gasm-sdk/asm/riscv_encode_test.go

// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: BSD-3-Clause

package asm

import (
	"testing"

	"sourcedock.dev/petrbalvin/gasm-devkit/ast"
	"sourcedock.dev/petrbalvin/gasm-devkit/parser"
)

// firstTextRISCV parses assembly source and returns the first TEXT function body.
func firstTextRISCV(t *testing.T, src string) *ast.Text {
	t.Helper()
	f, errs := parser.Parse("f_riscv64.s", src)
	if len(errs) > 0 {
		t.Fatalf("parse: %v", errs)
	}
	for _, d := range f.Decls {
		if fn, ok := d.(*ast.Text); ok {
			return fn
		}
	}
	t.Fatal("no TEXT found")
	return nil
}

// assembleRISCVHelper assembles one TEXT function and returns its code bytes.
func assembleRISCVHelper(t *testing.T, fn *ast.Text) []byte {
	t.Helper()
	code, _, err := assembleRISCV(fn)
	if err != nil {
		t.Fatalf("assemble: %v", err)
	}
	return code
}

func TestRISCV_add(t *testing.T) {
	// func add(a, b int64) int64
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·add(SB), NOSPLIT, $0-24
	MOV a+0(FP), X10
	MOV b+8(FP), X11
	ADD X11, X10, X10
	MOV X10, ret+16(FP)
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// should be 12 bytes with RVC: C.LDSP + C.LDSP + ADD + C.SDSP + C.JR
	_ = code
	if len(code) == 0 {
		t.Error("empty output")
	}
}

func TestRISCV_arithmetic(t *testing.T) {
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·arith(SB), NOSPLIT, $0
	ADD X10, X11, X12
	SUB X12, X13, X14
	MUL X14, X15, X16
	DIV X16, X17, X18
	REM X18, X19, X20
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// 5 R-type instructions + RET compressed = 5*4 + 2 = 22
	if len(code) != 22 {
		t.Errorf("expected 22 bytes, got %d", len(code))
	}
}

func TestRISCV_loadStore(t *testing.T) {
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·mem(SB), NOSPLIT, $0
	LD (X10), X11
	SD X11, (X12)
	LW (X13), X14
	SW X14, (X15)
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// 4 loads/stores (4B each) + C.JR RET (2B) = 18
	if len(code) != 18 {
		t.Errorf("expected 18 bytes, got %d", len(code))
	}
}

func TestRISCV_immediate(t *testing.T) {
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·imm(SB), NOSPLIT, $0
	ADDI X10, $42, X11
	ANDI X11, $0xFF, X12
	ORI X12, $1, X13
	XORI X13, $0, X14
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// 4 I-type + C.JR = 4*4 + 2 = 18
	if len(code) != 18 {
		t.Errorf("expected 18 bytes, got %d", len(code))
	}
}

func TestRISCV_branches(t *testing.T) {
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·br(SB), NOSPLIT, $0
	ADDI X10, $1, X10
loop:
	BEQ X10, X11, done
	ADDI X10, $1, X10
	JMP loop
done:
	RET
`)
	code := assembleRISCVHelper(t, fn)
	_ = code
	if len(code) == 0 {
		t.Error("empty output")
	}
}

func TestRISCV_MOV_imm_small(t *testing.T) {
	// MOV $42, rd → ADDI (fits in 12 bits). Not RVC-compressed (treated as MOV, not ADDI).
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·small(SB), NOSPLIT, $0
	MOV $42, X10
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// ADDI (4B) + C.JR (2B) = 6
	if len(code) != 6 {
		t.Errorf("expected 6 bytes, got %d", len(code))
	}
}

func TestRISCV_MOV_imm_large(t *testing.T) {
	// MOV $0x12345, rd → LUI + ADDIW (8 bytes total)
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·large(SB), NOSPLIT, $0
	MOV $0x12345, X10
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// LUI (4B) + ADDIW (4B) + C.JR (2B) = 10
	if len(code) != 10 {
		t.Errorf("expected 10 bytes, got %d", len(code))
	}
}

func TestRISCV_MOV_reg(t *testing.T) {
	// MOV rs, rd → ADDI $0, rs, rd, compresses to C.MV
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·reg(SB), NOSPLIT, $0
	MOV X10, X11
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// C.MV (2B) + C.JR (2B) = 4
	if len(code) != 4 {
		t.Errorf("expected 4 bytes, got %d (% x)", len(code), code)
	}
}

