From b64ee0e190ccd360f5f7fb04783f010613c4c7c2 Mon Sep 17 00:00:00 2001
From: Gleb Mazovetskiy <glex.spb@gmail.com>
Date: Sun, 10 Sep 2023 06:46:31 +0100
Subject: [PATCH] Use `if constexpr` in clx/dun_render

---
 Source/engine/render/clx_render.cpp | 77 ++++++++++++++++++-----------
 Source/engine/render/dun_render.cpp | 24 ++++-----
 2 files changed, 59 insertions(+), 42 deletions(-)

diff --git a/Source/engine/render/clx_render.cpp b/Source/engine/render/clx_render.cpp
index 25b02ab6d..cff554ee5 100644
--- a/Source/engine/render/clx_render.cpp
+++ b/Source/engine/render/clx_render.cpp
@@ -212,45 +212,47 @@ void DoRenderBackwards(
 template <bool North, bool West, bool South, bool East>
 DVL_ALWAYS_INLINE DVL_ATTRIBUTE_HOT void RenderOutlineForPixel(uint8_t *dst, int dstPitch, uint8_t color)
 {
-	if (North)
+	if constexpr (North)
 		dst[-dstPitch] = color;
-	if (West)
+	if constexpr (West)
 		dst[-1] = color;
-	if (East)
+	if constexpr (East)
 		dst[1] = color;
-	if (South)
+	if constexpr (South)
 		dst[dstPitch] = color;
 }
 
 template <bool North, bool West, bool South, bool East, bool SkipColorIndexZero = true>
 DVL_ALWAYS_INLINE DVL_ATTRIBUTE_HOT void RenderOutlineForPixel(uint8_t *dst, int dstPitch, uint8_t srcColor, uint8_t color)
 {
-	if (SkipColorIndexZero && srcColor == 0)
-		return;
+	if constexpr (SkipColorIndexZero) {
+		if (srcColor == 0)
+			return;
+	}
 	RenderOutlineForPixel<North, West, South, East>(dst, dstPitch, color);
 }
 
 template <bool North, bool West, bool South, bool East>
 DVL_ALWAYS_INLINE DVL_ATTRIBUTE_HOT void RenderOutlineForPixels(uint8_t *dst, int dstPitch, int width, uint8_t color)
 {
-	if (North)
+	if constexpr (North)
 		std::memset(dst - dstPitch, color, width);
 
-	if (West && East)
+	if constexpr (West && East)
 		std::memset(dst - 1, color, width + 2);
-	else if (West)
+	else if constexpr (West)
 		std::memset(dst - 1, color, width);
-	else if (East)
+	else if constexpr (East)
 		std::memset(dst + 1, color, width);
 
-	if (South)
+	if constexpr (South)
 		std::memset(dst + dstPitch, color, width);
 }
 
