From d0a4db76324e40e38a23429c07eda76f9f26a153 Mon Sep 17 00:00:00 2001
From: Michael Ilseman <milseman@apple.com>
Date: Thu, 6 Oct 2016 17:58:38 +0000
Subject: Add -strip-nonlinetable-debuginfo capability

This adds a new function to DebugInfo.cpp that takes an llvm::Module
as input and removes all debug info metadata that is not directly
needed for line tables, thus effectively stripping all type and
variable information from the module.

The primary motivation for this feature was the bitcode work flow
(cf. http://lists.llvm.org/pipermail/llvm-dev/2016-June/100643.html
for more background). This is not wired up yet, but will be in
subsequent patches.  For testing, the new functionality is exposed to
opt with a -strip-nonlinetable-debuginfo option.

The secondary use-case (and one that works right now!) is as a
reduction pass in bugpoint. I added two new bugpoint options
(-disable-strip-debuginfo and -disable-strip-debug-types) to control
the new features. By default it will first attempt to remove all debug
information, then only the type info, and then proceed to hack at any
remaining MDNodes.

llvm-svn: 283473
---
 .../Utils/StripNonLineTableDebugInfo.cpp           | 42 ++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 llvm/lib/Transforms/Utils/StripNonLineTableDebugInfo.cpp

(limited to 'llvm/lib/Transforms/Utils/StripNonLineTableDebugInfo.cpp')

diff --git a/llvm/lib/Transforms/Utils/StripNonLineTableDebugInfo.cpp b/llvm/lib/Transforms/Utils/StripNonLineTableDebugInfo.cpp
new file mode 100644
index 0000000..66dbf33
--- /dev/null
+++ b/llvm/lib/Transforms/Utils/StripNonLineTableDebugInfo.cpp
@@ -0,0 +1,42 @@
+//===- StripNonLineTableDebugInfo.cpp -- Strip parts of Debug Info --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/IPO.h"
+#include "llvm/IR/DebugInfo.h"
+#include "llvm/Pass.h"
+using namespace llvm;
+
+namespace {
+
+/// This pass strips all debug info that is not related line tables.
+/// The result will be the same as if the program where compiled with
+/// -gline-tables-only.
+struct StripNonLineTableDebugInfo : public ModulePass {
+  static char ID; // Pass identification, replacement for typeid
+  StripNonLineTableDebugInfo() : ModulePass(ID) {
+    initializeStripNonLineTableDebugInfoPass(*PassRegistry::getPassRegistry());
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesAll();
+  }
+
+  bool runOnModule(Module &M) override {
+    return llvm::stripNonLineTableDebugInfo(M);
+  }
+};
+}
+
+char StripNonLineTableDebugInfo::ID = 0;
+INITIALIZE_PASS(StripNonLineTableDebugInfo, "strip-nonlinetable-debuginfo",
+                "Strip all debug info except linetables", false, false)
+
+ModulePass *llvm::createStripNonLineTableDebugInfoPass() {
+  return new StripNonLineTableDebugInfo();
+}
-- 
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