Implement Linker (module combiner)

Add extra iterators for ir::Module's sections
Add extra getters to ir::Function
Add a const version of BasicBlock::GetLabelInst()

Use the max of all inputs' version as version

Split debug in debug1 and debug2
- Debug1 instructions have to be placed before debug2 instructions.

Error out if different addressing or memory models are found

Exit early if no binaries were given

Error out if entry points are redeclared

Implement copy ctors for Function and BasicBlock
- Visual Studio ends up generating copy constructors that call deleted
  functions while compiling the linker code, while GCC and clang do not.
  So explicitly write those functions to avoid Visual Studio messing up.

Move removing duplicate capabilities to its own pass

Add functions running on all IDs present in an instruction

Remove duplicate SpvOpExtInstImport

Give default options value for link functions

Remove linkage capability if not making a library

Check types before allowing to link

Detect if two types/variables/functions have different decorations

Remove decorations of imported variables/functions and their types

Add a DecorationManager

Add a method for removing all decorations of id

Add methods for removing operands from instructions

Error out if one of the modules has a non-zero schema

Update README.md to talk about the linker

Do not freak out if an imported built-in variable has no export

2 files changed, 101 insertions, 0 deletions

diff --git a/include/spirv-tools/linker.hpp b/include/spirv-tools/linker.hpp
new file mode 100644
index 00000000..43c725da
--- /dev/null
+++ b/include/spirv-tools/linker.hpp
@@ -0,0 +1,98 @@
+// Copyright (c) 2017 Pierre Moreau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SPIRV_TOOLS_LINKER_HPP_
+#define SPIRV_TOOLS_LINKER_HPP_
+
+#include <cstdint>
+
+#include <memory>
+#include <vector>
+
+#include "libspirv.hpp"
+
+namespace spvtools {
+
+class LinkerOptions {
+ public:
+  LinkerOptions() : createLibrary_(false) {}
+
+  // Returns whether a library or an executable should be produced by the
+  // linking phase.
+  //
+  // All exported symbols are kept when creating a library, whereas they will
+  // be removed when creating an executable.
+  // The returned value will be true if creating a library, and false if
+  // creating an executable.
+  bool GetCreateLibrary() const { return createLibrary_; }
+  // Sets whether a library or an executable should be produced.
+  void SetCreateLibrary(bool create_library) {
+    createLibrary_ = create_library;
+  }
+
+ private:
+  bool createLibrary_;
+};
+
+class Linker {
+ public:
+  // Constructs an instance targeting the given environment |env|.
+  //
+  // The constructed instance will have an empty message consumer, which just
+  // ignores all messages from the library. Use SetMessageConsumer() to supply
+  // one if messages are of concern.
+  explicit Linker(spv_target_env env);
+
+  // Disables copy/move constructor/assignment operations.
+  Linker(const Linker&) = delete;
+  Linker(Linker&&) = delete;
+  Linker& operator=(const Linker&) = delete;
+  Linker& operator=(Linker&&) = delete;
+
+  // Destructs this instance.
+  ~Linker();
+
+  // Sets the message consumer to the given |consumer|. The |consumer| will be
+  // invoked once for each message communicated from the library.
+  void SetMessageConsumer(MessageConsumer consumer);
+
+  // Links one or more SPIR-V modules into a new SPIR-V module. That is,
+  // combine several SPIR-V modules into one, resolving link dependencies
+  // between them.
+  //
+  // At least one binary has to be provided in |binaries|. Those binaries do
+  // not have to be valid, but they should be at least parseable.
+  // The functions can fail due to the following:
+  // * No input modules were given;
+  // * One or more of those modules were not parseable;
+  // * The input modules used different addressing or memory models;
+  // * The ID or global variable number limit were exceeded;
+  // * Some entry points were defined multiple times;
+  // * Some imported symbols did not have an exported counterpart;
+  // * Possibly other reasons.
+  spv_result_t Link(const std::vector<std::vector<uint32_t>>& binaries,
+                    std::vector<uint32_t>& linked_binary,
+                    const LinkerOptions& options = LinkerOptions()) const;
+  spv_result_t Link(const uint32_t* const* binaries, const size_t* binary_sizes,
+                    size_t num_binaries, std::vector<uint32_t>& linked_binary,
+                    const LinkerOptions& options = LinkerOptions()) const;
+
+ private:
+  struct Impl;  // Opaque struct for holding the data fields used by this class.
+  std::unique_ptr<Impl> impl_;  // Unique pointer to implementation data.
+};
+
+}  // namespace spvtools
+
+#endif  // SPIRV_TOOLS_LINKER_HPP_
diff --git a/include/spirv-tools/optimizer.hpp b/include/spirv-tools/optimizer.hpp
index 7e1db252..e513120f 100644
--- a/include/spirv-tools/optimizer.hpp
+++ b/include/spirv-tools/optimizer.hpp
@@ -375,6 +375,9 @@ Optimizer::PassToken CreateAggressiveDCEPass();
 // The pass remaps result ids to a compact and gapless range starting from %1.
 Optimizer::PassToken CreateCompactIdsPass();
 
+// Creates a remove duplicate capabilities pass.
+Optimizer::PassToken CreateRemoveDuplicatesPass();
+
 }  // namespace spvtools
 
 #endif  // SPIRV_TOOLS_OPTIMIZER_HPP_