diff options
| author | Philippe Mathieu-Daudé | 2021-07-31 00:27:17 +0200 |
|---|---|---|
| committer | Philippe Mathieu-Daudé | 2021-08-25 12:49:09 +0200 |
| commit | c8b69a2a92bebed915af69bb685816e715956ecc (patch) | |
| tree | 1ae425771d6d658266edc7f79f9ecc95c0b6eba4 | |
| parent | Open 6.2 development tree (diff) | |
| download | qemu-c8b69a2a92bebed915af69bb685816e715956ecc.tar.gz qemu-c8b69a2a92bebed915af69bb685816e715956ecc.tar.xz qemu-c8b69a2a92bebed915af69bb685816e715956ecc.zip | |
target/mips: Remove JR opcode unused arguments
JR opcode (Jump Register) only takes 1 argument, $rs.
JALR (Jump And Link Register) takes 3: $rs, $rd and $hint.
Commit 6af0bf9c7c3 added their processing into decode_opc() as:
case 0x08 ... 0x09: /* Jumps */
gen_compute_branch(ctx, op1 | EXT_SPECIAL, rs, rd, sa);
having both opcodes handled in the same function: gen_compute_branch.
Per JR encoding, both $rd and $hint ('sa') are decoded as zero.
Later this code got extracted to decode_opc_special(),
commit 7a387fffce5 used definitions instead of magic values:
case OPC_JR ... OPC_JALR:
gen_compute_branch(ctx, op1, rs, rd, sa);
Finally commit 0aefa33318b moved OPC_JR out of decode_opc_special,
to a new 'decode_opc_special_legacy' function:
@@ -15851,6 +15851,9 @@ static void decode_opc_special_legacy(CPUMIPSState *env, DisasContext *ctx)
+ case OPC_JR:
+ gen_compute_branch(ctx, op1, 4, rs, rd, sa);
+ break;
@@ -15933,7 +15936,7 @@ static void decode_opc_special(CPUMIPSState *env, DisasContext *ctx)
- case OPC_JR ... OPC_JALR:
+ case OPC_JALR:
gen_compute_branch(ctx, op1, 4, rs, rd, sa);
break;
Since JR is now handled individually, it is pointless to decode
and pass it unused arguments. Replace them by simple zero value
to avoid confusion with this opcode.
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210730225507.2642827-1-f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
| -rw-r--r-- | target/mips/tcg/translate.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/target/mips/tcg/translate.c b/target/mips/tcg/translate.c index 5b03545f09..bf71724f3f 100644 --- a/target/mips/tcg/translate.c +++ b/target/mips/tcg/translate.c @@ -14203,7 +14203,7 @@ static void decode_opc_special_legacy(CPUMIPSState *env, DisasContext *ctx) break; #endif case OPC_JR: - gen_compute_branch(ctx, op1, 4, rs, rd, sa, 4); + gen_compute_branch(ctx, op1, 4, rs, 0, 0, 4); break; case OPC_SPIM: #ifdef MIPS_STRICT_STANDARD |