From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 8 Mar 2021 14:59:12 +0000 (+0200)
Subject: Recognize swizzles in GLSL
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=f526938b407e061c7424adedc34af4d1ff687f90

Recognize swizzles in GLSL
---

diff --git a/source/glsl/debug.cpp b/source/glsl/debug.cpp
index ee50bf46..fd1fd667 100644
--- a/source/glsl/debug.cpp
+++ b/source/glsl/debug.cpp
@@ -178,6 +178,16 @@ void DumpTree::visit(MemberAccess &memacc)
 	annotated_branch(text, *memacc.left);
 }
 
+void DumpTree::visit(Swizzle &swizzle)
+{
+	static const char components[4] = { 'x', 'y', 'z', 'w' };
+	string text = "Swizzle: .";
+	for(unsigned i=0; i<swizzle.count; ++i)
+		text += components[swizzle.components[i]];
+	text += format(" -> %s", format_type(swizzle.type));
+	annotated_branch(text, *swizzle.left);
+}
+
 void DumpTree::visit(UnaryExpression &unary)
 {
 	string text = format("Unary: %s, %sfix -> %s", unary.oper->token, (unary.oper->type==Operator::PREFIX ? "pre" : "post"), format_type(unary.type));
diff --git a/source/glsl/debug.h b/source/glsl/debug.h
index d873ea37..3837c569 100644
--- a/source/glsl/debug.h
+++ b/source/glsl/debug.h
@@ -58,6 +58,7 @@ private:
 	virtual void visit(VariableReference &);
 	virtual void visit(InterfaceBlockReference &);
 	virtual void visit(MemberAccess &);
+	virtual void visit(Swizzle &);
 	virtual void visit(UnaryExpression &);
 	virtual void visit(BinaryExpression &);
 	virtual void visit(Assignment &);
diff --git a/source/glsl/generate.cpp b/source/glsl/generate.cpp
index 53676c26..3e53c152 100644
--- a/source/glsl/generate.cpp
+++ b/source/glsl/generate.cpp
@@ -1,3 +1,4 @@
+#include <algorithm>
 #include <msp/core/hash.h>
 #include <msp/core/raii.h>
 #include <msp/strings/lexicalcast.h>
@@ -367,11 +368,43 @@ void VariableResolver::visit(MemberAccess &memacc)
 		if(i!=strct->members.variables.end())
 			declaration = i->second;
 	}
+	else if(BasicTypeDeclaration *basic = dynamic_cast<BasicTypeDeclaration *>(memacc.left->type))
+	{
+		bool scalar_swizzle = ((basic->kind==BasicTypeDeclaration::INT || basic->kind==BasicTypeDeclaration::FLOAT) && memacc.member.size()==1);
+		bool vector_swizzle = (basic->kind==BasicTypeDeclaration::VECTOR && memacc.member.size()<=4);
+		if(scalar_swizzle || vector_swizzle)
+		{
+			static const char component_names[] = { 'x', 'r', 's', 'y', 'g', 't', 'z', 'b', 'p', 'w', 'a', 'q' };
+
+			bool ok = true;
+			UInt8 components[4] = { };
+			for(unsigned i=0; (ok && i<memacc.member.size()); ++i)
+				ok = ((components[i] = (find(component_names, component_names+12, memacc.member[i])-component_names)/3) < 4);
+
+			if(ok)
+			{
+				Swizzle *swizzle = new Swizzle;
+				swizzle->source = memacc.source;
+				swizzle->line = memacc.line;
+				swizzle->oper = memacc.oper;
+				swizzle->left = memacc.left;
+				swizzle->component_group = memacc.member;
+				swizzle->count = memacc.member.size();
+				copy(components, components+memacc.member.size(), swizzle->components);
+				r_replacement_expr = swizzle;
+			}
+		}
+	}
 
 	r_any_resolved |= (declaration!=memacc.declaration);
 	memacc.declaration = declaration;
 }
 
+void VariableResolver::visit(Swizzle &swizzle)
+{
+	visit_and_replace(swizzle.left);
+}
+
 void VariableResolver::visit(UnaryExpression &unary)
 {
 	visit_and_replace(unary.expression);
@@ -589,6 +622,20 @@ void ExpressionResolver::visit(MemberAccess &memacc)
 		resolve(memacc, memacc.declaration->type_declaration, memacc.left->lvalue);
 }
 
