Update change log and frontpage

Docs/ChangeLog-3x.md

@@ -9,19 +9,24 @@ clocked at 4.2 GHz, running `astcenc` using AVX2 and 6 threads.
 <!-- ---------------------------------------------------------------------- -->
 ## 3.7
 
-**Status:** In development
+**Status:** April 2022
 
-The 3.7 release is in development ...
+The 3.7 release contains another round of performance optimizations, including
+significant improvements to the command line front-end (faster PNG loader) and
+the arm64 build of the codec (faster NEON implementation).
 
 * **General:**
   * **Feature:** The command line tool PNG loader has been switched to use
     the Wuffs library, which is robust and significantly faster than the
     current stb_image implementation.
+  * **Feature:** Support for non-invariant builds returns. Opt-in to slightly
+    faster, but not bit-exact, builds by setting `-DNO_INVARIANCE=ON` for the
+    CMake configuration. This improves performance by around 2%.
   * **Optimization:** Changed SIMD `select()` so that it matches the default
     NEON behavior (bitwise select), rather than the default x86-64 behavior
     (lane select on MSB). Specialization `select_msb()` added for the one case
     we want to select on a sign-bit, where NEON needs a different
-    implementation. This provides a significant (20-25%) performance uplift on
+    implementation. This provides a significant (>25%) performance uplift on
     NEON implementations.
 
 ### Performance:
@@ -33,7 +38,7 @@ Key for charts:
 
 **Relative performance vs 3.5 release:**
 
-![Relative scores 3.6 vs 3.5](./ChangeLogImg/relative-3.5-to-3.6.png)
+![Relative scores 3.7 vs 3.6](./ChangeLogImg/relative-3.6-to-3.7.png)
 
 <!-- ---------------------------------------------------------------------- -->
 ## 3.6

README.md

@@ -58,7 +58,7 @@ from 0.89 bits/pixel up to 8 bits/pixel.
 Release build binaries for the `astcenc` stable releases are provided in the
 [GitHub Releases page][3].
 
-**Latest 3.x stable release:** 3.6
+**Latest 3.x stable release:** 3.7
 * Change log: [3.x series](./Docs/ChangeLog-3x.md)
 
 **Latest 2.x stable release:** 2.5

Test/astc_test_result_plot.py

@@ -260,7 +260,7 @@ def main():
         [
             # Relative scores
             ["thorough", "medium", "fast"],
-            ["ref-2.5-avx2", "ref-3.5-avx2"],
+            ["ref-2.5-avx2", "ref-3.7-avx2"],
             ["4x4", "6x6", "8x8"],
             True,
             "ref-1.7",
@@ -270,7 +270,7 @@ def main():
         ], [
             # Absolute scores
             ["thorough", "medium", "fast"],
-            ["ref-1.7", "ref-2.5-avx2", "ref-3.5-avx2"],
+            ["ref-1.7", "ref-2.5-avx2", "ref-3.7-avx2"],
             ["4x4", "6x6", "8x8"],
             False,
             None,
@@ -296,7 +296,7 @@ def main():
         [
             # Relative scores
             ["thorough", "medium", "fast"],
-            ["ref-3.6-avx2"],
+            ["ref-3.7-avx2"],
             ["4x4", "6x6", "8x8"],
             True,
             "ref-1.7",
@@ -309,7 +309,7 @@ def main():
         [
             # Relative scores
             ["thorough", "medium", "fast", "fastest"],
-            ["ref-3.6-avx2"],
+            ["ref-3.7-avx2"],
             ["4x4", "6x6", "8x8"],
             True,
             "ref-2.5-avx2",
@@ -322,27 +322,27 @@ def main():
         [
             # Relative scores
             ["thorough", "medium", "fast", "fastest"],
-            ["ref-3.6-avx2"],
+            ["ref-3.7-avx2"],
             ["4x4", "6x6", "8x8"],
             True,
-            "ref-3.5-avx2",
+            "ref-3.6-avx2",
             None,
             "relative-3.x-vs-3.x.png",
             (relXLimits, None),
         ], [
             # Relative ISAs of latest
             ["thorough", "medium", "fast", "fastest"],
-            ["ref-3.6-sse4.1", "ref-3.6-avx2"],
+            ["ref-3.7-sse4.1", "ref-3.7-avx2"],
             ["4x4", "6x6", "8x8"],
             True,
-            "ref-3.6-sse2",
+            "ref-3.7-sse2",
             None,
             "relative-3.x-isa.png",
             (None, None)
         ], [
             # Relative quality of latest
             ["medium", "fast", "fastest"],
-            ["ref-3.6-avx2"],
+            ["ref-3.7-avx2"],
             ["4x4", "6x6", "8x8"],
             True,
             None,