Until now all debug info MDNodes referred to a root MDNode, a compile unit. This simplified handling of these needs in dwarf writer. However, one side effect of this is that during link time optimization all these MDNodes are _not_ uniqued. In other words there will be N number of MDNodes describing "int", "char" and all other types, which would suddenly grow when each object file starts using libraries like STL.

MDNodes graph structure such that compiler unit keeps track of important MDNodes and update dwarf writer to process mdnodes top-down instead of bottom up.

llvm-svn: 137778

Author: Devang Patel

llvm/docs/SourceLevelDebugging.html

@@ -355,7 +355,7 @@ <h4>
              ;; (DW_TAG_file_type)
   metadata,  ;; Source file name
   metadata,  ;; Source file directory (includes trailing slash)
-  metadata   ;; Reference to compile unit where defined
+  metadata   ;; Unused
 }
 </pre>
 </div>
@@ -365,8 +365,7 @@ <h4>
    provide context for source line correspondence. </p>
 
 <p>Each input file is encoded as a separate file descriptor in LLVM debugging
-   information output. Each file descriptor would be defined using a 
-   compile unit. </p>
+   information output. </p>
 
 </div>
 
@@ -485,7 +484,7 @@ <h4>
 !4 = metadata !{
   i32,      ;; Tag = 36 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> 
             ;; (DW_TAG_base_type)
-  metadata, ;; Reference to context (typically a compile unit)
+  metadata, ;; Reference to context 
   metadata, ;; Name (may be "" for anonymous types)
   metadata, ;; Reference to file where defined (may be NULL)
   i32,      ;; Line number where defined (may be 0)
@@ -500,7 +499,7 @@ <h4>
 
 <p>These descriptors define primitive types used in the code. Example int, bool
    and float.  The context provides the scope of the type, which is usually the
-   top level.  Since basic types are not usually user defined the compile unit
+   top level.  Since basic types are not usually user defined the context
    and line number can be left as NULL and 0.  The size, alignment and offset
    are expressed in bits and can be 64 bit values.  The alignment is used to
    round the offset when embedded in a
@@ -585,7 +584,7 @@ <h4>
    the <a href="#format_derived_type">derived type</a>. </p>
 
 <p><a href="#format_derived_type">Derived type</a> location can be determined
-   from the compile unit and line number.  The size, alignment and offset are
+   from the context and line number.  The size, alignment and offset are
    expressed in bits and can be 64 bit values.  The alignment is used to round
    the offset when embedded in a <a href="#format_composite_type">composite
    type</a> (example to keep float doubles on 64 bit boundaries.) The offset is
@@ -675,7 +674,7 @@ <h4>
    the formal arguments to the subroutine.</p>
 
 <p><a href="#format_composite_type">Composite type</a> location can be
-   determined from the compile unit and line number.  The size, alignment and
+   determined from the context and line number.  The size, alignment and
    offset are expressed in bits and can be 64 bit values.  The alignment is used
    to round the offset when embedded in
    a <a href="#format_composite_type">composite type</a> (as an example, to keep
@@ -774,7 +773,7 @@ <h4>
    has no source correspondent.</p>
 
 <p>The context is either the subprogram or block where the variable is defined.
-   Name the source variable name.  Compile unit and line indicate where the
+   Name the source variable name.  Context and line indicate where the
    variable was defined. Type descriptor defines the declared type of the
    variable.</p>
 

llvm/include/llvm/Analysis/DIBuilder.h

@@ -48,9 +48,19 @@ namespace llvm {
     LLVMContext & VMContext;
     MDNode *TheCU;
 
+    MDNode *TempEnumTypes;
+    MDNode *TempRetainTypes;
+    MDNode *TempSubprograms;
+    MDNode *TempGVs;
+
     Function *DeclareFn;     // llvm.dbg.declare
     Function *ValueFn;       // llvm.dbg.value
 
+    SmallVector<Value *, 4> AllEnumTypes;
+    SmallVector<Value *, 4> AllRetainTypes;
+    SmallVector<Value *, 4> AllSubprograms;
+    SmallVector<Value *, 4> AllGVs;
+
     DIBuilder(const DIBuilder &);       // DO NOT IMPLEMENT
     void operator=(const DIBuilder &);  // DO NOT IMPLEMENT
 

llvm/include/llvm/Analysis/DebugInfo.h

@@ -182,6 +182,11 @@ namespace llvm {
     StringRef getFlags() const       { return getStringField(8);   }
     unsigned getRunTimeVersion() const { return getUnsignedField(9); }
 
+    DIArray getEnumTypes() const;
+    DIArray getRetainedTypes() const;
+    DIArray getSubprograms() const;
+    DIArray getGlobalVariables() const;
+
     /// Verify - Verify that a compile unit is well formed.
     bool Verify() const;
 
@@ -201,7 +206,10 @@ namespace llvm {
     }
     StringRef getFilename() const  { return getStringField(1);   }
     StringRef getDirectory() const { return getStringField(2);   }
-    DICompileUnit getCompileUnit() const{ return getFieldAs<DICompileUnit>(3); }
+    DICompileUnit getCompileUnit() const{ 
+      assert (getVersion() <= LLVMDebugVersion10  && "Invalid CompileUnit!");
+      return getFieldAs<DICompileUnit>(3); 
+    }
   };
 
   /// DIEnumerator - A wrapper for an enumerator (e.g. X and Y in 'enum {X,Y}').
@@ -237,6 +245,7 @@ namespace llvm {
     DIScope getContext() const          { return getFieldAs<DIScope>(1); }
     StringRef getName() const           { return getStringField(2);     }
     DICompileUnit getCompileUnit() const{ 
+      assert (getVersion() <= LLVMDebugVersion10 && "Invalid getCompileUnit!");
      if (getVersion() == llvm::LLVMDebugVersion7)
        return getFieldAs<DICompileUnit>(3);
 
@@ -450,6 +459,7 @@ namespace llvm {
     StringRef getDisplayName() const  { return getStringField(4); }
     StringRef getLinkageName() const  { return getStringField(5); }
     DICompileUnit getCompileUnit() const{ 
+      assert (getVersion() <= LLVMDebugVersion10 && "Invalid getCompileUnit!");
       if (getVersion() == llvm::LLVMDebugVersion7)
         return getFieldAs<DICompileUnit>(6);
 
@@ -560,6 +570,7 @@ namespace llvm {
     StringRef getDisplayName() const  { return getStringField(4); }
     StringRef getLinkageName() const  { return getStringField(5); }
     DICompileUnit getCompileUnit() const{ 
+      assert (getVersion() <= LLVMDebugVersion10 && "Invalid getCompileUnit!");
       if (getVersion() == llvm::LLVMDebugVersion7)
         return getFieldAs<DICompileUnit>(6);
 
@@ -595,6 +606,7 @@ namespace llvm {
     DIScope getContext() const          { return getFieldAs<DIScope>(1); }
     StringRef getName() const           { return getStringField(2);     }
     DICompileUnit getCompileUnit() const{ 
+      assert (getVersion() <= LLVMDebugVersion10 && "Invalid getCompileUnit!");
       if (getVersion() == llvm::LLVMDebugVersion7)
         return getFieldAs<DICompileUnit>(3);
 
@@ -687,6 +699,7 @@ namespace llvm {
       return getFieldAs<DIFile>(3).getFilename();
     }
     DICompileUnit getCompileUnit() const{ 
+      assert (getVersion() <= LLVMDebugVersion10 && "Invalid getCompileUnit!");
       if (getVersion() == llvm::LLVMDebugVersion7)
         return getFieldAs<DICompileUnit>(3);