[debuginfo][coro] Fix linkage name for clones of coro functions

So far, the `DW_AT_linkage_name` of the coroutine `resume`, `destroy`,
`cleanup` and `noalloc` functions were incorrectly set to the original
function name instead of the updated function names.

With this commit, we now update the `DW_AT_linkage_name` to the correct
name. This has multiple benefits:
1. it's easier for me (and other developers) to understand the output of
   `llvm-dwarf-dump` when coroutines are involved.
2. When hitting a breakpoint, both LLDB and GDB now tell you which clone
   of the function you are in. E.g., GDB now prints
   "Breakpoint 1.2, coro_func(int) [clone .resume] (v=43) at ..."
   instead of
   "Breakpoint 1.2, coro_func(int) (v=43) at ...".
3. GDB's `info line coro_func` command now allows you to distinguish the
   multiple different clones of the function.

In Swift, the linkage names of the clones were already updated. The
comment right above the relevant code in `CoroSplit.cpp` already hinted
that the linkage name should probably also be updated in C++. This
commit was added in commit 6ce76ff, and back then the
corresponding `DW_AT_specification` (i.e., `SP->getDeclaration()`) was
not updated, yet, which led to problems for C++. In the meantime, commit
ca1a5b3 added code to also update `SP->getDeclaration`, as such
there is no reason anymore to not update the linkage name for C++.

Note that most test cases used inconsistent function names for the LLVM
function vs. the DISubprogram linkage name. clang would never emit such
LLVM IR. This confused me initially, and hence I fixed it while updating
the test case.

Author: vogelsgesang

clang/lib/CodeGen/CGVTables.cpp

@@ -124,7 +124,7 @@ static void resolveTopLevelMetadata(llvm::Function *Fn,
   auto *DIS = Fn->getSubprogram();
   if (!DIS)
     return;
-  auto *NewDIS = DIS->replaceWithDistinct(DIS->clone());
+  auto *NewDIS = llvm::MDNode::replaceWithDistinct(DIS->clone());
   VMap.MD()[DIS].reset(NewDIS);
 
   // Find all llvm.dbg.declare intrinsics and resolve the DILocalVariable nodes

llvm/lib/Transforms/Coroutines/CoroSplit.cpp

@@ -912,29 +912,14 @@ void coro::BaseCloner::create() {
     assert(SP != OrigF.getSubprogram() && SP->isDistinct());
     updateScopeLine(ActiveSuspend, *SP);
 
-    // 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->getUnit() &&
-        SP->getUnit()->getSourceLanguage() == dwarf::DW_LANG_Swift) {
-      SP->replaceLinkageName(MDString::get(Context, NewF->getName()));
-      if (auto *Decl = SP->getDeclaration()) {
-        auto *NewDecl = DISubprogram::get(
-            Decl->getContext(), Decl->getScope(), Decl->getName(),
-            NewF->getName(), Decl->getFile(), Decl->getLine(), Decl->getType(),
-            Decl->getScopeLine(), Decl->getContainingType(),
-            Decl->getVirtualIndex(), Decl->getThisAdjustment(),
-            Decl->getFlags(), Decl->getSPFlags(), Decl->getUnit(),
-            Decl->getTemplateParams(), nullptr, Decl->getRetainedNodes(),
-            Decl->getThrownTypes(), Decl->getAnnotations(),
-            Decl->getTargetFuncName());
-        SP->replaceDeclaration(NewDecl);
-      }
+    // Update the linkage name and the functaion name to reflect the modified
+    // name.
+    MDString *NewLinkageName = MDString::get(Context, NewF->getName());
+    SP->replaceLinkageName(NewLinkageName);
+    if (DISubprogram *Decl = SP->getDeclaration()) {
+      TempDISubprogram NewDecl = Decl->clone();
+      NewDecl->replaceLinkageName(NewLinkageName);
+      SP->replaceDeclaration(MDNode::replaceWithUniqued(std::move(NewDecl)));
     }
   }
 

