From: Richard Henderson <richard.henderson@linaro.org>
To: Peter Maydell <peter.maydell@linaro.org>,
qemu-arm@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [PATCH 07/10] target/arm: Implement v8.1M low-overhead-loop instructions
Date: Tue, 13 Oct 2020 15:31:29 -0700 [thread overview]
Message-ID: <ad79b081-211a-a591-4de1-7fb0096d331f@linaro.org> (raw)
In-Reply-To: <20201012153746.9996-8-peter.maydell@linaro.org>
On 10/12/20 8:37 AM, Peter Maydell wrote:
> + nextlabel = gen_new_label();
> + tcg_gen_brcondi_i32(TCG_COND_NE, cpu_R[a->rn], 0, nextlabel);
> + gen_jmp(s, read_pc(s) + a->imm);
> +
> + gen_set_label(nextlabel);
> + tmp = load_reg(s, a->rn);
> + store_reg(s, 14, tmp);
> + gen_jmp(s, s->base.pc_next);
> + return true;
Oh, fwiw, with the tcg optimization patches just posted, this branch is better
inverted. That way the load of rn can be reused on the non-taken branch path.
Maybe sometime I'll try to propagate the data to the taken path, but that
automatically requires extra memory allocation, so it'll be difficult to do
that without a tcg slowdown.
r~
next prev parent reply other threads:[~2020-10-13 22:33 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-12 15:37 [PATCH 00/10] target/arm: Various v8.1M minor features Peter Maydell
2020-10-12 15:37 ` [PATCH 01/10] decodetree: Fix codegen for non-overlapping group inside overlapping group Peter Maydell
2020-10-13 16:02 ` Richard Henderson
2020-10-12 15:37 ` [PATCH 02/10] target/arm: Implement v8.1M NOCP handling Peter Maydell
2020-10-12 15:37 ` [PATCH 03/10] target/arm: Implement v8.1M conditional-select insns Peter Maydell
2020-10-13 16:37 ` Richard Henderson
2020-10-12 15:37 ` [PATCH 04/10] target/arm: Make the t32 insn[25:23]=111 group non-overlapping Peter Maydell
2020-10-13 16:40 ` Richard Henderson
2020-10-12 15:37 ` [PATCH 05/10] target/arm: Don't allow BLX imm for M-profile Peter Maydell
2020-10-13 16:41 ` Richard Henderson
2020-10-12 15:37 ` [PATCH 06/10] target/arm: Implement v8.1M branch-future insns (as NOPs) Peter Maydell
2020-10-13 16:58 ` Richard Henderson
2020-10-12 15:37 ` [PATCH 07/10] target/arm: Implement v8.1M low-overhead-loop instructions Peter Maydell
2020-10-12 19:56 ` Peter Maydell
2020-10-13 17:10 ` Richard Henderson
2020-10-13 17:12 ` Peter Maydell
2020-10-13 17:30 ` Richard Henderson
2020-10-13 20:24 ` Peter Maydell
2020-10-13 22:31 ` Richard Henderson [this message]
2020-10-12 15:37 ` [PATCH 08/10] target/arm: Fix has_vfp/has_neon ID reg squashing for M-profile Peter Maydell
2020-10-13 19:07 ` Richard Henderson
2020-10-12 15:37 ` [PATCH 09/10] target/arm: Implement FPSCR.LTPSIZE for M-profile LOB extension Peter Maydell
2020-10-13 20:06 ` Richard Henderson
2020-10-13 20:38 ` Peter Maydell
2020-10-13 21:01 ` Richard Henderson
2020-10-12 15:37 ` [PATCH 10/10] target/arm: Fix writing to FPSCR.FZ16 on M-profile Peter Maydell
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