From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 7 Nov 2021 14:06:09 +0000 (+0200)
Subject: Generate correct OpPhi instructions for nested ternary expressions
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=b125c684e2c2feb86845f051285fe666d8ebfc76

Generate correct OpPhi instructions for nested ternary expressions

The parent blocks must be immediate predecessors of the block containing
the OpPhi instruction.
---

diff --git a/source/glsl/spirv.cpp b/source/glsl/spirv.cpp
index 91182a65..39aa9a06 100644
--- a/source/glsl/spirv.cpp
+++ b/source/glsl/spirv.cpp
@@ -1028,11 +1028,13 @@ void SpirVGenerator::visit(TernaryExpression &ternary)
 	writer.write_op_label(true_label_id);
 	ternary.true_expr->visit(*this);
 	Id true_result_id = r_expression_result_id;
+	true_label_id = writer.get_current_block();
 	writer.write_op(content.function_body, OP_BRANCH, merge_block_id);
 
 	writer.write_op_label(false_label_id);
 	ternary.false_expr->visit(*this);
 	Id false_result_id = r_expression_result_id;
+	false_label_id = writer.get_current_block();
 
 	writer.write_op_label(merge_block_id);
 	r_expression_result_id = begin_expression(OP_PHI, get_id(*ternary.type), 4);
@@ -1819,7 +1821,7 @@ void SpirVGenerator::visit(FunctionDeclaration &func)
 	SetForScope<FunctionDeclaration *> set_func(current_function, &func);
 	func.body.visit(*this);
 
-	if(writer.has_current_block())
+	if(writer.get_current_block())
 	{
 		if(!reachable)
 			writer.write_op(content.function_body, OP_UNREACHABLE);
@@ -1848,7 +1850,7 @@ void SpirVGenerator::visit(Conditional &cond)
 
 	writer.write_op_label(true_label_id);
 	cond.body.visit(*this);
-	if(writer.has_current_block())
+	if(writer.get_current_block())
 		writer.write_op(content.function_body, OP_BRANCH, merge_block_id);
 
 	bool reachable_if_true = reachable;
diff --git a/source/glsl/spirvwriter.h b/source/glsl/spirvwriter.h
index 95db13c1..8456389a 100644
--- a/source/glsl/spirvwriter.h
+++ b/source/glsl/spirvwriter.h
@@ -61,7 +61,7 @@ public:
 	void write_op_member_decorate(Id, unsigned, Decoration);
 	void write_op_member_decorate(Id, unsigned, Decoration, Word);
 	void write_op_label(Id);
-	bool has_current_block() const { return current_block_id; }
+	Id get_current_block() const { return current_block_id; }
 	void begin_function_body(Id);
 	void end_function_body();
 	void finalize(unsigned, Id);
diff --git a/tests/glsl/nested_ternary.glsl b/tests/glsl/nested_ternary.glsl
new file mode 100644
index 00000000..8896c17a
--- /dev/null
+++ b/tests/glsl/nested_ternary.glsl
@@ -0,0 +1,49 @@
+uniform Colors
+{
+	vec4 top_left;
+	vec4 top_right;
+	vec4 bottom_left;
+	vec4 bottom_right;
+};
+
+#pragma MSP stage(vertex)
+layout(location=0) in vec4 position;
+void main()
+{
+	gl_Position = position;
+	passthrough;
+}
+
+#pragma MSP stage(fragment)
+layout(location=0) out vec4 frag_color;
+void main()
+{
+	frag_color = (position.x>0 ? position.y>0 ? top_right : bottom_right :
+		position.y>0 ? top_left : bottom_left);
+}
+
+/* Expected output: vertex
+layout(location=0) in vec4 position;
+layout(location=0) out vec4 _vs_out_position;
+void main()
+{
+	gl_Position = position;
+	_vs_out_position = position;
+}
+*/
+
+/* Expected output: fragment
+layout(binding=23) uniform Colors
+{
+	vec4 top_left;
+	vec4 top_right;
+	vec4 bottom_left;
+	vec4 bottom_right;
+};
+layout(location=0) out vec4 frag_color;
+layout(location=0) in vec4 _vs_out_position;
+void main()
+{
+	frag_color = _vs_out_position.x>0.0?(_vs_out_position.y>0.0?top_right:bottom_right):_vs_out_position.y>0.0?top_left:bottom_left;
+}
+*/