[Coroutines] Part15b: Fix dbg information handling in coro-split.

Summary:
Without the fix, if there was a function inlined into the coroutine with debug information, CloneFunctionInto(NewF, &F, VMap, /*ModuleLevelChanges=*/true, Returns); would duplicate all of the debug information including the DICompileUnit.

We know use VMap to indicate that debug metadata for a File, Unit and FunctionType should not be duplicated when we creating clones that will become f.resume, f.destroy and f.cleanup.

Reviewers: majnemer

Subscribers: mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D24417

llvm-svn: 282899

2 files changed, 13 insertions, 6 deletions

diff --git a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
index f6e0499a501..2b4e725fd0e 100644
--- a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
@@ -27,6 +27,7 @@
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/circular_raw_ostream.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
 
 using namespace llvm;
 
@@ -637,6 +638,10 @@ static void splitAround(Instruction *I, const Twine &Name) {
 }
 
 void coro::buildCoroutineFrame(Function &F, Shape &Shape) {
+  // Lower coro.dbg.declare to coro.dbg.value, since we are going to rewrite
+  // access to local variables.
+  LowerDbgDeclare(F);
+
   Shape.PromiseAlloca = Shape.CoroBegin->getId()->getPromise();
   if (Shape.PromiseAlloca) {
     Shape.CoroBegin->getId()->clearPromise();
diff --git a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
index 7233e5301b1..77c4be88a4e 100644
--- a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
@@ -200,14 +200,16 @@ static Function *createClone(Function &F, Twine Suffix, coro::Shape &Shape,
 
   SmallVector<ReturnInst *, 4> Returns;
 
+  if (DISubprogram *SP = F.getSubprogram()) {
+    // If we have debug info, add mapping for the metadata nodes that should not
+    // be cloned by CloneFunctionInfo.
+    auto &MD = VMap.MD();
+    MD[SP->getUnit()].reset(SP->getUnit());
+    MD[SP->getType()].reset(SP->getType());
+    MD[SP->getFile()].reset(SP->getFile());
+  }
   CloneFunctionInto(NewF, &F, VMap, /*ModuleLevelChanges=*/true, Returns);
 
-  // If we have debug info, update it. ModuleLevelChanges = true above, does
-  // the heavy lifting, we just need to repoint subprogram at the same
-  // DICompileUnit as the original function F.
-  if (DISubprogram *SP = F.getSubprogram())
-    NewF->getSubprogram()->replaceUnit(SP->getUnit());
-
   // Remove old returns.
   for (ReturnInst *Return : Returns)
     changeToUnreachable(Return, /*UseLLVMTrap=*/false);