commit b0f2f2976b4db05351117b0440b32bf0aac2c5c6
author Zack Buhman <zack@buhman.org> Tue Apr 02 17:37:49 2024 +0800
committer Richard Henderson <richard.henderson@linaro.org> Tue Apr 09 07:43:31 2024 -1000
tree 515c898292ad3c4d9076fb26a83dead6b7af6363
parent 26d937237f363297e5f70efcb001b15b1cb0fc2b

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>