added DSL Modifiers

Change-Id: Ie1b0b8068b487905691b20e318c7898653763a25
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/359757
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>

src/sksl/dsl/DSL.h

@@ -16,6 +16,7 @@ namespace dsl {
 
 using Block = DSLBlock;
 using Expression = DSLExpression;
+using Modifiers = DSLModifiers;
 using Statement = DSLStatement;
 using Var = DSLVar;
 

src/sksl/dsl/DSLModifiers.h

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SKSL_DSL_MODIFIERS
+#define SKSL_DSL_MODIFIERS
+
+#include "src/sksl/ir/SkSLModifiers.h"
+namespace SkSL {
+
+namespace dsl {
+
+enum Modifier {
+    kNo_Modifier            =       0,
+    kConst_Modifier         = 1 <<  0,
+    kIn_Modifier            = 1 <<  1,
+    kOut_Modifier           = 1 <<  2,
+    kInOut_Modifier         = kIn_Modifier | kOut_Modifier,
+    kUniform_Modifier       = 1 <<  3,
+    kFlat_Modifier          = 1 <<  4,
+    kNoPerspective_Modifier = 1 <<  5,
+};
+
+class DSLModifiers {
+public:
+
+    DSLModifiers() {}
+
+    DSLModifiers(int flags)
+        : fModifiers(SkSL::Layout(), flags) {}
+
+private:
+    SkSL::Modifiers fModifiers;
+
+    friend class DSLVar;
+};
+
+} // namespace dsl
+
+} // namespace SkSL
+
+#endif

src/sksl/dsl/DSLVar.cpp

@@ -8,6 +8,7 @@
 #include "src/sksl/dsl/DSLVar.h"
 
 #include "src/sksl/SkSLUtil.h"
+#include "src/sksl/dsl/DSLModifiers.h"
 #include "src/sksl/dsl/DSLType.h"
 #include "src/sksl/dsl/priv/DSLWriter.h"
 #include "src/sksl/ir/SkSLBinaryExpression.h"
@@ -27,12 +28,14 @@ DSLVar::DSLVar(const char* name)
 }
 
 DSLVar::DSLVar(DSLType type, const char* name)
+    : DSLVar(DSLModifiers(), std::move(type), name) {}
+
+DSLVar::DSLVar(DSLModifiers modifiers, DSLType type, const char* name)
     : fName(DSLWriter::Name(name)) {
-    Modifiers modifiers;
-    DSLWriter::IRGenerator().checkVarDeclaration(/*offset=*/-1, modifiers, &type.skslType(),
-                                                 Variable::Storage::kLocal);
+    DSLWriter::IRGenerator().checkVarDeclaration(/*offset=*/-1, modifiers.fModifiers,
+                                                 &type.skslType(), Variable::Storage::kLocal);
     fDeclaration = DSLWriter::IRGenerator().convertVarDeclaration(/*offset=*/-1,
-                                                                  modifiers,
+                                                                  modifiers.fModifiers,
                                                                   &type.skslType(),
                                                                   fName,
                                                                   /*isArray=*/false,

src/sksl/dsl/DSLVar.h

@@ -9,6 +9,7 @@
 #define SKSL_DSL_VAR
 
 #include "src/sksl/dsl/DSLExpression.h"
+#include "src/sksl/dsl/DSLModifiers.h"
 
 namespace SkSL {
 
@@ -28,6 +29,8 @@ public:
      */
     DSLVar(DSLType type, const char* name = "var");
 
+    DSLVar(DSLModifiers modifiers, DSLType type, const char* name = "var");
+
     DSLVar(DSLVar&&) = delete;
 
     DSLExpression x() {

src/sksl/dsl/priv/DSLWriter.cpp

@@ -112,6 +112,10 @@ void DSLWriter::ReportError(const char* msg) {
     }
 }
 
+const SkSL::Variable& DSLWriter::Var(const DSLVar& var) {
+    return *var.var();
+}
+
 #if !SK_SUPPORT_GPU || defined(SKSL_STANDALONE)
 
 DSLWriter& DSLWriter::Instance() {

src/sksl/dsl/priv/DSLWriter.h

@@ -69,6 +69,11 @@ public:
      */
     static const SkSL::Modifiers* Modifiers(SkSL::Modifiers modifiers);
 
+    /**
+     * Returns the SkSL variable corresponding to a DSLVar.
+     */
+    static const SkSL::Variable& Var(const DSLVar& var);
+
     /**
      * Returns the (possibly mangled) final name that should be used for an entity with the given
      * raw name.

tests/SkSLDSLTest.cpp

@@ -1111,3 +1111,38 @@ DEF_GPUTEST_FOR_MOCK_CONTEXT(DSLBuiltins, r, ctxInfo) {
         Ceil(a == b).release();
     }
 }
+
+DEF_GPUTEST_FOR_MOCK_CONTEXT(DSLModifiers, r, ctxInfo) {
+    AutoDSLContext context(ctxInfo.directContext()->priv().getGpu());
+
+    Var v1(kConst_Modifier, kInt, "v1");
+    Statement d1 = Declare(v1);
+    REPORTER_ASSERT(r, d1.release()->description() == "const int v1;");
+
+    // Most modifiers require an appropriate context to be legal. We can't yet give them that
+    // context, so we can't as yet Declare() variables with these modifiers.
+    // TODO: better tests when able
+    Var v2(kIn_Modifier, kInt, "v2");
+    REPORTER_ASSERT(r, DSLWriter::Var(v2).modifiers().fFlags == SkSL::Modifiers::kIn_Flag);
+
+    Var v3(kOut_Modifier, kInt, "v3");
+    REPORTER_ASSERT(r, DSLWriter::Var(v3).modifiers().fFlags == SkSL::Modifiers::kOut_Flag);
+
+    Var v4(kUniform_Modifier, kInt, "v4");
+    REPORTER_ASSERT(r, DSLWriter::Var(v4).modifiers().fFlags == SkSL::Modifiers::kUniform_Flag);
+
+    Var v5(kFlat_Modifier, kInt, "v5");
+    REPORTER_ASSERT(r, DSLWriter::Var(v5).modifiers().fFlags == SkSL::Modifiers::kFlat_Flag);
+
+    Var v6(kNoPerspective_Modifier, kInt, "v6");
+    REPORTER_ASSERT(r, DSLWriter::Var(v6).modifiers().fFlags ==
+                       SkSL::Modifiers::kNoPerspective_Flag);
+
+    Var v7(kIn_Modifier | kOut_Modifier, kInt, "v7");
+    REPORTER_ASSERT(r, DSLWriter::Var(v7).modifiers().fFlags ==
+                       (SkSL::Modifiers::kIn_Flag | SkSL::Modifiers::kOut_Flag));
+
+    Var v8(kInOut_Modifier, kInt, "v8");
+    REPORTER_ASSERT(r, DSLWriter::Var(v8).modifiers().fFlags ==
+                       (SkSL::Modifiers::kIn_Flag | SkSL::Modifiers::kOut_Flag));
+}