llvm/test/Transforms/Coroutines/coro-debug-dbg.values-not_used_in_frame.ll

@@ -2,18 +2,18 @@
 ; RUN: opt < %s -passes='module(coro-early),cgscc(coro-split,coro-split)' -S | FileCheck %s
 ;
 ; This file is based on coro-debug-frame-variable.ll.
-; CHECK:  define internal fastcc void @f.resume(ptr noundef nonnull align 16 dereferenceable(80) %begin) !dbg ![[RESUME_FN_DBG_NUM:[0-9]+]]
+; CHECK:  define internal fastcc void @_Z3foov.resume(ptr noundef nonnull align 16 dereferenceable(80) %begin) !dbg ![[RESUME_FN_DBG_NUM:[0-9]+]]
 ; CHECK:       await.ready:
 ; CHECK:         #dbg_value(i32 poison, ![[IVAR_RESUME:[0-9]+]], !DIExpression(
 ; CHECK:         #dbg_value(i32 poison, ![[JVAR_RESUME:[0-9]+]], !DIExpression(
 ;
-; CHECK: ![[RESUME_FN_DBG_NUM]] = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov"
+; CHECK: ![[RESUME_FN_DBG_NUM]] = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov.resume"
 ; CHECK: ![[IVAR_RESUME]] = !DILocalVariable(name: "i"
 ; CHECK: ![[JVAR_RESUME]] = !DILocalVariable(name: "j"
 
 source_filename = "../llvm/test/Transforms/Coroutines/coro-debug-dbg.values-O2.ll"
 
-define void @f(i32 %i, i32 %j) presplitcoroutine !dbg !8 {
+define void @_Z3foov(i32 %i, i32 %j) presplitcoroutine !dbg !8 {
 entry:
   %__promise = alloca i8, align 8
   %x = alloca [10 x i32], align 16

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

@@ -2,7 +2,7 @@
 ; RUN: opt < %s -passes='module(coro-early),cgscc(coro-split,coro-split)' -S | FileCheck %s
 ;
 ; This file is based on coro-debug-frame-variable.ll.
-; CHECK-LABEL: define void @f(
+; CHECK-LABEL: define void @_Z3foov(
 ; CHECK:       %[[frame:.*]] = call {{.*}} @llvm.coro.begin
 ; CHECK:       #dbg_value(ptr %[[frame]]
 ; CHECK-SAME:    !DIExpression(DW_OP_plus_uconst, [[OffsetX:[0-9]*]]),
@@ -20,7 +20,7 @@
 ; CHECK:       #dbg_value(ptr %[[frame]]
 ; CHECK-SAME:    !DIExpression(DW_OP_plus_uconst, [[OffsetJ:[0-9]*]], DW_OP_deref),
 
-; CHECK-LABEL: void @f.resume(
+; CHECK-LABEL: void @_Z3foov.resume(
 ; CHECK-SAME:                 ptr {{.*}} %[[frame:.*]])
 ; CHECK-SAME:  !dbg ![[RESUME_FN_DBG_NUM:[0-9]+]]
 ; CHECK:         %[[frame_alloca:.*]] = alloca ptr
@@ -37,7 +37,7 @@
 ; CHECK:         #dbg_value(ptr %[[frame_alloca]], ![[JVAR_RESUME:[0-9]+]],
 ; CHECK-SAME:        !DIExpression(DW_OP_deref, DW_OP_plus_uconst, [[OffsetJ]], DW_OP_deref)
 ;
-; CHECK: ![[RESUME_FN_DBG_NUM]] = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov"
+; CHECK: ![[RESUME_FN_DBG_NUM]] = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov.resume"
 ; CHECK: ![[FRAME_DI_NUM]] = !DILocalVariable(name: "__coro_frame"
 ; CHECK: ![[IVAR_RESUME]] = !DILocalVariable(name: "i"
 ; CHECK: ![[XVAR_RESUME]] = !DILocalVariable(name: "x"
@@ -46,7 +46,7 @@
 
 declare void @consume(i32)
 
-define void @f(i32 %i, i32 %j) presplitcoroutine !dbg !8 {
+define void @_Z3foov(i32 %i, i32 %j) presplitcoroutine !dbg !8 {
 entry:
   %__promise = alloca i8, align 8
   %x = alloca [10 x i32], align 16
@@ -257,4 +257,4 @@ attributes #4 = { argmemonly nofree nosync nounwind willreturn writeonly }
 !21 = !DILocation(line: 43, column: 3, scope: !7)
 !22 = !DILocation(line: 43, column: 8, scope: !7)
 !23 = !DILocalVariable(name: "produced", scope: !7, file: !1, line:24, type: !10)
-!30 = distinct !DIAssignID()
+!30 = distinct !DIAssignID()

