commit 2d5bbdc4d9de7bf12bb3da9cf87ca9c353ab6523
author Nicolas Capens <capn@google.com> Tue Sep 01 11:17:32 2020 -0400
committer Nicolas Capens <nicolascapens@google.com> Tue Sep 01 17:51:20 2020 +0000
tree bc188d11d349945b9a588dd53efd8e892f6621b9
parent efbc5caf2df7890a73072969685a03bb042a5a29

Assert multisample resolve has equal input and output formats

While our generic Blitter routine can handle resolving any multisample
format into any other format, the 'fastResolve()' method performs simple
per-component sample averaging, thus assuming the input and output
formats are identical.

This is also demanded by the Vulkan specification:
- vkCmdResolveImage: "srcImage and dstImage must have been created with
  the same image format."
- VkSubpassDescription: "each resolve attachment that is not
  VK_ATTACHMENT_UNUSED must have the same VkFormat as its corresponding
  color attachment."

This change adds an assert which would catch violations of that.

Bug: b/147802090
Change-Id: I23d2d463efbbaed04a782a0cf61b255bf1c25b03
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/48088
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>

src/Device/Blitter.cpp

diff --git a/src/Device/Blitter.cpp b/src/Device/Blitter.cpp
index 29767d1..f709c31 100644
--- a/src/Device/Blitter.cpp
+++ b/src/Device/Blitter.cpp
@@ -1882,6 +1882,17 @@
 
 void Blitter::resolve(const vk::Image *src, vk::Image *dst, VkImageResolve region)
 {
+	// "The aspectMask member of srcSubresource and dstSubresource must only contain VK_IMAGE_ASPECT_COLOR_BIT"
+	ASSERT(region.srcSubresource.aspectMask == VK_IMAGE_ASPECT_COLOR_BIT);
+	ASSERT(region.dstSubresource.aspectMask == VK_IMAGE_ASPECT_COLOR_BIT);
+	// "The layerCount member of srcSubresource and dstSubresource must match"
+	ASSERT(region.srcSubresource.layerCount == region.dstSubresource.layerCount);
+
+	// We use this method both for explicit resolves from vkCmdResolveImage, and implicit ones for resolve attachments.
+	// - vkCmdResolveImage: "srcImage and dstImage must have been created with the same image format."
+	// - VkSubpassDescription: "each resolve attachment that is not VK_ATTACHMENT_UNUSED must have the same VkFormat as its corresponding color attachment."
+	ASSERT(src->getFormat() == dst->getFormat());
+
 	if(fastResolve(src, dst, region))
 	{
 		return;
@@ -1913,11 +1924,6 @@
 
 bool Blitter::fastResolve(const vk::Image *src, vk::Image *dst, VkImageResolve region)
 {
-	// "The aspectMask member of srcSubresource and dstSubresource must only contain VK_IMAGE_ASPECT_COLOR_BIT"
-	ASSERT(region.srcSubresource.aspectMask == VK_IMAGE_ASPECT_COLOR_BIT);
-	ASSERT(region.dstSubresource.aspectMask == VK_IMAGE_ASPECT_COLOR_BIT);
-	ASSERT(region.srcSubresource.layerCount == region.dstSubresource.layerCount);
-
 	if(region.dstOffset != VkOffset3D{ 0, 0, 0 })
 	{
 		return false;