1 files changed, 93 insertions, 0 deletions
diff --git a/tools/opt/Passes.cpp b/tools/opt/Passes.cpp
new file mode 100644
index 0000000000..49751269df
--- /dev/null
+++ b/tools/opt/Passes.cpp
@@ -0,0 +1,93 @@
+//===- Passes.cpp - Parsing, selection, and running of passes -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This file provides the infrastructure to parse and build a custom pass
+/// manager based on a commandline flag. It also provides helpers to aid in
+/// analyzing, debugging, and testing pass structures.
+///
+//===----------------------------------------------------------------------===//
+
+#include "Passes.h"
+#include "llvm/IR/PassManager.h"
+
+using namespace llvm;
+
+namespace {
+
+  /// \brief No-op module pass which does nothing.
+struct NoOpModulePass {
+  PreservedAnalyses run(Module *M) { return PreservedAnalyses::all(); }
+};
+
+} // End anonymous namespace.
+
+// FIXME: Factor all of the parsing logic into a .def file that we include
+// under different macros.
+static bool isModulePassName(StringRef Name) {
+  if (Name == "no-op-module") return true;
+
+  return false;
+}
+
+static bool parseModulePassName(ModulePassManager &MPM, StringRef Name) {
+  assert(isModulePassName(Name));
+  if (Name == "no-op-module") {
+    MPM.addPass(NoOpModulePass());
+    return true;
+  }
+  return false;
+}
+
+static bool parseModulePassPipeline(ModulePassManager &MPM,
+                                    StringRef &PipelineText) {
+  for (;;) {
+    // Parse nested pass managers by recursing.
+    if (PipelineText.startswith("module(")) {
+      PipelineText = PipelineText.substr(strlen("module("));
+      if (!parseModulePassPipeline(MPM, PipelineText))
+        return false;
+      assert(!PipelineText.empty() && PipelineText[0] == ')');
+      PipelineText = PipelineText.substr(1);
+    } else {
+      // Otherwise try to parse a pass name.
+      size_t End = PipelineText.find_first_of(",)");
+      if (!parseModulePassName(MPM, PipelineText.substr(0, End)))
+        return false;
+
+      PipelineText = PipelineText.substr(End);
+    }
+
+    if (PipelineText.empty() || PipelineText[0] == ')')
+      return true;
+
+    assert(PipelineText[0] == ',');
+    PipelineText = PipelineText.substr(1);
+  }
+}
+
+// Primary pass pipeline description parsing routine.
+// FIXME: Should this routine accept a TargetMachine or require the caller to
+// pre-populate the analysis managers with target-specific stuff?
+bool llvm::parsePassPipeline(ModulePassManager &MPM, StringRef PipelineText) {
+  // Look at the first entry to figure out which layer to start parsing at.
+  if (PipelineText.startswith("module("))
+    return parseModulePassPipeline(MPM, PipelineText);
+
+  // FIXME: Support parsing function pass manager nests.
+
+  // This isn't a direct pass manager name, look for the end of a pass name.
+  StringRef FirstName = PipelineText.substr(0, PipelineText.find_first_of(","));
+  if (isModulePassName(FirstName))
+    return parseModulePassPipeline(MPM, PipelineText);
+
+  // FIXME: Support parsing function pass names.
+
+  return false;
+}