[Webkit-unassigned] [Bug 210639] New: offlineasm is generating the wrong load/store for the "orh" instruction.

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=210639

            Bug ID: 210639
           Summary: offlineasm is generating the wrong load/store for the
                    "orh" instruction.
           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: mark.lam at apple.com

For example, on ARM64E, it was generating the following:

    "\tldr w17, [x1, #0]\n"                                  // JavaScriptCore/llint/LowLevelInterpreter64.asm:919
    "\torr w17, w17, #64\n"                                  // JavaScriptCore/llint/LowLevelInterpreter64.asm:919
    "\tstr w17, [x1, #0]\n"                                  // JavaScriptCore/llint/LowLevelInterpreter64.asm:919

i.e. a 32-bit load, followed by a 32-bit OR, followed by a 32-bit store.

Instead, it should be generating the following:

    "\tldrh w17, [x1, #0]\n"                                 // JavaScriptCore/llint/LowLevelInterpreter64.asm:919
    "\torr w17, w17, #64\n"                                  // JavaScriptCore/llint/LowLevelInterpreter64.asm:919
    "\tstrh w17, [x1, #0]\n"                                 // JavaScriptCore/llint/LowLevelInterpreter64.asm:919

i.e. a 16-bit load, followed by a 32-bit OR, followed by a 16-bit store.

This bug also affects ARM64, ARMv7, and MIPS (basically any backend that uses riscLowerMisplacedAddresses() from rise.rb).
It does not affect x86, x86_64, and C_LOOP (which was written based on x86).

<rdar://problem/21501876>

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