asm: add segment addressing and fix [10] (#12068)

vlib/v/ast/ast.v

@@ -1260,6 +1260,7 @@ pub:
 	mode  AddressingMode
 	pos   token.Position
 pub mut:
+	segment      string // fs:
 	displacement AsmArg // 8, 16 or 32 bit literal value
 	base         AsmArg // gpr
 	index        AsmArg // gpr

vlib/v/gen/c/cgen.v

@@ -2488,6 +2488,9 @@ fn (mut g Gen) asm_arg(arg ast.AsmArg, stmt ast.AsmStmt) {
 			g.write('%$arg.name')
 		}
 		ast.AsmAddressing {
+			if arg.segment != '' {
+				g.write('%%$arg.segment:')
+			}
 			base := arg.base
 			index := arg.index
 			displacement := arg.displacement
@@ -2500,7 +2503,6 @@ fn (mut g Gen) asm_arg(arg ast.AsmArg, stmt ast.AsmStmt) {
 				}
 				.displacement {
 					g.asm_arg(displacement, stmt)
-					g.write('()')
 				}
 				.base_plus_displacement {
 					g.asm_arg(displacement, stmt)

vlib/v/parser/parser.v

@@ -942,6 +942,12 @@ fn (mut p Parser) asm_stmt(is_top_level bool) ast.AsmStmt {
 				if p.prev_tok.position().line_nr < p.tok.position().line_nr {
 					break
 				}
+				mut segment := ''
+				if p.tok.kind == .name && p.peek_tok.kind == .colon {
+					segment = p.tok.lit
+					p.next()
+					p.next()
+				}
 				match p.tok.kind {
 					.name {
 						args << p.reg_or_alias()
@@ -985,7 +991,9 @@ fn (mut p Parser) asm_stmt(is_top_level bool) ast.AsmStmt {
 						break
 					}
 					.lsbr {
-						args << p.asm_addressing()
+						mut addressing := p.asm_addressing()
+						addressing.segment = segment
+						args << addressing
 					}
 					.rcbr {
 						break