By calling ZSTD_CCtx_setPledgedSrcSize, we can let zstd know
how large a chunk is going to be before which start compressing
it, which lets zstd avoid allocating more memory than needed
for various internal buffers. This greatly reduces the RAM usage
when using a high compression level with a small chunk size,
and doesn't have much of an effect in other circumstances.
A side effect of calling ZSTD_CCtx_setPledgedSrcSize is that
zstd by default will write the uncompressed size into the
compressed data stream as metadata. In order to save space,
and since the decompressed size can be figured out through
the structure of the RVZ format anyway, we disable writing
the uncompressed size by setting ZSTD_c_contentSizeFlag to 0.
Unlike Super Paper Mario, this game doesn't crash as soon as you
try to start it, but rather if you try to skip a certain cutscene.
Thanks to JMC for letting me know about this.
For the non-packed variant of this instruction, a MOVSD instruction was
generated to copy only the lower 64 bits of XMM1 to the destination
register. This was done in order to keep the destination register's
upper half intact.
However, when register c and the destination register are the same,
there is no need for this copy. Because the registers match and due to
the way the mask is generated, BLENDVPD will end up taking the upper
half from the destination register, as intended.
Additionally, the MOVAPS to copy Rc into XMM1 can also be skipped.
Before:
66 0F 57 C0 xorpd xmm0,xmm0
F2 41 0F C2 C6 06 cmpnlesd xmm0,xmm14
41 0F 28 CE movaps xmm1,xmm14
66 41 0F 38 15 CA blendvpd xmm1,xmm10,xmm0
F2 44 0F 10 F1 movsd xmm14,xmm1
After:
66 0F 57 C0 xorpd xmm0,xmm0
F2 41 0F C2 C6 06 cmpnlesd xmm0,xmm14
66 45 0F 38 15 F2 blendvpd xmm14,xmm10,xmm0
For the non-packed variant of this instruction, a MOVSD instruction was
generated to copy only the lower 64 bits of XMM1 to the destination
register. This was done in order to keep the destination register's
upper half intact.
However, when register c and the destination register are the same,
there is no need for this copy. Because the registers match and due to
the way the mask is generated, VBLENDVPD will end up taking the upper
half from the destination register, as intended.
Before:
66 0F 57 C0 xorpd xmm0,xmm0
F2 41 0F C2 C6 06 cmpnlesd xmm0,xmm14
C4 C3 09 4B CA 00 vblendvpd xmm1,xmm14,xmm10,xmm0
F2 44 0F 10 F1 movsd xmm14,xmm1
After:
66 0F 57 C0 xorpd xmm0,xmm0
F2 41 0F C2 C6 06 cmpnlesd xmm0,xmm14
C4 43 09 4B F2 00 vblendvpd xmm14,xmm14,xmm10,xmm0
