aef24d8f7d
Some arm64 instructions accept ZR as its destination register, such as MOVD, AND, ADD etc. although it doesn't seem to make much sense, but we should make sure the encoding is correct. However there exists some encoding mistakes in the current assembler, they are: 1, 'MOVD $1, ZR' is incorrectly encoded as 'MOVD $1, ZR' + '0x00000000'. 2, 'AND $1, R2, ZR' is incorrectly encoded as 'MOVD $1, R27' + 'AND R27, R2, ZR' + '0x00000000'. 3, 'AND $1, ZR' is incorrectly encoded as 'AND $1, ZR, RSP'. Obviously the first two encoding errors can cause SIGILL, and the third one will rewrite RSP. At the same time, I found some weird encodings but they don't cause errors. 4, 'MOVD $0x0001000100010001, ZR' is encoded as 'MOVW $1, ZR' + 'MOVKW $(1<<16), ZR'. 5, 'AND $0x0001000100010001, R2, ZR' is encoded as 'MOVD $1, R27' + 'MOVK $(1<<16), R27' + 'MOVK $(1<<32), R27'. Some of these issues also apply to 32-bit versions of these instructions. These problems are not very complicated, and are basically caused by the improper adaptation of the class of the constant to the entry in the optab. But the relationship between these constant classes is a bit complicated, so I don't know how to deal with issue 4 and 5, because they won't cause errors, so this CL didn't deal with them. This CL fixed the first three issues. Issue 1: before: 'MOVD $1, ZR' => 'MOVD $1, ZR' + '0x00000000'. after: 'MOVD $1, ZR' => 'MOVD $1, ZR'. Issue 2: before: 'AND $1, R2, ZR' => 'MOVD $1, R27' + 'AND R27, R2, ZR' + '0x00000000'. after: 'AND $1, R2, ZR' => 'ORR $1, ZR, R27' + 'AND R27, R2, ZR'. Issue 3: before: 'AND $1, ZR' => 'AND $1, ZR, RSP'. after: 'AND $1, ZR' => 'ORR $1, ZR, R27' + 'AND R27, ZR, ZR'. Change-Id: I3c889079229f847b863ad56c88966be12d947202 Reviewed-on: https://go-review.googlesource.com/c/go/+/329750 Reviewed-by: eric fang <eric.fang@arm.com> Reviewed-by: Cherry Mui <cherryyz@google.com> Trust: eric fang <eric.fang@arm.com> Run-TryBot: eric fang <eric.fang@arm.com> TryBot-Result: Go Bot <gobot@golang.org>
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