diff mbox series

[PULL,10/35] target/sh4: mac.w: memory accesses are 16-bit words

Message ID 20240408174929.862917-11-richard.henderson@linaro.org
State Superseded
Headers show
Series [PULL,01/35] tcg/optimize: Do not attempt to constant fold neg_vec | expand

Commit Message

Richard Henderson April 8, 2024, 5:49 p.m. UTC 
From: Zack Buhman <zack@buhman.org>

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>
---
 target/sh4/translate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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Patch

diff --git a/target/sh4/translate.c b/target/sh4/translate.c
index a9b1bc7524..6643c14dde 100644
--- a/target/sh4/translate.c
+++ b/target/sh4/translate.c
@@ -816,10 +816,10 @@  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);