feat(riscv64): GOROOT instruction shapes, DATA order and offset expressions

Assisted-by: GLM 5.3 Flash

parser/parser.go

@@ -438,25 +438,56 @@ func parseAddress(g []token.Token) ast.Address {
 	// Optional leading displacement before a '(' base group.  A sign pushes
 	// the parenthesis one token further out: -4(DX) has it at i+2.
 	if isSignedNumber(g, i) {
-		paren := i + 1
-		if g[i].Kind == token.Minus || g[i].Kind == token.Plus {
-			paren = i + 2
+		j := i
+		neg := false
+		if g[j].Kind == token.Minus {
+			neg = true
+			j++
+		} else if g[j].Kind == token.Plus {
+			j++
 		}
-		if paren < len(g) && g[paren].Kind == token.LParen {
-			neg := false
-			if g[i].Kind == token.Minus {
-				neg = true
-				i++
-			} else if g[i].Kind == token.Plus {
-				i++
+		if j < len(g) && g[j].Kind == token.Number {
+			v := parseInt(g[j].Text)
+			j++
+			// A term may carry a *number factor: 0*8(base).
+			for j+1 < len(g) && g[j].Kind == token.Star && g[j+1].Kind == token.Number {
+				v *= parseInt(g[j+1].Text)
+				j += 2
 			}
-			if i < len(g) && g[i].Kind == token.Number {
-				addr.Offset = parseInt(g[i].Text)
-				addr.HasOff = true
-				if neg {
-					addr.Offset = -addr.Offset
+			if neg {
+				v = -v
+			}
+			// Further +/- terms, each with its optional factor:
+			// 3*8+8(base), 8-4*2(base).
+			for {
+				termNeg := false
+				if j < len(g) && g[j].Kind == token.Minus {
+					termNeg = true
+				} else if j < len(g) && g[j].Kind == token.Plus {
+				} else {
+					break
 				}
-				i++
+				if j+1 < len(g) && g[j+1].Kind == token.Number {
+					tv := parseInt(g[j+1].Text)
+					j += 2
+					for j+1 < len(g) && g[j].Kind == token.Star && g[j+1].Kind == token.Number {
+						tv *= parseInt(g[j+1].Text)
+						j += 2
+					}
+					if termNeg {
+						tv = -tv
+					}
+					v += tv
+					continue
+				}
+				break
+			}
+			// Commit only when the expression is followed by the base
+			// group; a bare number stays untouched for the caller.
+			if j < len(g) && g[j].Kind == token.LParen {
+				addr.Offset = v
+				addr.HasOff = true
+				i = j
 			}
 		}
 	}