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

@@ -23,11 +23,11 @@
 ;
 ; The CHECKs verify that dbg.declare intrinsics are created for the coroutine
 ; funclet 'f.resume', and that they reference the address of the variables on
-; the coroutine frame. The debug locations for the original function 'f' are
+; the coroutine frame. The debug locations for the original function 'foo' are
 ; static (!11 and !13), whereas the coroutine funclet will have its own new
 ; ones with identical line and column numbers.
 ;
-; CHECK-LABEL: define void @f() {{.*}} {
+; CHECK-LABEL: define void @_Z3foov() {{.*}} {
 ; CHECK:       entry:
 ; CHECK:         %j = alloca i32, align 4
 ; CHECK:         #dbg_declare(ptr %j, ![[JVAR:[0-9]+]], !DIExpression(), ![[JDBGLOC:[0-9]+]]
@@ -36,7 +36,7 @@
 ; CHECK:         #dbg_declare(ptr %[[MEMORY]], ![[IVAR:[0-9]+]], !DIExpression(DW_OP_plus_uconst, 20), ![[IDBGLOC]]
 ; CHECK:       await.ready:
 ;
-; CHECK-LABEL: define internal fastcc void @f.resume({{.*}}) {{.*}} {
+; CHECK-LABEL: define internal fastcc void @_Z3foov.resume({{.*}}) {{.*}} {
 ; CHECK:       entry.resume:
 ; CHECK-NEXT:    %[[DBG_PTR:.*]] = alloca ptr
 ; CHECK-NEXT:    #dbg_declare(ptr %[[DBG_PTR]], ![[XVAR_RESUME:[0-9]+]],   !DIExpression(DW_OP_deref, DW_OP_plus_uconst, 32),
@@ -58,13 +58,13 @@
 ; CHECK-DAG: ![[JDBGLOC]] = !DILocation(line: 32, column: 7, scope: ![[BLK_SCOPE]])
 
 ; CHECK-DAG: ![[XVAR_RESUME]] = !DILocalVariable(name: "x"
-; CHECK-DAG: ![[RESUME_PROG_SCOPE:[0-9]+]] = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov"
+; CHECK-DAG: ![[RESUME_PROG_SCOPE:[0-9]+]] = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov.resume"
 ; CHECK-DAG: ![[IDBGLOC_RESUME]] = !DILocation(line: 24, column: 7, scope: ![[RESUME_BLK_SCOPE:[0-9]+]])
 ; CHECK-DAG: ![[RESUME_BLK_SCOPE]] = distinct !DILexicalBlock(scope: ![[RESUME_PROG_SCOPE]], file: !1, line: 23, column: 12)
 ; CHECK-DAG: ![[IVAR_RESUME]] = !DILocalVariable(name: "i"
 ; CHECK-DAG: ![[JVAR_RESUME]] = !DILocalVariable(name: "j"
 ; CHECK-DAG: ![[JDBGLOC_RESUME]] = !DILocation(line: 32, column: 7, scope: ![[RESUME_BLK_SCOPE]])
-define void @f() presplitcoroutine !dbg !8 {
+define void @_Z3foov() presplitcoroutine !dbg !8 {
 entry:
   %__promise = alloca i8, align 8
   %i = alloca i32, align 4

