Port 66964c51

Original Commit Message:

    Extract codegen into macro-assembler functions for reuse in Liftoff.

    Some minor tweaks in I32x4TruncSatF64x2SZero and I32x4TruncSatF64x2UZero
    to check dst and src overlap and move to scratch/dst accordingly. In
    TurboFan we can set these restrictions in the instruction-selector, but
    not in Liftoff. This doesn't make TurboFan codegen any worse, since
    those restrictions are still in place.

R=zhin@chromium.org, joransiu@ca.ibm.com, junyan@redhat.com, midawson@redhat.com
BUG=
LOG=N

Change-Id: Iae59472a5e77c1becc5ff880081f2c0c8c149630
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2690828Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#72676}