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cmd/compile/internal/ssa: optimize ARM SSA rules with indexed MOVB/MOVH #21492

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benshi001 opened this issue Aug 17, 2017 · 1 comment

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@benshi001
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commented Aug 17, 2017

There are indexed MOVW used for ARM.

{name: "MOVWloadidx", argLength: 3, reg: gp2load, asm: "MOVW"},                   // load from arg0 + arg1. arg2=mem
{name: "MOVWloadshiftLL", argLength: 3, reg: gp2load, asm: "MOVW", aux: "Int32"}, // load from arg0 + arg1<<auxInt. arg2=mem
{name: "MOVWloadshiftRL", argLength: 3, reg: gp2load, asm: "MOVW", aux: "Int32"}, // load from arg0 + arg1>>auxInt, unsigned shift. arg2=mem
{name: "MOVWloadshiftRA", argLength: 3, reg: gp2load, asm: "MOVW", aux: "Int32"}, // load from arg0 + arg1>>auxInt, signed shift. arg2=mem
{name: "MOVWstoreidx", argLength: 4, reg: gp2store, asm: "MOVW"},                   // store arg2 to arg0 + arg1. arg3=mem
{name: "MOVWstoreshiftLL", argLength: 4, reg: gp2store, asm: "MOVW", aux: "Int32"}, // store arg2 to arg0 + arg1<<auxInt. arg3=mem
{name: "MOVWstoreshiftRL", argLength: 4, reg: gp2store, asm: "MOVW", aux: "Int32"}, // store arg2 to arg0 + arg1>>auxInt, unsigned shift. arg3=mem
{name: "MOVWstoreshiftRA", argLength: 4, reg: gp2store, asm: "MOVW", aux: "Int32"}, // store arg2 to arg0 + arg1>>auxInt, signed shift. arg3=mem

But corresponding ones for MOVB/MOVH are absent. Adding and using them can save bytes.

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commented Aug 28, 2017

Change https://golang.org/cl/58450 mentions this issue: cmd/compile: optimize ARM with more efficient MOVB/MOVBU/MOVH/MOVHU

@golang golang deleted a comment from daiweisong Aug 28, 2017
@gopherbot gopherbot closed this in a2f22a6 Aug 28, 2017
@golang golang locked and limited conversation to collaborators Aug 28, 2018
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