From: mengqinggang <mengqinggang@loongson.cn>
To: binutils@sourceware.org, i.swmail@xen0n.name
Cc: xuchenghua@loongson.cn, liuzhensong@loongson.cn,
Xi Ruoyao <xry111@xry111.site>
Subject: This series patches result in some gas/ld test errors. There are some,files need to be regenerated.
Date: Tue, 13 Dec 2022 16:13:50 +0800 [thread overview]
Message-ID: <aa758969-04d0-4f0c-f70a-1fa3826a7e5e@loongson.cn> (raw)
This patch result in some gas/ld test errors. There are some
files need to be regenerated.
Add a flag in the pinfo field for being able to mark certain specialized
matchers as disassembler-only, so some degree of isolation between
assembler-side and disassembler-side can be achieved.
This isolation is necessary, firstly because some pseudo-instructions
cannot be fully described in the opcode table, like `li.[wd]`, so the
corresponding opcode entry cannot have meaningful match/mask values.
Secondly, some of these pseudo-instructions can be realized in more than
one plausible ways; e.g. `li.w rd, <something between 0 and 0x7ff>` can
be realized on LA64 with any of `addi.w`, `addi.d` or `ori`. If we tie
disassembly of such aliases with the corresponding GAS support, only one
canonical form among the above would be recognized as `li.w`, and it
would mildly impact the readability of disassembly output.
People wanting the exact disassembly can always set `-M no-aliases` to
get the original behavior back.
In addition, in certain cases, information is irreversibly lost after
assembling, so perfect round-trip would not be possible in such cases.
For example, `li.w` and `li.d` of immediates within int32_t range
produce the same code; in this patch, `addi.d rd, $zero, imm` is treated
as `li.d`, while `addi.w` and `ori` immediate loads are shown as `li.w`,
due to the expressible value range well within 32 bits.
reply other threads:[~2022-12-13 8:13 UTC|newest]
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