 template <bool North, bool West, bool South, bool East, bool SkipColorIndexZero>
 DVL_ALWAYS_INLINE DVL_ATTRIBUTE_HOT void RenderOutlineForPixels(uint8_t *dst, int dstPitch, int width, const uint8_t *src, uint8_t color)
 {
-	if (SkipColorIndexZero) {
+	if constexpr (SkipColorIndexZero) {
 		while (width-- > 0)
 			RenderOutlineForPixel<North, West, South, East>(dst++, dstPitch, *src++, color);
 	} else {
@@ -264,7 +266,7 @@ void RenderClxOutlinePixelsCheckFirstColumn(
     const uint8_t *src, uint8_t width, uint8_t color)
 {
 	if (dstX == -1) {
-		if (Fill) {
+		if constexpr (Fill) {
 			RenderOutlineForPixel</*North=*/false, /*West=*/false, /*South=*/false, East>(
 			    dst++, dstPitch, color);
 		} else {
@@ -274,7 +276,7 @@ void RenderClxOutlinePixelsCheckFirstColumn(
 		--width;
 	}
 	if (width > 0) {
-		if (Fill) {
+		if constexpr (Fill) {
 			RenderOutlineForPixel<North, /*West=*/false, South, East>(dst++, dstPitch, color);
 		} else {
 			RenderOutlineForPixel<North, /*West=*/false, South, East, SkipColorIndexZero>(dst++, dstPitch, *src++, color);
@@ -282,7 +284,7 @@ void RenderClxOutlinePixelsCheckFirstColumn(
 		--width;
 	}
 	if (width > 0) {
-		if (Fill) {
+		if constexpr (Fill) {
 			RenderOutlineForPixels<North, West, South, East>(dst, dstPitch, width, color);
 		} else {
 			RenderOutlineForPixels<North, West, South, East, SkipColorIndexZero>(dst, dstPitch, width, src, color);
@@ -300,7 +302,7 @@ void RenderClxOutlinePixelsCheckLastColumn(
 	const int numSpecialPixels = (lastPixel ? 1 : 0) + (oobPixel ? 1 : 0);
 	if (width > numSpecialPixels) {
 		width -= numSpecialPixels;
-		if (Fill) {
+		if constexpr (Fill) {
 			RenderOutlineForPixels<North, West, South, East>(dst, dstPitch, width, color);
 		} else {
 			RenderOutlineForPixels<North, West, South, East, SkipColorIndexZero>(dst, dstPitch, width, src, color);
@@ -309,14 +311,14 @@ void RenderClxOutlinePixelsCheckLastColumn(
 		dst += width;
 	}
 	if (lastPixel) {
-		if (Fill) {
+		if constexpr (Fill) {
 			RenderOutlineForPixel<North, West, South, /*East=*/false>(dst++, dstPitch, color);
 		} else {
 			RenderOutlineForPixel<North, West, South, /*East=*/false, SkipColorIndexZero>(dst++, dstPitch, *src++, color);
 		}
 	}
 	if (oobPixel) {
-		if (Fill) {
+		if constexpr (Fill) {
 			RenderOutlineForPixel</*North=*/false, West, /*South=*/false, /*East=*/false>(dst, dstPitch, color);
 		} else {
 			RenderOutlineForPixel</*North=*/false, West, /*South=*/false, /*East=*/false, SkipColorIndexZero>(dst, dstPitch, *src, color);
@@ -329,16 +331,27 @@ void RenderClxOutlinePixels(
     uint8_t *dst, int dstPitch, int dstX, int dstW,
     const uint8_t *src, uint8_t width, uint8_t color)
 {
-	if (SkipColorIndexZero && Fill && *src == 0)
-		return;
+	if constexpr (SkipColorIndexZero && Fill) {
+		if (*src == 0)
+			return;
+	}
 
-	if (CheckFirstColumn && dstX <= 0) {
-		RenderClxOutlinePixelsCheckFirstColumn<Fill, North, West, South, East, SkipColorIndexZero>(
-		    dst, dstPitch, dstX, src, width, color);
-	} else if (CheckLastColumn && dstX + width >= dstW) {
-		RenderClxOutlinePixelsCheckLastColumn<Fill, North, West, South, East, SkipColorIndexZero>(
-		    dst, dstPitch, dstX, dstW, src, width, color);
-	} else if (Fill) {
+	if constexpr (CheckFirstColumn) {
+		if (dstX <= 0) {
+			RenderClxOutlinePixelsCheckFirstColumn<Fill, North, West, South, East, SkipColorIndexZero>(
+			    dst, dstPitch, dstX, src, width, color);
+			return;
+		}
+	}
+	if constexpr (CheckLastColumn) {
+		if (dstX + width >= dstW) {
+			RenderClxOutlinePixelsCheckLastColumn<Fill, North, West, South, East, SkipColorIndexZero>(
+			    dst, dstPitch, dstX, dstW, src, width, color);
+			return;
+		}
+	}
+
+	if constexpr (Fill) {
 		RenderOutlineForPixels<North, West, South, East>(dst, dstPitch, width, color);
 	} else {
 		RenderOutlineForPixels<North, West, South, East, SkipColorIndexZero>(dst, dstPitch, width, src, color);
@@ -370,7 +383,7 @@ const uint8_t *RenderClxOutlineRowClipped( // NOLINT(readability-function-cognit
 		dst += w;
 	};
 
