DI: Reverse direction of subprogram -> function edge.

Previously, subprograms contained a metadata reference to the function they
described. Because most clients need to get or set a subprogram for a given
function rather than the other way around, this created unneeded inefficiency.

For example, many passes needed to call the function llvm::makeSubprogramMap()
to build a mapping from functions to subprograms, and the IR linker needed to
fix up function references in a way that caused quadratic complexity in the IR
linking phase of LTO.

This change reverses the direction of the edge by storing the subprogram as
function-level metadata and removing DISubprogram's function field.

Since this is an IR change, a bitcode upgrade has been provided.

Fixes PR23367. An upgrade script for textual IR for out-of-tree clients is
attached to the PR.

Differential Revision: http://reviews.llvm.org/D14265

llvm-svn: 252219

1 files changed, 25 insertions, 32 deletions

diff --git a/llvm/lib/IR/DIBuilder.cpp b/llvm/lib/IR/DIBuilder.cpp
index def72d6cf6e..7fc0652bf65 100644
--- a/llvm/lib/IR/DIBuilder.cpp
+++ b/llvm/lib/IR/DIBuilder.cpp
@@ -659,19 +659,17 @@ DIExpression *DIBuilder::createBitPieceExpression(unsigned OffsetInBytes,
   return DIExpression::get(VMContext, Addr);
 }
 
-DISubprogram *DIBuilder::createFunction(DIScopeRef Context, StringRef Name,
-                                        StringRef LinkageName, DIFile *File,
-                                        unsigned LineNo, DISubroutineType *Ty,
-                                        bool isLocalToUnit, bool isDefinition,
-                                        unsigned ScopeLine, unsigned Flags,
-                                        bool isOptimized, Function *Fn,
-                                        MDNode *TParams, MDNode *Decl) {
+DISubprogram *DIBuilder::createFunction(
+    DIScopeRef Context, StringRef Name, StringRef LinkageName, DIFile *File,
+    unsigned LineNo, DISubroutineType *Ty, bool isLocalToUnit,
+    bool isDefinition, unsigned ScopeLine, unsigned Flags, bool isOptimized,
+    DITemplateParameterArray TParams, DISubprogram *Decl) {
   // dragonegg does not generate identifier for types, so using an empty map
   // to resolve the context should be fine.
   DITypeIdentifierMap EmptyMap;
   return createFunction(Context.resolve(EmptyMap), Name, LinkageName, File,
                         LineNo, Ty, isLocalToUnit, isDefinition, ScopeLine,
-                        Flags, isOptimized, Fn, TParams, Decl);
+                        Flags, isOptimized, TParams, Decl);
 }
 
 template <class... Ts>
@@ -681,20 +679,17 @@ static DISubprogram *getSubprogram(bool IsDistinct, Ts &&... Args) {
   return DISubprogram::get(std::forward<Ts>(Args)...);
 }
 
-DISubprogram *DIBuilder::createFunction(DIScope *Context, StringRef Name,
-                                        StringRef LinkageName, DIFile *File,
-                                        unsigned LineNo, DISubroutineType *Ty,
-                                        bool isLocalToUnit, bool isDefinition,
-                                        unsigned ScopeLine, unsigned Flags,
-                                        bool isOptimized, Function *Fn,
-                                        MDNode *TParams, MDNode *Decl) {
-  auto *Node = getSubprogram(/* IsDistinct = */ isDefinition, VMContext,
-                             DIScopeRef::get(getNonCompileUnitScope(Context)),
-                             Name, LinkageName, File, LineNo, Ty, isLocalToUnit,
-                             isDefinition, ScopeLine, nullptr, 0, 0, Flags,
-                             isOptimized, Fn, cast_or_null<MDTuple>(TParams),
-                             cast_or_null<DISubprogram>(Decl),
-                             MDTuple::getTemporary(VMContext, None).release());
+DISubprogram *DIBuilder::createFunction(
+    DIScope *Context, StringRef Name, StringRef LinkageName, DIFile *File,
+    unsigned LineNo, DISubroutineType *Ty, bool isLocalToUnit,
+    bool isDefinition, unsigned ScopeLine, unsigned Flags, bool isOptimized,
+    DITemplateParameterArray TParams, DISubprogram *Decl) {
+  auto *Node =
+      getSubprogram(/* IsDistinct = */ isDefinition, VMContext,
+                    DIScopeRef::get(getNonCompileUnitScope(Context)), Name,
+                    LinkageName, File, LineNo, Ty, isLocalToUnit, isDefinition,
+                    ScopeLine, nullptr, 0, 0, Flags, isOptimized, TParams, Decl,
+                    MDTuple::getTemporary(VMContext, None).release());
 
   if (isDefinition)
     AllSubprograms.push_back(Node);
@@ -706,12 +701,11 @@ DISubprogram *DIBuilder::createTempFunctionFwdDecl(
     DIScope *Context, StringRef Name, StringRef LinkageName, DIFile *File,
     unsigned LineNo, DISubroutineType *Ty, bool isLocalToUnit,
     bool isDefinition, unsigned ScopeLine, unsigned Flags, bool isOptimized,
-    Function *Fn, MDNode *TParams, MDNode *Decl) {
+    DITemplateParameterArray TParams, DISubprogram *Decl) {
   return DISubprogram::getTemporary(
              VMContext, DIScopeRef::get(getNonCompileUnitScope(Context)), Name,
              LinkageName, File, LineNo, Ty, isLocalToUnit, isDefinition,
-             ScopeLine, nullptr, 0, 0, Flags, isOptimized, Fn,
-             cast_or_null<MDTuple>(TParams), cast_or_null<DISubprogram>(Decl),
+             ScopeLine, nullptr, 0, 0, Flags, isOptimized, TParams, Decl,
              nullptr)
       .release();
 }
@@ -721,17 +715,16 @@ DIBuilder::createMethod(DIScope *Context, StringRef Name, StringRef LinkageName,
                         DIFile *F, unsigned LineNo, DISubroutineType *Ty,
                         bool isLocalToUnit, bool isDefinition, unsigned VK,
                         unsigned VIndex, DIType *VTableHolder, unsigned Flags,
-                        bool isOptimized, Function *Fn, MDNode *TParam) {
+                        bool isOptimized, DITemplateParameterArray TParams) {
   assert(getNonCompileUnitScope(Context) &&
          "Methods should have both a Context and a context that isn't "
          "the compile unit.");
   // FIXME: Do we want to use different scope/lines?
-  auto *SP = getSubprogram(/* IsDistinct = */ isDefinition, VMContext,
-                           DIScopeRef::get(cast<DIScope>(Context)), Name,
-                           LinkageName, F, LineNo, Ty, isLocalToUnit,
-                           isDefinition, LineNo, DITypeRef::get(VTableHolder),
-                           VK, VIndex, Flags, isOptimized, Fn,
-                           cast_or_null<MDTuple>(TParam), nullptr, nullptr);
+  auto *SP = getSubprogram(
+      /* IsDistinct = */ isDefinition, VMContext,
+      DIScopeRef::get(cast<DIScope>(Context)), Name, LinkageName, F, LineNo, Ty,
+      isLocalToUnit, isDefinition, LineNo, DITypeRef::get(VTableHolder), VK,
+      VIndex, Flags, isOptimized, TParams, nullptr, nullptr);
 
   if (isDefinition)
     AllSubprograms.push_back(SP);