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Re: [Qemu-riscv] [Qemu-devel] [RFC v1 05/23] riscv: Add the tcg-target h

From: Richard Henderson
Subject: Re: [Qemu-riscv] [Qemu-devel] [RFC v1 05/23] riscv: Add the tcg-target header file
Date: Fri, 16 Nov 2018 18:20:50 +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_extrl_i64_i32    0
> +#define TCG_TARGET_HAS_extrh_i64_i32    0

You need these two for rv64 to preserve the invariant that 32-bit values are
sign-extended in a 64-bit register.  Otherwise _i32 comparisons won't work

The first is yet another alias for exts32_i64; the second is an arithmetic
right shift of 32.  Their existence changes how code is emitted in tcg-op.c.


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