+void ExpressionResolver::visit(Swizzle &swizzle)
+{
+	TraversingVisitor::visit(swizzle);
+
+	if(BasicTypeDeclaration *left_basic = dynamic_cast<BasicTypeDeclaration *>(swizzle.left->type))
+	{
+		BasicTypeDeclaration *left_elem = get_element_type(*left_basic);
+		if(swizzle.count==1)
+			resolve(swizzle, left_elem, swizzle.left->lvalue);
+		else if(left_basic->kind==BasicTypeDeclaration::VECTOR && left_elem)
+			resolve(swizzle, find_type(*left_elem, left_basic->kind, swizzle.count), swizzle.left->lvalue);
+	}
+}
+
 void ExpressionResolver::visit(UnaryExpression &unary)
 {
 	TraversingVisitor::visit(unary);
diff --git a/source/glsl/generate.h b/source/glsl/generate.h
index 427f4de2..c0d1ef8d 100644
--- a/source/glsl/generate.h
+++ b/source/glsl/generate.h
@@ -111,6 +111,7 @@ private:
 	virtual void visit(VariableReference &);
 	virtual void visit(InterfaceBlockReference &);
 	virtual void visit(MemberAccess &);
+	virtual void visit(Swizzle &);
 	virtual void visit(UnaryExpression &);
 	virtual void visit(BinaryExpression &);
 	virtual void visit(Assignment &);
@@ -157,6 +158,7 @@ private:
 	virtual void visit(VariableReference &);
 	virtual void visit(InterfaceBlockReference &);
 	virtual void visit(MemberAccess &);
+	virtual void visit(Swizzle &);
 	virtual void visit(UnaryExpression &);
 	void visit(BinaryExpression &, bool);
 	virtual void visit(BinaryExpression &);
diff --git a/source/glsl/optimize.cpp b/source/glsl/optimize.cpp
index c1431f2b..414cf387 100644
--- a/source/glsl/optimize.cpp
+++ b/source/glsl/optimize.cpp
@@ -232,6 +232,11 @@ void FunctionInliner::visit(MemberAccess &memacc)
 	visit_and_inline(memacc.left);
 }
 
+void FunctionInliner::visit(Swizzle &swizzle)
+{
+	visit_and_inline(swizzle.left);
+}
+
 void FunctionInliner::visit(FunctionCall &call)
 {
 	for(NodeArray<Expression>::iterator i=call.arguments.begin(); i!=call.arguments.end(); ++i)
@@ -439,6 +444,13 @@ void ExpressionInliner::visit(MemberAccess &memacc)
 	r_trivial = false;
 }
 
+void ExpressionInliner::visit(Swizzle &swizzle)
+{
+	visit_and_record(swizzle.left, swizzle.oper, false);
+	r_oper = swizzle.oper;
+	r_trivial = false;
+}
+
 void ExpressionInliner::visit(UnaryExpression &unary)
 {
 	SetFlag set_target(mutating, mutating || unary.oper->token[1]=='+' || unary.oper->token[1]=='-');
@@ -752,6 +764,13 @@ void UnusedVariableRemover::visit(MemberAccess &memacc)
 	unused_nodes.erase(memacc.declaration);
 }
 
+void UnusedVariableRemover::visit(Swizzle &swizzle)
+{
+	if(assignment_target)
+		r_assign_to_subfield = true;
+	TraversingVisitor::visit(swizzle);
+}
+
 void UnusedVariableRemover::visit(UnaryExpression &unary)
 {
 	TraversingVisitor::visit(unary);
diff --git a/source/glsl/optimize.h b/source/glsl/optimize.h
index 551e2d56..67d064c5 100644
--- a/source/glsl/optimize.h
+++ b/source/glsl/optimize.h
@@ -90,6 +90,7 @@ private:
 	virtual void visit(BinaryExpression &);
 	virtual void visit(Assignment &a) { visit(static_cast<BinaryExpression &>(a)); }
 	virtual void visit(MemberAccess &);
+	virtual void visit(Swizzle &);
 	virtual void visit(FunctionCall &);
 	virtual void visit(ExpressionStatement &);
 	virtual void visit(VariableDeclaration &);
@@ -139,6 +140,7 @@ private:
 	virtual void visit(Block &);
 	virtual void visit(VariableReference &);
 	virtual void visit(MemberAccess &);
+	virtual void visit(Swizzle &);
 	virtual void visit(UnaryExpression &);
 	virtual void visit(BinaryExpression &);
 	virtual void visit(Assignment &);
@@ -223,6 +225,7 @@ private:
 	virtual void visit(VariableReference &);
 	virtual void visit(InterfaceBlockReference &);
 	virtual void visit(MemberAccess &);
+	virtual void visit(Swizzle &);
 	virtual void visit(UnaryExpression &);
 	virtual void visit(BinaryExpression &);
 	virtual void visit(Assignment &);
diff --git a/source/glsl/output.cpp b/source/glsl/output.cpp
index 52371d1b..b277ba8e 100644
--- a/source/glsl/output.cpp
+++ b/source/glsl/output.cpp
@@ -136,6 +136,12 @@ void Formatter::visit(MemberAccess &memacc)
 	append(format(".%s", memacc.member));
 }
 
