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Re: [PATCH] target/hppa: Allow, but diagnose, LDCW aligned only mod 4
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [PATCH] target/hppa: Allow, but diagnose, LDCW aligned only mod 4 |
Date: |
Fri, 17 Jan 2020 19:20:32 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 |
On 1/17/20 6:30 PM, Richard Henderson wrote:
On 1/17/20 6:13 AM, Philippe Mathieu-Daudé wrote:
- MemOp mop = MO_TEUL | MO_ALIGN_16 | a->size;
+ MemOp mop = MO_TE | MO_ALIGN | a->size;
Hmmm you changed MO_TEUL -> MO_TE, so from MO_32 to MO_8.
Per your description, shouldn't this be MO_TEUL | MO_ALIGN_4?
The "UL" part is also being added by a->size. This code was written this way
in preparation for the 64-bit ldc, and the bug was not noticable because we
don't have that yet.
Ah I missed the a->size.
So on 32-bit the hw trap doesn't trap on unaligned 16, but traps on
unaligned 4.
On 64-bit we don't know yet, but IIUC we expect to not trap on unaligned 8.
Looking at target/hppa/insns.decode:
&ldst t b x disp sp m scale size
@ldstx ...... b:5 x:5 sp:2 scale:1 ....... m:1 t:5 &ldst disp=0
@ldim5 ...... b:5 ..... sp:2 ......... t:5 \
&ldst disp=%im5_16 x=0 scale=0 m=%ma_to_m
ldc 000011 ..... ..... .. . 1 -- 0111 ...... @ldim5
size=2
ldc 000011 ..... ..... .. . 0 -- 0111 ...... @ldstx
size=2
We have a->size = 2 = MO_32 = MO_UL.
So do you plan to add LDCD from PA2.0 using size=3, OK.
From "exec/memop.h":
* MO_ALIGN supposes the alignment size is the size of a memory access.
*
* There are three options:
* - unaligned access permitted (MO_UNALN).
* - an alignment to the size of an access (MO_ALIGN);
Ah so with LDCW we already access a word, so MO_ALIGN -> MO_ALIGN_4.
With LDLD we'll have MO_ALIGN -> MO_ALIGN_8.
Now "MemOp mop = MO_TE | MO_ALIGN | a->size;" makes sense!
The power of your decodetree script amazed me again :)
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
- [PATCH] target/hppa: Allow, but diagnose, LDCW aligned only mod 4, Richard Henderson, 2020/01/16
- Re: [PATCH] target/hppa: Allow, but diagnose, LDCW aligned only mod 4, Helge Deller, 2020/01/17
- Re: [PATCH] target/hppa: Allow, but diagnose, LDCW aligned only mod 4, Philippe Mathieu-Daudé, 2020/01/17
- Re: [PATCH] target/hppa: Allow, but diagnose, LDCW aligned only mod 4, Helge Deller, 2020/01/17
- Re: [PATCH] target/hppa: Allow, but diagnose, LDCW aligned only mod 4, Richard Henderson, 2020/01/17
- Re: [PATCH] target/hppa: Allow, but diagnose, LDCW aligned only mod 4, John David Anglin, 2020/01/17
- Re: [PATCH] target/hppa: Allow, but diagnose, LDCW aligned only mod 4, Richard Henderson, 2020/01/17
- Re: [PATCH] target/hppa: Allow, but diagnose, LDCW aligned only mod 4,
Philippe Mathieu-Daudé <=
Re: [PATCH] target/hppa: Allow, but diagnose, LDCW aligned only mod 4, Philippe Mathieu-Daudé, 2020/01/17