arch = pref.arch_from_string(p.peek_tok.lit) or { pref.Arch._auto }
 		is_volatile = true
 		p.next()
@@ -1820,6 +1820,10 @@ pub fn (mut p Parser) parse_ident(language ast.Language) ast.Ident {
 	if is_static {
 		p.next()
 	}
+	is_volatile := p.tok.kind == .key_volatile
+	if is_volatile {
+		p.next()
+	}
 	if p.tok.kind != .name {
 		p.error('unexpected token `$p.tok.lit`')
 		return ast.Ident{
@@ -1838,6 +1842,7 @@ pub fn (mut p Parser) parse_ident(language ast.Language) ast.Ident {
 			info: ast.IdentVar{
 				is_mut: false
 				is_static: false
+				is_volatile: false
 			}
 			scope: p.scope
 		}
@@ -1861,6 +1866,7 @@ pub fn (mut p Parser) parse_ident(language ast.Language) ast.Ident {
 		info: ast.IdentVar{
 			is_mut: is_mut
 			is_static: is_static
+			is_volatile: is_volatile
 			share: ast.sharetype_from_flags(is_shared, is_atomic)
 		}
 		scope: p.scope
diff --git a/vlib/v/tests/struct_test.v b/vlib/v/tests/struct_test.v
index 3349c9fe6e..1e89c25483 100644
--- a/vlib/v/tests/struct_test.v
+++ b/vlib/v/tests/struct_test.v
@@ -60,7 +60,6 @@ struct ReservedKeywords {
 	typedef  int
 	unsigned int
 	void     int
-	volatile int
 	while    int
 }
 
@@ -120,18 +119,16 @@ fn test_at() {
 
 fn test_reserved_keywords() {
 	// Make sure we can initialize them correctly using full syntax.
-	rk_holder := ReservedKeywords{0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3}
+	rk_holder := ReservedKeywords{0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3}
 	// Test a few as it'll take too long to test all. If it's initialized
 	// correctly, other fields are also probably valid.
 	assert rk_holder.unix == 5
 	assert rk_holder.while == 3
 	rk_holder2 := ReservedKeywords{
 		inline: 9
-		volatile: 11
 	}
 	// Make sure partial initialization works too.
 	assert rk_holder2.inline == 9
-	assert rk_holder2.volatile == 11
 	assert rk_holder2.while == 0 // Zero value as not specified.
 }
 
diff --git a/vlib/v/tests/volatile_vars_test.v b/vlib/v/tests/volatile_vars_test.v
new file mode 100644
index 0000000000..42c62a1225
--- /dev/null
+++ b/vlib/v/tests/volatile_vars_test.v
@@ -0,0 +1,14 @@
+fn test_volatile_var() {
+	mut volatile zzz := 123
+	assert zzz == 123
+}
+
+fn test_volatile_pointer() {
+	x := 123
+	y := 456
+	mut volatile p := unsafe { &x }
+	println(p)
+	p = unsafe { &y }
+	println(p)
+	assert unsafe { *p == y }
+}
diff --git a/vlib/v/token/token.v b/vlib/v/token/token.v
index eb7ebe2799..1f787ee107 100644
--- a/vlib/v/token/token.v
+++ b/vlib/v/token/token.v
@@ -126,6 +126,7 @@ pub enum Kind {
 	key_union
 	key_pub
 	key_static
+	key_volatile
 	key_unsafe
 	keyword_end
 	_end_
@@ -303,6 +304,7 @@ fn build_token_str() []string {
 	s[Kind.key_global] = '__global'
 	s[Kind.key_union] = 'union'
 	s[Kind.key_static] = 'static'
+	s[Kind.key_volatile] = 'volatile'
 	s[Kind.key_as] = 'as'
 	s[Kind.key_defer] = 'defer'
 	s[Kind.key_match] = 'match'