Re: [PATCH v2 2/8] Add support for emulation of CRC32 instructions

[Philippe Mathieu-Daudé]

Hi Aleksandar,

On 18/10/24 10:19, Aleksandar Rakic wrote:

Add emulation of MIPS' CRC32 (Cyclic Redundancy Check) instructions.
Reuse zlib crc32() and Linux crc32c().

Cherry-picked 4cc974938aee1588f852590509004e340c072940
from https://github.com/MIPS/gnutools-qemu

Signed-off-by: Yongbok Kim <yongbok....@mips.com>
Signed-off-by: Aleksandar Markovic <amarko...@wavecomp.com>
Signed-off-by: Aleksandar Rakic <aleksandar.ra...@htecgroup.com>
---
  target/mips/helper.h        |  2 ++
  target/mips/meson.build     |  1 +
  target/mips/tcg/op_helper.c | 26 ++++++++++++++++++++++++++
  target/mips/tcg/translate.c | 37 +++++++++++++++++++++++++++++++++++++
  target/mips/tcg/translate.h |  1 +
  5 files changed, 67 insertions(+)

diff --git a/target/mips/tcg/translate.c b/target/mips/tcg/translate.c
index 333469b268..256fa0893e 100644
--- a/target/mips/tcg/translate.c
+++ b/target/mips/tcg/translate.c
@@ -430,6 +430,7 @@ enum {
      OPC_LWE            = 0x2F | OPC_SPECIAL3,

/* R6 */

+    OPC_CRC32          = 0x0F | OPC_SPECIAL3,
      R6_OPC_PREF        = 0x35 | OPC_SPECIAL3,
      R6_OPC_CACHE       = 0x25 | OPC_SPECIAL3,
      R6_OPC_LL          = 0x36 | OPC_SPECIAL3,

@@ -13705,6 +13730,17 @@ static void decode_opc_special3_r6(CPUMIPSState *env, 
DisasContext *ctx)

op1 = MASK_SPECIAL3(ctx->opcode);

      switch (op1) {
+    case OPC_CRC32:
+        if (unlikely(!ctx->crcp) ||
+            unlikely((extract32(ctx->opcode, 6, 2) == 3) &&
+                     (!(ctx->hflags & MIPS_HFLAG_64))) ||
+            unlikely((extract32(ctx->opcode, 8, 3) >= 2))) {
+            gen_reserved_instruction(ctx);
+        }
+        gen_crc32(ctx, rt, rs, rt,
+                  extract32(ctx->opcode, 6, 2),
+                  extract32(ctx->opcode, 8, 3));
+        break;

New opcode must be implemented in decodetree format, please
add these in target/mips/tcg/rel6* files (the change should be
trivial and should only involve modifying few lines -- see for
example commit 675bf34a6fe and around).

Thanks,

Phil.