func TestRISCV_MOV_frame(t *testing.T) {
	// MOV name+off(FP), rd → load with frame mapping
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·frame(SB), NOSPLIT, $0-8
	MOV a+0(FP), X10
	MOV X10, ret+0(FP)
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// C.LDSP (2B) + C.SDSP (2B) + C.JR (2B) = 6
	if len(code) != 6 {
		t.Errorf("expected 6 bytes, got %d", len(code))
	}
}

func TestRISCV_RVC_loadStore(t *testing.T) {
	// Verify that loads/stores from SP (X2) are compressed.
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·rvcstore(SB), NOSPLIT, $0
	LD 0(X2), X10
	SD X10, 8(X2)
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// C.LDSP (2B) + C.SDSP (2B) + C.JR (2B) = 6
	if len(code) != 6 {
		t.Errorf("expected 6 bytes, got %d (% x)", len(code), code)
	}
}

func TestRISCV_atomics(t *testing.T) {
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·amo(SB), NOSPLIT, $0
	AMOADDD X10, (X11), X12
	LRD (X13), X14
	SCD X15, (X16), X17
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// 3 AMO instructions (4B each) + C.JR (2B) = 14
	if len(code) != 14 {
		t.Errorf("expected 14 bytes, got %d", len(code))
	}
}

func TestRISCV_fpArith(t *testing.T) {
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·fpadd(SB), NOSPLIT, $0
	FADDD F10, F11, F12
	FSUBD F12, F13, F14
	FMULD F14, F15, F16
	FDIVD F16, F17, F18
	FSQRTD F18, F19
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// 5 FP instructions (4B each) + C.JR (2B) = 22
	if len(code) != 22 {
		t.Errorf("expected 22 bytes, got %d (%d)", len(code), len(code))
	}
}

func TestRISCV_csr(t *testing.T) {
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·csrtest(SB), NOSPLIT, $0
	CSRRS $0x300, X0, X10
	CSRRW $0x305, X10, X11
	CSRRSI $0x304, $5, X12
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// 3 CSR instructions (4B each) + C.JR (2B) = 14
	if len(code) != 14 {
		t.Errorf("expected 14 bytes, got %d", len(code))
	}
}

func TestRISCV_fma(t *testing.T) {
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·fmatest(SB), NOSPLIT, $0
	FMADDD F10, F11, F12, F13
	FMSUBD F13, F14, F15, F16
	FNMSUBD F16, F17, F18, F19
	FNMADDD F19, F10, F11, F12
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// 4 FMA instructions (4B each) + C.JR (2B) = 18
	if len(code) != 18 {
		t.Errorf("expected 18 bytes, got %d", len(code))
	}
}

func TestRISCV_conversions(t *testing.T) {
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·cvt(SB), NOSPLIT, $0
	FCVTDL X10, F10
	FCVTLD F10, X11
	FMVXD F10, X12
	FMVDX X12, F11
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// 4 conversion instructions (4B each) + C.JR (2B) = 18
	if len(code) != 18 {
		t.Errorf("expected 18 bytes, got %d", len(code))
	}
}

func TestRISCV_fpCmp(t *testing.T) {
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·cmp(SB), NOSPLIT, $0
	FEQD F10, F11, X10
	FLTD F12, F13, X11
	FLED F14, F15, X12
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// 3 FP compare (4B each) + C.JR (2B) = 14
	if len(code) != 14 {
		t.Errorf("expected 14 bytes, got %d", len(code))
	}
}

func TestRISCV_forwardBranch(t *testing.T) {
	// Forward label reference — must not fail.
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·fwd(SB), NOSPLIT, $0
	ADDI X10, $1, X10
	BEQ X10, X11, done
	ADDI X10, $1, X10
done:
	RET
`)
	code := assembleRISCVHelper(t, fn)
	_ = code
	if len(code) == 0 {
		t.Error("empty output")
	}
}

func TestRISCV_RVC_ADDI(t *testing.T) {
	// ADDI where rd=rs1 and small imm → C.ADDI
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·caddi(SB), NOSPLIT, $0
	ADDI X10, $5, X10
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// C.ADDI (2B) + C.JR (2B) = 4
	if len(code) != 4 {
		t.Errorf("expected 4 bytes, got %d", len(code))
	}
}

func TestRISCV_RVC_LI(t *testing.T) {
	// ADDI X0, $imm, rd → C.LI
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·cli(SB), NOSPLIT, $0
	ADDI X0, $7, X10
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// C.LI (2B) + C.JR (2B) = 4
	if len(code) != 4 {
		t.Errorf("expected 4 bytes, got %d", len(code))
	}
}

func TestRISCV_RVC_LUI(t *testing.T) {
	// LUI rd, small nonzero imm → C.LUI
	fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·clui(SB), NOSPLIT, $0
	LUI X10, $1
	RET
`)
	code := assembleRISCVHelper(t, fn)
	// C.LUI (2B) + C.JR (2B) = 4
	if len(code) != 4 {
		t.Errorf("expected 4 bytes, got %d", len(code))
	}
}

func TestRISCV_AssembleFile(t *testing.T) {
	src := `#include "textflag.h"

