[Clang] Generalize interp__builtin_ia32_shuffle_generic to handle single op permute shuffles

[RKSimon]

Once #165085 has landed adding variable shuffle mask handling, we should be able to update interp__builtin_ia32_shuffle_generic to handle 2 arg (1 operand + 1 mask) cases as well and replace interp__builtin_x86_byteshift / interp__builtin_ia32_pshuf / interp__builtin_ia32_pshufb

Same for evalPshufBuiltin / evalPshufbBuiltin and BI__builtin_ia32_*_byteshift handling replaced with an updated evalShuffleGeneric

[llvmbot]

@llvm/issue-subscribers-backend-x86

Author: Simon Pilgrim (RKSimon)

Once #165085 has landed adding variable shuffle mask handling, we should be able to update interp__builtin_ia32_shuffle_generic to handle 2 arg (1 operand + 1 mask) cases as well and replace interp__builtin_x86_byteshift / interp__builtin_ia32_pshuf / interp__builtin_ia32_pshufb

Same for evalPshufBuiltin / evalPshufbBuiltin and BI__builtin_ia32_*_byteshift handling replaced with an updated evalShuffleGeneric

[llvmbot]

Hi!

This issue may be a good introductory issue for people new to working on LLVM. If you would like to work on this issue, your first steps are:

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3. Fix the issue locally.
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If you have any further questions about this issue, don't hesitate to ask via a comment in the thread below.

[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Simon Pilgrim (RKSimon)

Once #165085 has landed adding variable shuffle mask handling, we should be able to update interp__builtin_ia32_shuffle_generic to handle 2 arg (1 operand + 1 mask) cases as well and replace interp__builtin_x86_byteshift / interp__builtin_ia32_pshuf / interp__builtin_ia32_pshufb

Same for evalPshufBuiltin / evalPshufbBuiltin and BI__builtin_ia32_*_byteshift handling replaced with an updated evalShuffleGeneric

[TelGome]

Hi @RKSimon , I'd like to work on this issue.