Changes `xorpd(r,r)` and `xorq(r, r)` to `xorps(r,r)` and `xorl(r, r)`, which saves one (REX prefix) byte and still clears the register. (At least if the register is in the first 8, otherwise a REX byte is needed just to name the register. Still better to let the compiler worry about that than hardwiring a 64-bit `q` or `pd` operation.)
Changes `andq` to `AndImmediate` which recognizes that a 32-bit or smaller immediate only needs an `andl` (again potentially saving a REX prefix).
Simplifies the code for clamping an Uint8Clamped value to have fewer branches. (If we know the value is not in the 0..255 range, two instructions can convert all negative values to zero, and all positive values to a value with the lower 8 bit set: `(~v)>>63`.)
Simplifies the code for "is infinite" to use one less 64-bit immediate (by multiplying by 2 to shift out the sign, rather than masking it out using a 63-bit mask.)
Tested: No new behavior, only optimization. Covered by existing tests.
Change-Id: I94e66c2ff39f0a207649f657e4da1ed43e4e819e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/385741
Commit-Queue: Lasse Nielsen <lrn@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Lasse R.H. Nielsen
b99b43a657