[Webkit-unassigned] [Bug 231159] New: [JSC][ARMv7] Improve instruction selection in MacroAssembler

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=231159

            Bug ID: 231159
           Summary: [JSC][ARMv7] Improve instruction selection in
                    MacroAssembler
           Product: WebKit
           Version: WebKit Nightly Build
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: JavaScriptCore
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: glore at igalia.com

I have spotted some improvement opportunities in MacroAssemblerARMv7 for better instruction selection for some macros. What shows up most often in the disassembly ('ip' is 'r12'):

mvn ip, #8
and r0, r0, ip

This is an 8-byte sequence which is equivalent to the following 2-byte instruction:

bic r0, #8


similarly:

mvn ip, #7
add r0, r0, ip

should be:

sub r0, r0, #8

A review of the disassembly would likely yield more examples of similar sequences where an immediate can be encoded cheaper using an alternative instruction.

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.webkit.org/pipermail/webkit-unassigned/attachments/20211004/cd04e4b5/attachment.htm>