Make it illegal for two Functions to point to the same DISubprogram

As recently discussed on llvm-dev [1], this patch makes it illegal for
two Functions to point to the same DISubprogram and updates
FunctionCloner to also clone the debug info of a function to conform
to the new requirement. To simplify the implementation it also factors
out the creation of inlineAt locations from the Inliner into a
general-purpose utility in DILocation.

[1] http://lists.llvm.org/pipermail/llvm-dev/2017-May/112661.html
<rdar://problem/31926379>

Differential Revision: https://reviews.llvm.org/D32975

This reapplies r302469 with a fix for a bot failure (reparentDebugInfo
now checks for the case the orig and new function are identical).

llvm-svn: 302576

1 files changed, 16 insertions, 0 deletions

diff --git a/llvm/include/llvm/IR/DebugLoc.h b/llvm/include/llvm/IR/DebugLoc.h
index 202be3da14d..aa74f361cda 100644
--- a/llvm/include/llvm/IR/DebugLoc.h
+++ b/llvm/include/llvm/IR/DebugLoc.h
@@ -80,6 +80,22 @@ namespace llvm {
     static DebugLoc get(unsigned Line, unsigned Col, const MDNode *Scope,
                         const MDNode *InlinedAt = nullptr);
 
+    enum { ReplaceLastInlinedAt = true };
+    /// Rebuild the entire inlined-at chain for this instruction so that the top of
+    /// the chain now is inlined-at the new call site.
+    /// \param   InlinedAt    The new outermost inlined-at in the chain.
+    /// \param   ReplaceLast  Replace the last location in the inlined-at chain.
+    static DebugLoc appendInlinedAt(DebugLoc DL, DILocation *InlinedAt,
+                                    LLVMContext &Ctx,
+                                    DenseMap<const MDNode *, MDNode *> &Cache,
+                                    bool ReplaceLast = false);
+
+    /// Reparent all debug locations referenced by \c I that belong to \c OrigSP
+    /// to become (possibly indirect) children of \c NewSP.
+    static void reparentDebugInfo(Instruction &I, DISubprogram *OrigSP,
+                                  DISubprogram *NewSP,
+                                  DenseMap<const MDNode *, MDNode *> &Cache);
+
     unsigned getLine() const;
     unsigned getCol() const;
     MDNode *getScope() const;