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, 0 insertions, 8 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
index 3b204b7..21ef320 100644
--- a/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
@@ -258,7 +258,6 @@ class DataFlowSanitizer : public ModulePass {
   DFSanABIList ABIList;
   DenseMap<Value *, Function *> UnwrappedFnMap;
   AttributeSet ReadOnlyNoneAttrs;
-  DenseMap<const Function *, DISubprogram *> FunctionDIs;
 
   Value *getShadowAddress(Value *Addr, Instruction *Pos);
   bool isInstrumented(const Function *F);
@@ -610,8 +609,6 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
   if (ABIList.isIn(M, "skip"))
     return false;
 
-  FunctionDIs = makeSubprogramMap(M);
-
   if (!GetArgTLSPtr) {
     Type *ArgTLSTy = ArrayType::get(ShadowTy, 64);
     ArgTLS = Mod->getOrInsertGlobal("__dfsan_arg_tls", ArgTLSTy);
@@ -768,11 +765,6 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
           ConstantExpr::getBitCast(NewF, PointerType::getUnqual(FT));
       F.replaceAllUsesWith(WrappedFnCst);
 
-      // Patch the pointer to LLVM function in debug info descriptor.
-      auto DI = FunctionDIs.find(&F);
-      if (DI != FunctionDIs.end())
-        DI->second->replaceFunction(&F);
-
       UnwrappedFnMap[WrappedFnCst] = &F;
       *i = NewF;