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From: "Philippe Mathieu-Daudé" <philmd@linaro.org>
To: qemu-devel@nongnu.org
Cc: "Aurelien Jarno" <aurelien@aurel32.net>,
	"Aleksandar Rikalo" <aleksandar.rikalo@syrmia.com>,
	"Jiaxun Yang" <jiaxun.yang@flygoat.com>,
	"Philippe Mathieu-Daudé" <philmd@linaro.org>,
	"Richard Henderson" <richard.henderson@linaro.org>
Subject: [PATCH] target/mips: Simplify Loongson MULTU.G opcode
Date: Thu, 31 Aug 2023 22:11:39 +0200	[thread overview]
Message-ID: <20230831201140.85799-1-philmd@linaro.org> (raw)

Since MULTU opcodes don't record the most significant bits
of the infinite result, sign-extending the sources make no
difference in the result.

Once we remove the sign extension of source registers, MULT
and MULTU are identical (as are DMULT and DMULTU).

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 target/mips/tcg/translate.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/target/mips/tcg/translate.c b/target/mips/tcg/translate.c
index 9bb40f1849..e0a76b9432 100644
--- a/target/mips/tcg/translate.c
+++ b/target/mips/tcg/translate.c
@@ -3625,8 +3625,6 @@ static void gen_loongson_integer(DisasContext *ctx, uint32_t opc,
         break;
     case OPC_MULTU_G_2E:
     case OPC_MULTU_G_2F:
-        tcg_gen_ext32u_tl(t0, t0);
-        tcg_gen_ext32u_tl(t1, t1);
         tcg_gen_mul_tl(cpu_gpr[rd], t0, t1);
         tcg_gen_ext32s_tl(cpu_gpr[rd], cpu_gpr[rd]);
         break;
-- 
2.41.0



             reply	other threads:[~2023-08-31 20:12 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-31 20:11 Philippe Mathieu-Daudé [this message]
2023-08-31 23:26 ` [PATCH] target/mips: Simplify Loongson MULTU.G opcode Richard Henderson

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