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I've checked `_bfd_mips_elf_get_synthetic_symtab' and that function doesn't attempt to match against the move part of the PLT entry, so I don't believe any updates are required there. I've added specific disassembly tests for the move macro, (move.d, micromips32-move.d). Issues on comments addressed. Updated tests pass check-gas. Thanks, Simon -----Original Message----- From: Maciej W. Rozycki [mailto:macro@linux-mips.org] Sent: 30 July 2015 23:11 To: Simon Dardis Cc: binutils@sourceware.org; Matthew Fortune; rdsandiford@googlemail.com; Moore, Catherine Subject: Re: FW: [PATCH,MIPS] Change the mapping for the 'move' instruction On Thu, 30 Jul 2015, Simon Dardis wrote: > This patch updates the MIPS move instruction alias so that it is 'or' > instead of [d]addu for microMIPS, MIPS32 and MIPS64. The reasoning > behind this change was brought up in an earlier RFC from Matthew > Fortune: > > http://sourceware.org/ml/binutils/2015-03/msg00001.html > > "This issue was identified during performance analysis of a recent > 64-bit design by Imagination and the use of addu for 32-bit moves can > inhibit some pipeline forwarding optimisations as the addu has to sign > extend in 64-bit implementations. I suspect there are ways to deal > with this in hardware but regardless it seems sensible to use the same > instruction for move in 32-bit and 64-bit code." > > This patch preserves existing disassembler behavior, e.g assembling > 'daddu t7, ra, zero' and then disassembling it gives back 'move t7,ra'. > > Tested with no new regression with check-ld, check-gas, check-binutils. The changes to PLT entries produced may require corresponding updates to `_bfd_mips_elf_get_synthetic_symtab' -- have you checked that they are indeed unneeded? I see no mention of that anywhere. Maciej
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MIPS-move-as-or.patch
Description: MIPS-move-as-or.patch
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