From 0d5ff7918d50092d8cf2e1b8f7af1d7d29b6eb9b Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 17 Nov 2021 15:34:53 +0200
Subject: [PATCH] Use OriginUpperLeft execution mode on Vulkan as required by
 the spec

---
 source/glsl/compiler.cpp     | 2 +-
 source/glsl/spirv.cpp        | 8 ++++++--
 source/glsl/spirv.h          | 3 ++-
 source/glsl/spirvconstants.h | 1 +
 4 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/source/glsl/compiler.cpp b/source/glsl/compiler.cpp
index a447c9c9..0e26a163 100644
--- a/source/glsl/compiler.cpp
+++ b/source/glsl/compiler.cpp
@@ -158,7 +158,7 @@ vector<uint32_t> Compiler::get_combined_spirv() const
 	if(!compiled)
 		throw invalid_operation("Compiler::get_combined_spirv");
 	SpirVGenerator gen;
-	gen.apply(*module);
+	gen.apply(*module, features);
 	return gen.get_code();
 }
 
diff --git a/source/glsl/spirv.cpp b/source/glsl/spirv.cpp
index 13c58a69..7f99ebb3 100644
--- a/source/glsl/spirv.cpp
+++ b/source/glsl/spirv.cpp
@@ -135,8 +135,9 @@ SpirVGenerator::SpirVGenerator():
 	writer(content)
 { }
 
-void SpirVGenerator::apply(Module &module)
+void SpirVGenerator::apply(Module &module, const Features &f)
 {
+	features = f;
 	use_capability(CAP_SHADER);
 
 	for(Stage &s: module.stages)
@@ -1745,7 +1746,10 @@ void SpirVGenerator::visit_entry_point(FunctionDeclaration &func, Id func_id)
 	writer.end_op(OP_ENTRY_POINT);
 
 	if(stage->type==Stage::FRAGMENT)
-		writer.write_op(content.exec_modes, OP_EXECUTION_MODE, func_id, EXEC_ORIGIN_LOWER_LEFT);
+	{
+		SpirVExecutionMode origin = (features.target_api==VULKAN ? EXEC_ORIGIN_UPPER_LEFT : EXEC_ORIGIN_LOWER_LEFT);
+		writer.write_op(content.exec_modes, OP_EXECUTION_MODE, func_id, origin);
+	}
 	else if(stage->type==Stage::GEOMETRY)
 		use_capability(CAP_GEOMETRY);
 
diff --git a/source/glsl/spirv.h b/source/glsl/spirv.h
index 59c7b50b..addf8970 100644
--- a/source/glsl/spirv.h
+++ b/source/glsl/spirv.h
@@ -70,6 +70,7 @@ private:
 		bool operator<(const ConstantKey &) const;
 	};
 
+	Features features;
 	Stage *stage = 0;
 	FunctionDeclaration *current_function = 0;
 	std::vector<const InterfaceLayout *> interface_layouts;
@@ -106,7 +107,7 @@ private:
 public:
 	SpirVGenerator();
 
-	void apply(Module &);
+	void apply(Module &, const Features &);
 	const std::vector<Word> &get_code() const { return content.code; }
 
 private:
diff --git a/source/glsl/spirvconstants.h b/source/glsl/spirvconstants.h
index 33d705e2..9935b43e 100644
--- a/source/glsl/spirvconstants.h
+++ b/source/glsl/spirvconstants.h
@@ -169,6 +169,7 @@ enum SpirVCapability
 
 enum SpirVExecutionMode
 {
+	EXEC_ORIGIN_UPPER_LEFT = 7,
 	EXEC_ORIGIN_LOWER_LEFT = 8,
 	EXEC_INPUT_POINTS = 19,
 	EXEC_INPUT_LINES = 20,
-- 
2.43.0