TEXT ·add(SB), NOSPLIT, $0-24
	MOV a+0(FP), X10
	RET

TEXT ·sub(SB), NOSPLIT, $0
	SUB X10, X11, X12
	RET
`
	f, errs := parser.Parse("t_riscv64.s", src)
	if len(errs) > 0 {
		t.Fatalf("parse: %v", errs)
	}
	img, err := AssembleFileRISCV(f)
	if err != nil {
		t.Fatalf("AssembleFileRISCV: %v", err)
	}
	if len(img.Funcs) != 2 {
		t.Fatalf("expected 2 functions, got %d", len(img.Funcs))
	}
	// func add: C.LDSP(2) + C.JR(2) = 4
	if img.Funcs[0].Size != 4 {
		t.Errorf("add: expected 4 bytes, got %d", img.Funcs[0].Size)
	}
	// func sub: SUB(4) + C.JR(2) = 6
	if img.Funcs[1].Size != 6 {
		t.Errorf("sub: expected 6 bytes, got %d", img.Funcs[1].Size)
	}
}

func TestRISCV_encodings(t *testing.T) {
	// Smoke test that all known RISC-V mnemonics encode successfully.
	tests := []struct {
		name, src string
		wantBytes int
	}{
		{"ADD", "ADD X10, X11, X12\nRET\n", 6},
		{"SUBW", "SUBW X10, X11, X12\nRET\n", 6},
		{"MUL", "MUL X10, X11, X12\nRET\n", 6},
		{"DIVW", "DIVW X10, X11, X12\nRET\n", 6},
		{"REMUW", "REMUW X10, X11, X12\nRET\n", 6},
		{"ADDIW", "ADDIW X10, $5, X11\nRET\n", 6},
		{"SLLI", "SLLI X10, $3, X11\nRET\n", 6}, // ADDI+SLLI? No, SLLI uses I-type
		{"SRLI", "SRLI X10, $2, X11\nRET\n", 6},
		{"SRAI", "SRAI X10, $1, X11\nRET\n", 6},
		{"LB", "LB (X10), X11\nRET\n", 6},
		{"LBU", "LBU (X10), X11\nRET\n", 6},
		{"LH", "LH (X10), X11\nRET\n", 6},
		{"LHU", "LHU (X10), X11\nRET\n", 6},
		{"LWU", "LWU (X10), X11\nRET\n", 6},
		{"SB", "SB X10, (X11)\nRET\n", 6},
		{"SH", "SH X10, (X11)\nRET\n", 6},
		{"SW", "SW X10, (X11)\nRET\n", 6},
		{"LUI", "LUI X10, $0x12345\nRET\n", 6},
		{"AUIPC", "AUIPC X10, $0\nRET\n", 6},
		{"FLW", "FLW (X10), F10\nRET\n", 6},
		{"FSW", "FSW F10, (X11)\nRET\n", 6},
		{"FADDS", "FADDS F10, F11, F12\nRET\n", 6},
		{"FMINS", "FMINS F10, F11, F12\nRET\n", 6},
		{"FMAXD", "FMAXD F10, F11, F12\nRET\n", 6},
		{"FCVTSD", "FCVTSD F10, F11\nRET\n", 6},
		{"FCVTDS", "FCVTDS F10, F11\nRET\n", 6},
		{"FMVXW", "FMVXW F10, X10\nRET\n", 6},
		{"FMADD_S", "FMADDS F10, F11, F12, F13\nRET\n", 6},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			fn := firstTextRISCV(t, `#include "textflag.h"
TEXT ·`+tt.name+`(SB), NOSPLIT, $0
	`+tt.src)
			code := assembleRISCVHelper(t, fn)
			if len(code) != tt.wantBytes {
				t.Errorf("expected %d bytes, got %d", tt.wantBytes, len(code))
			}
		})
	}
}