Merge pull request #2824 from adrian-prantl/linkage-name

Update the linkage name of coro-split functions in the debug info.

Author: adrian-prantl

llvm/include/llvm/IR/DebugInfoMetadata.h

@@ -2067,6 +2067,8 @@ class DISubprogram : public DILocalScope {
 
   StringRef getName() const { return getStringOperand(2); }
   StringRef getLinkageName() const { return getStringOperand(3); }
+  /// Only used by clients of CloneFunction, and only right after the cloning.
+  void replaceLinkageName(MDString *LN) { replaceOperandWith(3, LN); }
 
   DISubroutineType *getType() const {
     return cast_or_null<DISubroutineType>(getRawType());

llvm/lib/Transforms/Coroutines/CoroSplit.cpp

@@ -862,12 +862,26 @@ void CoroCloner::create() {
 
   CloneFunctionInto(NewF, &OrigF, VMap, /*ModuleLevelChanges=*/true, Returns);
 
-  // Adjust the scope line of the clone to the line number of the suspend point.
+  // For async functions / continuations, adjust the scope line of the
+  // clone to the line number of the suspend point. The scope line is
+  // associated with all pre-prologue instructions. This avoids a jump
+  // in the linetable from the function declaration to the suspend point.
   if (DISubprogram *SP = NewF->getSubprogram()) {
     assert(SP != OrigF.getSubprogram() && SP->isDistinct());
     if (ActiveSuspend)
       if (auto DL = ActiveSuspend->getDebugLoc())
         SP->setScopeLine(DL->getLine());
+    // Update the linkage name to reflect the modified symbol name. It
+    // is necessary to update the linkage name in Swift, since the
+    // mangling changes for resume functions. It might also be the
+    // right thing to do in C++, but due to a limitation in LLVM's
+    // AsmPrinter we can only do this if the function doesn't have an
+    // abstract specification, since the DWARF backend expects the
+    // abstract specification to contain the linkage name and asserts
+    // that they are identical.
+    if (!SP->getDeclaration() && SP->getUnit() &&
+        SP->getUnit()->getSourceLanguage() == dwarf::DW_LANG_Swift)
+      SP->replaceLinkageName(MDString::get(Context, NewF->getName()));
   }
 
   NewF->setLinkage(savedLinkage);

llvm/test/Transforms/Coroutines/coro-async.ll

@@ -544,7 +544,7 @@ declare void @llvm.coro.async.size.replace(i8*, i8*)
                             scope: !2, file: !3, line: 1, type: !4,
                             scopeLine: 1, spFlags: DISPFlagDefinition, unit: !2)
 ; CHECK: ![[SP2]] = distinct !DISubprogram(name: "my_async_function",
-; CHECK-SAME:                              linkageName: "my_async_function",
+; CHECK-SAME:                              linkageName: "my_async_function.resume.0",
 ; CHECK-SAME:                              scopeLine: 2
 !2 = distinct !DICompileUnit(language: DW_LANG_Swift, file: !3, emissionKind: FullDebug)
 !3 = !DIFile(filename: "/tmp/1.swift", directory: "/")

llvm/test/Transforms/Coroutines/coro-debug.ll

@@ -113,7 +113,7 @@ attributes #7 = { noduplicate }
 !3 = !{i32 2, !"Dwarf Version", i32 4}
 !4 = !{i32 2, !"Debug Info Version", i32 3}
 !5 = !{!"clang version 5.0.0"}
-!6 = distinct !DISubprogram(name: "f", linkageName: "flink", scope: !7, file: !7, line: 55, type: !8, isLocal: false, isDefinition: true, scopeLine: 55, flags: DIFlagPrototyped, isOptimized: false, unit: !0, retainedNodes: !2)
+!6 = distinct !DISubprogram(name: "f", linkageName: "flink", scope: !7, file: !7, line: 55, type: !8, isLocal: false, isDefinition: true, scopeLine: 55, flags: DIFlagPrototyped, isOptimized: false, unit: !0, retainedNodes: !2, declaration: !DISubprogram(name: "f", linkageName: "flink", scope: !7, file: !7, line: 55, type: !8, isLocal: false, isDefinition: false, flags: DIFlagPrototyped))
 !7 = !DIFile(filename: "simple-repro.c", directory: "C:\5CGitHub\5Cllvm\5Cbuild\5CDebug\5Cbin")
 !8 = !DISubroutineType(types: !9)
 !9 = !{!10, !11}