Revert of added support for push_constant layout

src/sksl/SkSLMemoryLayout.h

-/*
- * Copyright 2016 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- 
-#ifndef SKIASL_MEMORYLAYOUT
-#define SKIASL_MEMORYLAYOUT
-
-#include "ir/SkSLType.h"
-
-namespace SkSL {
-
-class MemoryLayout {
-public:
-    enum Standard {
-        k140_Standard,
-        k430_Standard
-    };
-
-    MemoryLayout(Standard std) 
-    : fStd(std) {}
-
-    static size_t vector_alignment(size_t componentSize, int columns) {
-        return componentSize * (columns + columns % 2);
-    }
-
-    /** 
-     * Rounds up to the nearest multiple of 16 if in std140, otherwise returns the parameter
-     * unchanged (std140 requires various things to be rounded up to the nearest multiple of 16,
-     * std430 does not).
-     */
-    size_t roundUpIfNeeded(size_t raw) const {
-        switch (fStd) {
-            case k140_Standard: return (raw + 15) & ~15;
-            case k430_Standard: return raw;
-        }
-        ABORT("unreachable");
-    }
-
-    /**
-     * Returns a type's required alignment when used as a standalone variable.
-     */
-    size_t alignment(const Type& type) const {
-        // See OpenGL Spec 7.6.2.2 Standard Uniform Block Layout
-        switch (type.kind()) {
-            case Type::kScalar_Kind:
-                return this->size(type);
-            case Type::kVector_Kind:
-                return vector_alignment(this->size(type.componentType()), type.columns());
-            case Type::kMatrix_Kind:
-                return this->roundUpIfNeeded(vector_alignment(this->size(type.componentType()), 
-                                                              type.rows()));
-            case Type::kArray_Kind:
-                return this->roundUpIfNeeded(this->alignment(type.componentType()));
-            case Type::kStruct_Kind: {
-                size_t result = 0;
-                for (const auto& f : type.fields()) {
-                    size_t alignment = this->alignment(*f.fType);
-                    if (alignment > result) {
-                        result = alignment;
-                    }
-                }
-                return this->roundUpIfNeeded(result);
-            }
-            default:
-                ABORT(("cannot determine size of type " + type.name()).c_str());
-        }
-    }
-
-    /**
-     * For matrices and arrays, returns the number of bytes from the start of one entry (row, in
-     * the case of matrices) to the start of the next.
-     */
-    size_t stride(const Type& type) const {
-        switch (type.kind()) {
-            case Type::kMatrix_Kind: // fall through
-            case Type::kArray_Kind:
-                return this->alignment(type);
-            default:
-                ABORT("type does not have a stride");
-        }
-    }
-
-    /**
-     * Returns the size of a type in bytes.
-     */
-    size_t size(const Type& type) const {
-        switch (type.kind()) {
-            case Type::kScalar_Kind:
-                if (type.name() == "bool") {
-                    return 1;
-                }
-                // FIXME need to take precision into account, once we figure out how we want to
-                // handle it...
-                return 4;
-            case Type::kVector_Kind:
-                return type.columns() * this->size(type.componentType());
-            case Type::kMatrix_Kind: // fall through
-            case Type::kArray_Kind:
-                return type.columns() * this->stride(type);
-            case Type::kStruct_Kind: {
-                size_t total = 0;
-                for (const auto& f : type.fields()) {
-                    size_t alignment = this->alignment(*f.fType);
-                    if (total % alignment != 0) {
-                        total += alignment - total % alignment;
-                    }
-                    ASSERT(total % alignment == 0);
-                    total += this->size(*f.fType);
-                }
-                size_t alignment = this->alignment(type);
-                ASSERT(!type.fields().size() || 
-                       (0 == alignment % this->alignment(*type.fields()[0].fType)));
-                return (total + alignment - 1) & ~(alignment - 1);
-            }
-            default:
-                ABORT(("cannot determine size of type " + type.name()).c_str());
-        }
-    }
-
-    const Standard fStd;
-};
-
-} // namespace
-
-#endif