a little faster partitioning, runtime-checked avx fill

src/pixie/internal.nim

@@ -3,7 +3,8 @@ import chroma, common, system/memory, vmath
 const allowSimd* = not defined(pixieNoSimd) and not defined(tcc)
 
 when defined(amd64) and allowSimd:
-  import nimsimd/sse2
+  import nimsimd/runtimecheck, nimsimd/sse2, simd/avx
+  let cpuHasAvx* = checkInstructionSets({AVX})
 
 template currentExceptionAsPixieError*(): untyped =
   ## Gets the current exception and returns it as a PixieError with stack trace.
@@ -63,21 +64,29 @@ proc fillUnsafe*(
   ## Fills the image data with the color starting at index start and
   ## continuing for len indices.
   let rgbx = color.asRgbx()
+
+  # If we can use AVX, do so
+  when defined(amd64) and allowSimd:
+    if cpuHasAvx and len >= 64:
+      fillUnsafeAvx(data, rgbx, start, len)
+      return
+
   # Use memset when every byte has the same value
   if rgbx.r == rgbx.g and rgbx.r == rgbx.b and rgbx.r == rgbx.a:
     nimSetMem(data[start].addr, rgbx.r.cint, len * 4)
   else:
     var i = start
     when defined(amd64) and allowSimd:
       # Align to 16 bytes
-      while i < (start + len) and (cast[uint](data[i].addr) and 15) != 0:
+      var p = cast[uint](data[i].addr)
+      while i < (start + len) and (p and 15) != 0:
         data[i] = rgbx
         inc i
+        p += 4
       # When supported, SIMD fill until we run out of room
       let
         colorVec = mm_set1_epi32(cast[int32](rgbx))
         iterations = (start + len - i) div 8
-      var p = cast[uint](data[i].addr)
       for _ in 0 ..< iterations:
         mm_store_si128(cast[pointer](p), colorVec)
         mm_store_si128(cast[pointer](p + 16), colorVec)
@@ -93,8 +102,8 @@ proc fillUnsafe*(
           copyMem(data[i].addr, u64.addr, 8)
           i += 2
     # Fill whatever is left the slow way
-    for j in i ..< start + len:
-      data[j] = rgbx
+    for i in i ..< start + len:
+      data[i] = rgbx
 
 const straightAlphaTable = block:
   var table: array[256, array[256, uint8]]

src/pixie/paths.nim

@@ -1131,25 +1131,43 @@ proc partitionSegments(
     startY = top.uint32
     partitionHeight = height.uint32 div numPartitions
 
-  for (segment, winding) in segments:
-    var entry = initPartitionEntry(segment, winding)
-    if partitionHeight == 0:
-      result[0].entries.add(move entry)
-    else:
+  var entries = newSeq[PartitionEntry](segments.len)
+  for i, (segment, winding) in segments:
+    entries[i] = initPartitionEntry(segment, winding)
+
+  if numPartitions == 1:
+    result[0].entries = move entries
+  else:
+    iterator partitionRange(
+      segment: Segment,
+      numPartitions, startY, partitionHeight: uint32
+    ): uint32 =
       var
         atPartition = max(0, segment.at.y - startY.float32).uint32
         toPartition = max(0, segment.to.y - startY.float32).uint32
       atPartition = atPartition div partitionHeight
       toPartition = toPartition div partitionHeight
-      atPartition = min(atPartition, result.high.uint32)
-      toPartition = min(toPartition, result.high.uint32)
-      for i in atPartition .. toPartition:
-        result[i].entries.add(entry)
+      atPartition = min(atPartition, numPartitions - 1)
+      toPartition = min(toPartition, numPartitions - 1)
+      for partitionIndex in atPartition .. toPartition:
+        yield partitionIndex
 
-  # Set the bottom values for the partitions (y value where this partition ends)
+    var entryCounts = newSeq[int](numPartitions)
+    for (segment, _) in segments:
+      for partitionIndex in segment.partitionRange(numPartitions, startY, partitionHeight):
+        inc entryCounts[partitionIndex]
 
-  var partitionBottom = top + partitionHeight.int
+    for partitionIndex, entryCounts in entryCounts:
+      result[partitionIndex].entries.setLen(entryCounts)
+
+    var indexes = newSeq[int](numPartitions)
+    for i, (segment, winding) in segments:
+      for partitionIndex in segment.partitionRange(numPartitions, startY, partitionHeight):
+        result[partitionIndex].entries[indexes[partitionIndex]] = entries[i]
+        inc indexes[partitionIndex]
 
+  # Set the bottom values for the partitions (y value where this partition ends)
+  var partitionBottom = top + partitionHeight.int
   for partition in result.mitems:
     partition.bottom = partitionBottom
     partition.requiresAntiAliasing =
@@ -1313,7 +1331,7 @@ proc computeCoverage(
         if fillLen > 0:
           var i = fillStart
           when defined(amd64) and allowSimd:
-            let sampleCoverageVec = mm_set1_epi8(cast[int8](sampleCoverage))
+            let sampleCoverageVec = mm_set1_epi8(sampleCoverage)
             for _ in 0 ..< fillLen div 16:
               var coverageVec = mm_loadu_si128(coverages[i - startX].addr)
               coverageVec = mm_add_epi8(coverageVec, sampleCoverageVec)
@@ -1354,7 +1372,7 @@ proc fillCoverage(
           let
             coverageVec = mm_loadu_si128(coverages[x - startX].unsafeAddr)
             eqZero = mm_cmpeq_epi8(coverageVec, mm_setzero_si128())
-            eq255 = mm_cmpeq_epi8(coverageVec, mm_set1_epi8(cast[int8](255)))
+            eq255 = mm_cmpeq_epi8(coverageVec, mm_set1_epi8(255))
             allZeroes = mm_movemask_epi8(eqZero) == 0xffff
             all255 = mm_movemask_epi8(eq255) == 0xffff
           yield (coverageVec, allZeroes, all255)

src/pixie/simd/avx.nim

@@ -0,0 +1,35 @@
+import chroma, nimsimd/avx
+
+when defined(gcc) or defined(clang):
+  {.localPassc: "-mavx".}
+
+when defined(release):
+  {.push checks: off.}
+
+proc fillUnsafeAvx*(
+  data: var seq[ColorRGBX],
+  rgbx: ColorRGBX,
+  start, len: int
+) =
+  var
+    i = start
+    p = cast[uint](data[i].addr)
+  # Align to 32 bytes
+  while i < (start + len) and (p and 31) != 0:
+    data[i] = rgbx
+    inc i
+    p += 4
+  # When supported, SIMD fill until we run out of room
+  let
+    iterations = (start + len - i) div 8
+    colorVec = mm256_set1_epi32(cast[int32](rgbx))
+  for _ in 0 ..< iterations:
+    mm256_store_si256(cast[pointer](p), colorVec)
+    p += 32
+  i += iterations * 8
+  # Fill whatever is left the slow way
+  for i in i ..< start + len:
+    data[i] = rgbx
+
+when defined(release):
+  {.pop.}