fix(parser): fold a signed parenthesised displacement expression

Assisted-by: GLM 5.3 Flash

asm/link.go

@@ -5,6 +5,7 @@ package asm
 
 import (
 	"fmt"
+	"math"
 	"sort"
 	"strconv"
 
@@ -299,6 +300,10 @@ func AssembleFileRISCV(f *ast.File) (*Image, error) {
 	if err != nil {
 		return nil, err
 	}
+	// The pooled $i64 constants the wide MOV immediate loads refer to join
+	// the declared data as read-only symbols, deduplicated across the file
+	// (the toolchain synthesises the same symbols into its rodata).
+	litSeen := map[string]bool{}
 
 	img := &Image{Symbols: map[string]int{}, SourcePath: f.Path}
 	for _, d := range f.Decls {
@@ -306,10 +311,23 @@ func AssembleFileRISCV(f *ast.File) (*Image, error) {
 		if !ok {
 			continue
 		}
-		code, labels, relocs, lines, spadj, err := assembleRISCV(t)
+		code, labels, relocs, lines, spadj, lits, err := assembleRISCV(t)
 		if err != nil {
 			return nil, fmt.Errorf("%s: %w", t.Name.Name, err)
 		}
+		for _, lit := range lits {
+			if litSeen[lit.Name] {
+				continue
+			}
+			litSeen[lit.Name] = true
+			dataSyms = append(dataSyms, dataSym{
+				name:   lit.Name,
+				buf:    lit.Data,
+				size:   len(lit.Data),
+				rodata: true,
+				dupok:  true,
+			})
+		}
 		fl := FuncLayout{
 			Name:   t.Name.Name,
 			Pkg:    t.Name.Pkg,
@@ -561,11 +579,6 @@ func collectData(f *ast.File) ([]dataSym, error) {
 			return nil, fmt.Errorf("DATA %q: missing value", dd.Name.Name)
 		}
 		w := dd.Width
-		switch w {
-		case 1, 2, 4, 8:
-		default:
-			return nil, fmt.Errorf("DATA %q: invalid width %d (want 1, 2, 4 or 8)", dd.Name.Name, w)
-		}
 		off := dd.Name.Offset
 		buf := syms[i].buf
 		if off < 0 || off+int64(w) > int64(len(buf)) {
@@ -587,9 +600,54 @@ func collectData(f *ast.File) ([]dataSym, error) {
 			})
 			continue
 		}
+		// A string or rune value ("DATA s+0(SB)/20, $"text"") writes its
+		// bytes into the field and leaves the rest zero, the toolchain's
+		// WriteString: the declared width must hold every byte, and any
+		// width is legal.
+		if s := dd.Value.Imm.Str; s != "" && !dd.Value.Imm.HasVal {
+			text, err := strconv.Unquote(s)
+			if err != nil {
+				return nil, fmt.Errorf("DATA %q: invalid string value %s", dd.Name.Name, s)
+			}
+			if len(text) > w {
+				return nil, fmt.Errorf("DATA %q: string of %d bytes does not fit width %d", dd.Name.Name, len(text), w)
+			}
+			copy(buf[off:], text)
+			continue
+		}
+		// A floating-point value stores its IEEE-754 bits: /4 the float32
+		// rounding of the parsed double, /8 the full 64 bits, the
+		// toolchain's WriteFloat32 and WriteFloat64.
+		if f := dd.Value.Imm.Float; f != "" && !dd.Value.Imm.HasVal {
+			num, err := strconv.ParseFloat(f, 64)
+			if err != nil {
+				return nil, fmt.Errorf("DATA %q: invalid floating-point value %q", dd.Name.Name, f)
+			}
+			if dd.Value.Imm.Neg {
+				num = -num
+			}
+			var v uint64
+			switch w {
+			case 4:
+				v = uint64(math.Float32bits(float32(num)))
+			case 8:
+				v = math.Float64bits(num)
+			default:
+				return nil, fmt.Errorf("DATA %q: invalid width %d for a float (want 4 or 8)", dd.Name.Name, w)
+			}
+			for j := range w {
+				buf[off+int64(j)] = byte(v >> (8 * j))
+			}
+			continue
+		}
 		if !dd.Value.Imm.HasVal {
 			return nil, fmt.Errorf("DATA %q: value must be an integer immediate or a symbol address", dd.Name.Name)
 		}
+		switch w {
+		case 1, 2, 4, 8:
+		default:
+			return nil, fmt.Errorf("DATA %q: invalid width %d (want 1, 2, 4 or 8)", dd.Name.Name, w)
+		}
 		v := dd.Value.Imm.Val
 		if dd.Value.Imm.Neg {
 			v = -v