1 files changed, 101 insertions, 0 deletions
diff --git a/gfx/angle/checkout/src/compiler/translator/tree_ops/ForcePrecisionQualifier.cpp b/gfx/angle/checkout/src/compiler/translator/tree_ops/ForcePrecisionQualifier.cpp
new file mode 100644
index 0000000000..00dd0131c6
--- /dev/null
+++ b/gfx/angle/checkout/src/compiler/translator/tree_ops/ForcePrecisionQualifier.cpp
@@ -0,0 +1,101 @@
+//
+// Copyright 2020 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+
+#include "compiler/translator/tree_ops/ForcePrecisionQualifier.h"
+#include "angle_gl.h"
+#include "common/debug.h"
+#include "compiler/translator/Compiler.h"
+#include "compiler/translator/tree_util/IntermTraverse.h"
+#include "compiler/translator/util.h"
+
+namespace sh
+{
+
+namespace
+{
+class TPrecisionTraverser : public TIntermTraverser
+{
+  public:
+    TPrecisionTraverser(TSymbolTable *symbolTable);
+
+  protected:
+    bool visitDeclaration(Visit visit, TIntermDeclaration *node) override;
+
+    void overwriteVariablePrecision(TType *type) const;
+};
+
+TPrecisionTraverser::TPrecisionTraverser(TSymbolTable *symbolTable)
+    : TIntermTraverser(true, true, true, symbolTable)
+{}
+
+void TPrecisionTraverser::overwriteVariablePrecision(TType *type) const
+{
+    if (type->getPrecision() == EbpHigh)
+    {
+        type->setPrecision(EbpMedium);
+    }
+}
+
+bool TPrecisionTraverser::visitDeclaration(Visit visit, TIntermDeclaration *node)
+{
+    // Variable declaration.
+    if (visit == PreVisit)
+    {
+        const TIntermSequence &sequence = *(node->getSequence());
+        TIntermTyped *variable          = sequence.front()->getAsTyped();
+        const TType &type               = variable->getType();
+        TQualifier qualifier            = variable->getQualifier();
+
+        // Don't modify uniform since it might be shared between vertex and fragment shader
+        if (qualifier == EvqUniform)
+        {
+            return true;
+        }
+
+        // Visit the struct.
+        if (type.isStructSpecifier())
+        {
+            const TStructure *structure = type.getStruct();
+            const TFieldList &fields    = structure->fields();
+            for (size_t i = 0; i < fields.size(); ++i)
+            {
+                const TField *field    = fields[i];
+                const TType *fieldType = field->type();
+                overwriteVariablePrecision((TType *)fieldType);
+            }
+        }
+        else if (type.getBasicType() == EbtInterfaceBlock)
+        {
+            const TInterfaceBlock *interfaceBlock = type.getInterfaceBlock();
+            const TFieldList &fields              = interfaceBlock->fields();
+            for (const TField *field : fields)
+            {
+                const TType *fieldType = field->type();
+                overwriteVariablePrecision((TType *)fieldType);
+            }
+        }
+        else
+        {
+            overwriteVariablePrecision((TType *)&type);
+        }
+    }
+    return true;
+}
+}  // namespace
+
+bool ForceShaderPrecisionToMediump(TIntermNode *root, TSymbolTable *symbolTable, GLenum shaderType)
+{
+    if (shaderType != GL_FRAGMENT_SHADER)
+    {
+        return true;
+    }
+
+    TPrecisionTraverser traverser(symbolTable);
+    root->traverse(&traverser);
+    return true;
+}
+
+}  // namespace sh