From 8df956b03639acbaf0e14b483295cdb7c23cac05 Mon Sep 17 00:00:00 2001
From: "Unknown W. Brackets" <checkins@unknownbrackets.org>
Date: Sun, 2 Oct 2022 07:32:31 -0700
Subject: [PATCH] Vulkan: Block geometry shaders on older Mali.

They're too slow to be usable.
---
 Common/GPU/Vulkan/thin3d_vulkan.cpp | 5 +++++
 Common/GPU/thin3d.h                 | 3 +++
 GPU/Vulkan/GPU_Vulkan.cpp           | 2 +-
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/Common/GPU/Vulkan/thin3d_vulkan.cpp b/Common/GPU/Vulkan/thin3d_vulkan.cpp
index 413057b288..06e026d35c 100644
--- a/Common/GPU/Vulkan/thin3d_vulkan.cpp
+++ b/Common/GPU/Vulkan/thin3d_vulkan.cpp
@@ -846,6 +846,11 @@ VKContext::VKContext(VulkanContext *vulkan)
 		if (majorVersion >= 32) {
 			bugs_.Infest(Bugs::MALI_CONSTANT_LOAD_BUG);  // See issue #15661
 		}
+
+		// Older ARM devices have very slow geometry shaders, not worth using.  At least before 15.
+		if (majorVersion <= 15) {
+			bugs_.Infest(Bugs::GEOMETRY_SHADERS_SLOW);
+		}
 	}
 
 	// Limited, through input attachments and self-dependencies.
diff --git a/Common/GPU/thin3d.h b/Common/GPU/thin3d.h
index f0c562b2f3..c04b7119cd 100644
--- a/Common/GPU/thin3d.h
+++ b/Common/GPU/thin3d.h
@@ -333,11 +333,14 @@ public:
 		RASPBERRY_SHADER_COMP_HANG = 8,
 		MALI_CONSTANT_LOAD_BUG = 9,
 		SUBPASS_FEEDBACK_BROKEN = 10,
+		GEOMETRY_SHADERS_SLOW = 11,
 		MAX_BUG,
 	};
 
 protected:
 	uint32_t flags_ = 0;
+
+	static_assert(sizeof(flags_) * 8 > MAX_BUG, "Ran out of space for bugs.");
 };
 
 class RefCountedObject {
diff --git a/GPU/Vulkan/GPU_Vulkan.cpp b/GPU/Vulkan/GPU_Vulkan.cpp
index 6376fc0620..6d91a3b20e 100644
--- a/GPU/Vulkan/GPU_Vulkan.cpp
+++ b/GPU/Vulkan/GPU_Vulkan.cpp
@@ -233,7 +233,7 @@ u32 GPU_Vulkan::CheckGPUFeatures() const {
 	}
 
 	// Fall back to geometry shader culling if we can't do vertex range culling.
-	if (enabledFeatures.geometryShader) {
+	if (enabledFeatures.geometryShader && !draw_->GetBugs().Has(Draw::Bugs::GEOMETRY_SHADERS_SLOW)) {
 		const bool vertexSupported = draw_->GetDeviceCaps().clipDistanceSupported && draw_->GetDeviceCaps().cullDistanceSupported;
 		if (!vertexSupported || (features & GPU_SUPPORTS_VS_RANGE_CULLING) == 0) {
 			// Switch to culling via the geometry shader if not fully supported in vertex.