target/sh4: mac.w: memory accesses are 16-bit words

Before this change, executing a code sequence such as:

           mova   tblm,r0
           mov    r0,r1
           mova   tbln,r0
           clrs
           clrmac
           mac.w  @r0+,@r1+
           mac.w  @r0+,@r1+

           .align 4
  tblm:    .word  0x1234
           .word  0x5678
  tbln:    .word  0x9abc
           .word  0xdefg

Does not result in correct behavior:

Expected behavior:
  first macw : macl = 0x1234 * 0x9abc + 0x0
               mach = 0x0

  second macw: macl = 0x5678 * 0xdefg + 0xb00a630
               mach = 0x0

Observed behavior (qemu-sh4eb, prior to this commit):

  first macw : macl = 0x5678 * 0xdefg + 0x0
               mach = 0x0

  second macw: (unaligned longword memory access, SIGBUS)

Various SH-4 ISA manuals also confirm that `mac.w` is a 16-bit word memory
access, not a 32-bit longword memory access.

Signed-off-by: Zack Buhman <zack@buhman.org>
Reviewed-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20240402093756.27466-1-zack@buhman.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
(cherry picked from commit b0f2f29)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

target/sh4/translate.c

@@ -817,10 +817,10 @@ static void _decode_opc(DisasContext * ctx)
             TCGv arg0, arg1;
             arg0 = tcg_temp_new();
             tcg_gen_qemu_ld_i32(arg0, REG(B7_4), ctx->memidx,
-                                MO_TESL | MO_ALIGN);
+                                MO_TESW | MO_ALIGN);
             arg1 = tcg_temp_new();
             tcg_gen_qemu_ld_i32(arg1, REG(B11_8), ctx->memidx,
-                                MO_TESL | MO_ALIGN);
+                                MO_TESW | MO_ALIGN);
             gen_helper_macw(tcg_env, arg0, arg1);
             tcg_gen_addi_i32(REG(B11_8), REG(B11_8), 2);
             tcg_gen_addi_i32(REG(B7_4), REG(B7_4), 2);