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Re: [Qemu-devel] [ARM] Problem in a NEON instruction
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [ARM] Problem in a NEON instruction |
Date: |
Tue, 14 Oct 2008 11:23:38 +0200 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Tue, Jun 10, 2008 at 12:32:17PM +0200, Laurent Desnogues wrote:
> The rshl instruction is faulty. Note I did not check the correctness
> of that instruction in general, I only made a change that looked logical.
>
>
> Laurent
> --- svn-ref/target-arm/neon_helper.c 2008-06-09 08:52:48.000000000 +0200
> +++ svn/target-arm/neon_helper.c 2008-06-10 12:27:38.000000000 +0200
> @@ -456,7 +456,7 @@
> if (tmp >= sizeof(src1) * 8) { \
> dest = 0; \
> } else if (tmp < -sizeof(src1) * 8) { \
> - dest >>= sizeof(src1) * 8 - 1; \
> + dest = src1 >> (sizeof(src1) * 8 - 1); \
> } else if (tmp == -sizeof(src1) * 8) { \
> dest = src1 >> (tmp - 1); \
> dest++; \
Your patch is indeed correct. It seems there is another mistake (at
least compared to the 64-bit version) in this instruction, please find
an updated patch below.
diff --git a/target-arm/neon_helper.c b/target-arm/neon_helper.c
index 4ee5658..35fbaf5 100644
--- a/target-arm/neon_helper.c
+++ b/target-arm/neon_helper.c
@@ -456,11 +456,11 @@ uint64_t HELPER(neon_shl_s64)(uint64_t valop, uint64_t
shiftop)
if (tmp >= sizeof(src1) * 8) { \
dest = 0; \
} else if (tmp < -sizeof(src1) * 8) { \
- dest >>= sizeof(src1) * 8 - 1; \
+ dest = src1 >> (sizeof(src1) * 8 - 1); \
} else if (tmp == -sizeof(src1) * 8) { \
dest = src1 >> (tmp - 1); \
dest++; \
- src2 >>= 1; \
+ dest >>= 1; \
} else if (tmp < 0) { \
dest = (src1 + (1 << (-1 - tmp))) >> -tmp; \
} else { \
--
.''`. Aurelien Jarno | GPG: 1024D/F1BCDB73
: :' : Debian developer | Electrical Engineer
`. `' address@hidden | address@hidden
`- people.debian.org/~aurel32 | www.aurel32.net
- Re: [Qemu-devel] [ARM] Problem in a NEON instruction,
Aurelien Jarno <=