fix(asm): encode RISC-V CALL sym(SB) as JAL

Assisted-by: DeepSeek V4 Pro

asm/riscv_encode_test.go

@@ -4,6 +4,7 @@
 package asm
 
 import (
+	"bytes"
 	"testing"
 
 	"sourcedock.dev/petrbalvin/gasm-devkit/ast"
@@ -720,19 +721,43 @@ TEXT ·badfp(SB), NOSPLIT, $0
 }
 
 func TestRISCV_CALL(t *testing.T) {
-	// CALL target → AUIPC + JALR (8 bytes).
+	// CALL sym(SB) → JAL X1, sym(SB) with a single R_RISCV_JAL relocation.
 	fn := firstTextRISCV(t, `#include "textflag.h"
 TEXT ·calltest(SB), NOSPLIT, $0
-	CALL sub
-done:
+	CALL ext(SB)
 	RET
+`)
+	code, _, relocs, _, _, err := assembleRISCV(fn)
+	if err != nil {
+		t.Fatalf("assemble: %v", err)
+	}
+	// prologue (8) + JAL (4) + epilogue+JALR (8) = 20
+	if len(code) != 20 {
+		t.Fatalf("expected 20 bytes with CALL sym(SB), got %d", len(code))
+	}
+	if len(relocs) != 1 {
+		t.Fatalf("relocs = %d, want 1", len(relocs))
+	}
+	r := relocs[0]
+	if r.Kind != RelRISCVJal || r.Name != "ext" || r.Off != 8 || r.After != 12 || r.Addend != 0 {
+		t.Errorf("reloc = {kind %v off %d after %d name %q addend %d}", r.Kind, r.Off, r.After, r.Name, r.Addend)
+	}
+	// The JAL instruction itself is JAL X1, 0 at function offset 8.
+	wantJAL := wordLE(riscvJType(1, 0))
+	if !bytes.Equal(code[8:12], wantJAL) {
+		t.Errorf("JAL = % x, want % x", code[8:12], wantJAL)
+	}
+}
+
+func TestRISCV_CALL_local_error(t *testing.T) {
+	fn := firstTextRISCV(t, `#include "textflag.h"
+TEXT ·calllocal(SB), NOSPLIT, $0
+	CALL sub
 sub:
 	RET
 `)
-	code := assembleRISCVHelper(t, fn)
-	// A zero-frame non-leaf function saves LR: prologue (8) + CALL (8) +
-	// two framed RETs (8 each) = 32.
-	if len(code) != 32 {
-		t.Errorf("expected 32 bytes with CALL, got %d", len(code))
+	_, _, _, _, _, err := assembleRISCV(fn)
+	if err == nil {
+		t.Error("expected error for CALL to local label, got nil")
 	}
 }