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Re: [Qemu-devel] [RFC v1 05/23] riscv: Add the tcg-target header file
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [RFC v1 05/23] riscv: Add the tcg-target header file |
Date: |
Fri, 16 Nov 2018 08:57:06 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 |
On 11/15/18 11:34 PM, Alistair Francis wrote:
> +#define TCG_TARGET_HAS_add2_i32 0
> +#define TCG_TARGET_HAS_sub2_i32 0
You're not allowed to not implement this for riscv-32,
along with brcond2 and setcond2.
> +#define TCG_TARGET_HAS_movcond_i32 0
The architecture manual suggests that implementations recognize short
branch-over and convert internally to predication. Do any do that?
Even if they don't, you might implement it that way anyway, as the code size
savings are large vs the inline fallback (6 insns). But you can definitely put
that off for a later patch.
> +#define TCG_TARGET_HAS_ext16u_i32 1
Really? I thought this required two insns... Or do you expand to shifts while
the default is x & 0xffff, which would take 3 insns? I guess I'll find out as
I keep reading. ;-)
r~
- [Qemu-devel] [RFC v1 01/23] elf.h: Add the RISCV ELF magic numbers, (continued)
- [Qemu-devel] [RFC v1 01/23] elf.h: Add the RISCV ELF magic numbers, Alistair Francis, 2018/11/15
- [Qemu-devel] [RFC v1 02/23] linux-user: Add host dependency for RISC-V 32-bit, Alistair Francis, 2018/11/15
- [Qemu-devel] [RFC v1 03/23] linux-user: Add host dependency for RISC-V 64-bit, Alistair Francis, 2018/11/15
- [Qemu-devel] [RFC v1 04/23] exec: Add RISC-V GCC poison macro, Alistair Francis, 2018/11/15
- [Qemu-devel] [RFC v1 05/23] riscv: Add the tcg-target header file, Alistair Francis, 2018/11/15
- [Qemu-devel] [RFC v1 06/23] riscv: Add the tcg target registers, Alistair Francis, 2018/11/15
- [Qemu-devel] [RFC v1 07/23] riscv: tcg-target: Regiser the JIT, Alistair Francis, 2018/11/15
- [Qemu-devel] [RFC v1 08/23] riscv: tcg-target: Add support for the constraints, Alistair Francis, 2018/11/15
- [Qemu-devel] [RFC v1 09/23] riscv: tcg-target: Add the immediate encoders, Alistair Francis, 2018/11/15
- [Qemu-devel] [RFC v1 11/23] riscv: tcg-target: Add the relocation functions, Alistair Francis, 2018/11/15