-	if (ClipWidth) {
+	if constexpr (ClipWidth) {
 		auto remainingLeftClip = clipX.left - skipSize.xOffset;
 		if (skipSize.xOffset > clipX.left) {
 			position.x += static_cast<int>(skipSize.xOffset - clipX.left);
@@ -409,7 +422,11 @@ const uint8_t *RenderClxOutlineRowClipped( // NOLINT(readability-function-cognit
 		if (IsClxOpaque(v)) {
 			const bool fill = IsClxOpaqueFill(v);
 			v = fill ? GetClxOpaqueFillWidth(v) : GetClxOpaquePixelsWidth(v);
-			renderPixels(fill, ClipWidth ? std::min(remainingWidth, static_cast<int_fast16_t>(v)) : v);
+			if constexpr (ClipWidth) {
+				renderPixels(fill, std::min(remainingWidth, static_cast<int_fast16_t>(v)));
+			} else {
+				renderPixels(fill, v);
+			}
 		} else {
 			dst += v;
 		}
@@ -417,7 +434,7 @@ const uint8_t *RenderClxOutlineRowClipped( // NOLINT(readability-function-cognit
 		position.x += v;
 	}
 
-	if (ClipWidth) {
+	if constexpr (ClipWidth) {
 		remainingWidth += clipX.right;
 		if (remainingWidth > 0) {
 			skipSize.xOffset = static_cast<int_fast16_t>(srcWidth) - remainingWidth;
diff --git a/Source/engine/render/dun_render.cpp b/Source/engine/render/dun_render.cpp
index f9129474c..56b50c1e9 100644
--- a/Source/engine/render/dun_render.cpp
+++ b/Source/engine/render/dun_render.cpp
@@ -214,7 +214,7 @@ DVL_ALWAYS_INLINE DVL_ATTRIBUTE_HOT void RenderLineTransparent(uint8_t *DVL_REST
 template <LightType Light, bool Transparent>
 DVL_ALWAYS_INLINE DVL_ATTRIBUTE_HOT void RenderLineTransparentOrOpaque(uint8_t *DVL_RESTRICT dst, const uint8_t *DVL_RESTRICT src, uint_fast8_t width, const uint8_t *DVL_RESTRICT tbl)
 {
-	if (Transparent) {
+	if constexpr (Transparent) {
 		RenderLineTransparent<Light>(dst, src, width, tbl);
 	} else {
 		RenderLineOpaque<Light>(dst, src, width, tbl);
@@ -224,12 +224,12 @@ DVL_ALWAYS_INLINE DVL_ATTRIBUTE_HOT void RenderLineTransparentOrOpaque(uint8_t *
 template <LightType Light, bool OpaquePrefix, int8_t PrefixIncrement>
 DVL_ALWAYS_INLINE DVL_ATTRIBUTE_HOT void RenderLineTransparentAndOpaque(uint8_t *DVL_RESTRICT dst, const uint8_t *DVL_RESTRICT src, uint_fast8_t prefixWidth, uint_fast8_t width, const uint8_t *DVL_RESTRICT tbl)
 {
-	if (OpaquePrefix) {
+	if constexpr (OpaquePrefix) {
 		RenderLineOpaque<Light>(dst, src, prefixWidth, tbl);
-		if (!SkipTransparentPixels<OpaquePrefix, PrefixIncrement>)
+		if constexpr (!SkipTransparentPixels<OpaquePrefix, PrefixIncrement>)
 			RenderLineTransparent<Light>(dst + prefixWidth, src + prefixWidth, width - prefixWidth, tbl);
 	} else {
-		if (!SkipTransparentPixels<OpaquePrefix, PrefixIncrement>)