+void Formatter::visit(Swizzle &swizzle)
+{
+	swizzle.left->visit(*this);
+	append(format(".%s", swizzle.component_group));
+}
+
 void Formatter::visit(UnaryExpression &unary)
 {
 	if(unary.oper->type==Operator::PREFIX)
diff --git a/source/glsl/output.h b/source/glsl/output.h
index f720606e..61c02caa 100644
--- a/source/glsl/output.h
+++ b/source/glsl/output.h
@@ -38,6 +38,7 @@ private:
 	virtual void visit(VariableReference &);
 	virtual void visit(InterfaceBlockReference &);
 	virtual void visit(MemberAccess &);
+	virtual void visit(Swizzle &);
 	virtual void visit(UnaryExpression &);
 	virtual void visit(BinaryExpression &);
 	virtual void visit(Assignment &);
diff --git a/source/glsl/syntax.cpp b/source/glsl/syntax.cpp
index cb774197..85d805d1 100644
--- a/source/glsl/syntax.cpp
+++ b/source/glsl/syntax.cpp
@@ -161,6 +161,18 @@ void MemberAccess::visit(NodeVisitor &visitor)
 }
 
 
+Swizzle::Swizzle():
+	count(0)
+{
+	fill(components, components+4, 0);
+}
+
+void Swizzle::visit(NodeVisitor &visitor)
+{
+	visitor.visit(*this);
+}
+
+
 void UnaryExpression::visit(NodeVisitor &visitor)
 {
 	visitor.visit(*this);
diff --git a/source/glsl/syntax.h b/source/glsl/syntax.h
index 30acca42..c3eeb6a1 100644
--- a/source/glsl/syntax.h
+++ b/source/glsl/syntax.h
@@ -6,6 +6,7 @@
 #include <set>
 #include <string>
 #include <vector>
+#include <msp/core/inttypes.h>
 #include <msp/core/refptr.h>
 #include <msp/core/variant.h>
 #include "features.h"
@@ -197,6 +198,19 @@ struct MemberAccess: Expression
 	virtual void visit(NodeVisitor &);
 };
 
+struct Swizzle: Expression
+{
+	NodePtr<Expression> left;
+	std::string component_group;
+	unsigned count;
+	UInt8 components[4];
+
+	Swizzle();
+
+	virtual Swizzle *clone() const { return new Swizzle(*this); }
+	virtual void visit(NodeVisitor &);
+};
+
 struct UnaryExpression: Expression
 {
 	NodePtr<Expression> expression;
diff --git a/source/glsl/validate.cpp b/source/glsl/validate.cpp
index b0c6e3d6..c4e0a9bd 100644
--- a/source/glsl/validate.cpp
+++ b/source/glsl/validate.cpp
@@ -1,3 +1,4 @@
+#include <algorithm>
 #include <cstring>
 #include <msp/core/raii.h>
 #include <msp/strings/format.h>
@@ -227,6 +228,44 @@ void ReferenceValidator::visit(FunctionDeclaration &func)
 }
 
 
+void ExpressionValidator::visit(Swizzle &swizzle)
+{
+	unsigned size = 0;
+	if(BasicTypeDeclaration *basic = dynamic_cast<BasicTypeDeclaration *>(swizzle.left->type))
+	{
+		if(basic->kind==BasicTypeDeclaration::INT || basic->kind==BasicTypeDeclaration::FLOAT)
+			size = 1;
+		else if(basic->kind==BasicTypeDeclaration::VECTOR)
+			size = basic->size;
+	}
+
+	if(size)
+	{
+		static const char component_names[] = { 'x', 'y', 'z', 'w', 'r', 'g', 'b', 'a', 's', 't', 'p', 'q' };
+		int flavour = -1;
+		for(unsigned i=0; i<swizzle.count; ++i)
+		{
+			unsigned component_flavour = (find(component_names, component_names+12, swizzle.component_group[i])-component_names)/4;
+			if(flavour==-1)
+				flavour = component_flavour;
+			else if(flavour>=0 && component_flavour!=static_cast<unsigned>(flavour))
+			{
+				error(swizzle, format("Flavour of swizzle component '%c' is inconsistent with '%c'",
+					swizzle.component_group[i], swizzle.component_group[0]));
+				flavour = -2;
+			}
+
+			if(swizzle.components[i]>=size)
+				error(swizzle, format("Access to component '%c' which is not present in '%s'",
+					swizzle.component_group[i], swizzle.left->type->name));
+		}
+	}
+	else if(swizzle.left->type)
+		error(swizzle, format("Swizzle applied to '%s' which is neither a scalar nor a vector", swizzle.left->type->name));
+
+	TraversingVisitor::visit(swizzle);
+}
+
 void ExpressionValidator::visit(UnaryExpression &unary)
 {
 	if(unary.expression->type)
diff --git a/source/glsl/validate.h b/source/glsl/validate.h
index e5b8ed4e..2efb5199 100644
--- a/source/glsl/validate.h
+++ b/source/glsl/validate.h
@@ -88,6 +88,7 @@ public:
 	void apply(Stage &s) { stage = &s; s.content.visit(*this); }
 
 private:
+	virtual void visit(Swizzle &);
 	virtual void visit(UnaryExpression &);
 	virtual void visit(BinaryExpression &);
 	virtual void visit(Assignment &);
diff --git a/source/glsl/visitor.cpp b/source/glsl/visitor.cpp
index ebcedb71..dfe2d8d4 100644
--- a/source/glsl/visitor.cpp
+++ b/source/glsl/visitor.cpp
@@ -26,6 +26,11 @@ void TraversingVisitor::visit(MemberAccess &memacc)
 	memacc.left->visit(*this);
 }
 
+void TraversingVisitor::visit(Swizzle &swizzle)
+{
+	swizzle.left->visit(*this);
+}
+
 void TraversingVisitor::visit(UnaryExpression &unary)
 {
 	unary.expression->visit(*this);
diff --git a/source/glsl/visitor.h b/source/glsl/visitor.h
index 30b9b484..30ab2544 100644
--- a/source/glsl/visitor.h
+++ b/source/glsl/visitor.h
@@ -23,6 +23,7 @@ public:
 	virtual void visit(VariableReference &) { }
 	virtual void visit(InterfaceBlockReference &) { }
 	virtual void visit(MemberAccess &) { }
+	virtual void visit(Swizzle &) { }
 	virtual void visit(UnaryExpression &) { }
 	virtual void visit(BinaryExpression &) { }
 	virtual void visit(Assignment &) { }
@@ -58,6 +59,7 @@ public:
 	virtual void visit(Block &);
 	virtual void visit(ParenthesizedExpression &);
 	virtual void visit(MemberAccess &);
+	virtual void visit(Swizzle &);
 	virtual void visit(UnaryExpression &);
 	virtual void visit(BinaryExpression &);
 	virtual void visit(Assignment &);
diff --git a/tests/glsl/invalid_swizzle.glsl b/tests/glsl/invalid_swizzle.glsl
new file mode 100644
index 00000000..4094ce51
--- /dev/null
+++ b/tests/glsl/invalid_swizzle.glsl
@@ -0,0 +1,15 @@
+#pragma MSP stage(vertex)
+layout(location=0) in vec4 position;
+layout(location=1) in vec2 texcoord;
+void main()
+{
+	vec2 bad_component = texcoord.xz;
+	vec4 mixed = position.xyba;
+	gl_Position = position.xyzwx.xyzw;
+}
+
+/* Expected error:
+<test>:6: Access to component 'z' which is not present in 'vec2'
+<test>:7: Flavour of swizzle component 'b' is inconsistent with 'x'
+<test>:8: Use of undeclared member 'xyzwx'
+*/