+		if constexpr (!SkipTransparentPixels<OpaquePrefix, PrefixIncrement>)
 			RenderLineTransparent<Light>(dst, src, prefixWidth, tbl);
 		RenderLineOpaque<Light>(dst + prefixWidth, src + prefixWidth, width - prefixWidth, tbl);
 	}
@@ -238,21 +238,21 @@ DVL_ALWAYS_INLINE DVL_ATTRIBUTE_HOT void RenderLineTransparentAndOpaque(uint8_t
 template <LightType Light, bool OpaquePrefix, int8_t PrefixIncrement>
 DVL_ALWAYS_INLINE DVL_ATTRIBUTE_HOT void RenderLine(uint8_t *DVL_RESTRICT dst, const uint8_t *DVL_RESTRICT src, uint_fast8_t n, const uint8_t *DVL_RESTRICT tbl, int8_t prefix)
 {
-	if (PrefixIncrement == 0) {
+	if constexpr (PrefixIncrement == 0) {
 		RenderLineTransparentOrOpaque<Light, OpaquePrefix>(dst, src, n, tbl);
 	} else if (prefix >= static_cast<int8_t>(n)) {
 		// We std::clamp the prefix to (0, n] and avoid calling `RenderLineTransparent/Opaque` with width=0.
-		if (OpaquePrefix) {
+		if constexpr (OpaquePrefix) {
 			RenderLineOpaque<Light>(dst, src, n, tbl);
 		} else {
-			if (!SkipTransparentPixels<OpaquePrefix, PrefixIncrement>)
+			if constexpr (!SkipTransparentPixels<OpaquePrefix, PrefixIncrement>)
 				RenderLineTransparent<Light>(dst, src, n, tbl);
 		}
 	} else if (prefix <= 0) {
-		if (!OpaquePrefix) {
+		if constexpr (!OpaquePrefix) {
 			RenderLineOpaque<Light>(dst, src, n, tbl);
 		} else {
-			if (!SkipTransparentPixels<OpaquePrefix, PrefixIncrement>)
+			if constexpr (!SkipTransparentPixels<OpaquePrefix, PrefixIncrement>)
 				RenderLineTransparent<Light>(dst, src, n, tbl);
 		}
 	} else {
@@ -727,13 +727,13 @@ DVL_ALWAYS_INLINE DVL_ATTRIBUTE_HOT void RenderRightTriangle(uint8_t *DVL_RESTRI
 
 template <LightType Light, bool OpaquePrefix, int8_t PrefixIncrement>
 DVL_ALWAYS_INLINE DVL_ATTRIBUTE_HOT void RenderTrapezoidUpperHalf(uint8_t *DVL_RESTRICT dst, uint16_t dstPitch, const uint8_t *DVL_RESTRICT src, const uint8_t *DVL_RESTRICT tbl) {
-	if (PrefixIncrement != 0) {
+	if constexpr (PrefixIncrement != 0) {
 		// The first and the last line are always fully transparent/opaque (or vice-versa).
 		// We handle them specially to avoid calling the blitter with width=0.
 		const uint8_t *srcEnd = src + Width * TrapezoidUpperHeight;
 		constexpr bool FirstLineIsTransparent = OpaquePrefix ^ (PrefixIncrement < 0);
-		if (FirstLineIsTransparent) {
-			if (!SkipTransparentPixels<OpaquePrefix, PrefixIncrement>)
+		if constexpr (FirstLineIsTransparent) {
+			if constexpr (!SkipTransparentPixels<OpaquePrefix, PrefixIncrement>)
 				RenderLineTransparent<Light>(dst, src, Width, tbl);
 		} else {
 			RenderLineOpaque<Light>(dst, src, Width, tbl);