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

@@ -6,12 +6,12 @@ target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 ; Function Attrs: noinline nounwind
-define ptr @f(i32 %x) #0 personality i32 0 !dbg !6 {
+define ptr @flink(i32 %x) #0 personality i32 0 !dbg !6 {
 entry:
   %x.addr = alloca i32, align 4
   %coro_hdl = alloca ptr, align 8
   store i32 %x, ptr %x.addr, align 4
-  %0 = call token @llvm.coro.id(i32 0, ptr null, ptr @f, ptr null), !dbg !16
+  %0 = call token @llvm.coro.id(i32 0, ptr null, ptr @flink, ptr null), !dbg !16
   %1 = call i64 @llvm.coro.size.i64(), !dbg !16
   %call = call ptr @malloc(i64 %1), !dbg !16
   %2 = call ptr @llvm.coro.begin(token %0, ptr %call) #7, !dbg !16
@@ -170,8 +170,8 @@ attributes #7 = { noduplicate }
 !31 = !DILocalVariable(name: "allocated", scope: !6, file: !7, line: 55, type: !11)
 !32 = !DILocalVariable(name: "inline_asm", scope: !6, file: !7, line: 55, type: !11)
 
-; CHECK: define ptr @f(i32 %x) #0 personality i32 0 !dbg ![[ORIG:[0-9]+]]
-; CHECK: define internal fastcc void @f.resume(ptr noundef nonnull align 8 dereferenceable(40) %0) #0 personality i32 0 !dbg ![[RESUME:[0-9]+]]
+; CHECK: define ptr @flink(i32 %x) #0 personality i32 0 !dbg ![[ORIG:[0-9]+]]
+; CHECK: define internal fastcc void @flink.resume(ptr noundef nonnull align 8 dereferenceable(40) %0) #0 personality i32 0 !dbg ![[RESUME:[0-9]+]]
 ; CHECK: entry.resume:
 ; CHECK: %[[DBG_PTR:.*]] = alloca ptr
 ; CHECK: #dbg_declare(ptr %[[DBG_PTR]], ![[RESUME_COROHDL:[0-9]+]], !DIExpression(DW_OP_deref, DW_OP_plus_uconst,
@@ -194,18 +194,18 @@ attributes #7 = { noduplicate }
 ; CHECK: [[DEFAULT_DEST]]:
 ; CHECK-NOT: {{.*}}:
 ; CHECK: #dbg_value(i32 %[[CALLBR_RES]]
-; CHECK: define internal fastcc void @f.destroy(ptr noundef nonnull align 8 dereferenceable(40) %0) #0 personality i32 0 !dbg ![[DESTROY:[0-9]+]]
-; CHECK: define internal fastcc void @f.cleanup(ptr noundef nonnull align 8 dereferenceable(40) %0) #0 personality i32 0 !dbg ![[CLEANUP:[0-9]+]]
+; CHECK: define internal fastcc void @flink.destroy(ptr noundef nonnull align 8 dereferenceable(40) %0) #0 personality i32 0 !dbg ![[DESTROY:[0-9]+]]
+; CHECK: define internal fastcc void @flink.cleanup(ptr noundef nonnull align 8 dereferenceable(40) %0) #0 personality i32 0 !dbg ![[CLEANUP:[0-9]+]]
 
 ; CHECK: ![[ORIG]] = distinct !DISubprogram(name: "f", linkageName: "flink"
 
-; CHECK: ![[RESUME]] = distinct !DISubprogram(name: "f", linkageName: "flink"
+; CHECK: ![[RESUME]] = distinct !DISubprogram(name: "f", linkageName: "flink.resume"
 ; CHECK: ![[RESUME_COROHDL]] = !DILocalVariable(name: "coro_hdl", scope: ![[RESUME]]
 ; CHECK: ![[RESUME_X]] = !DILocalVariable(name: "x", arg: 1, scope: ![[RESUME]]
 ; CHECK: ![[RESUME_CONST]] = !DILocalVariable(name: "direct_const", scope: ![[RESUME]]
 ; CHECK: ![[RESUME_DIRECT]] = !DILocalVariable(name: "direct_mem", scope: ![[RESUME]]
 ; CHECK: ![[RESUME_DIRECT_VALUE]] = !DILocalVariable(name: "direct_value", scope: ![[RESUME]]
 
-; CHECK: ![[DESTROY]] = distinct !DISubprogram(name: "f", linkageName: "flink"
+; CHECK: ![[DESTROY]] = distinct !DISubprogram(name: "f", linkageName: "flink.destroy"
 
-; CHECK: ![[CLEANUP]] = distinct !DISubprogram(name: "f", linkageName: "flink"
+; CHECK: ![[CLEANUP]] = distinct !DISubprogram(name: "f", linkageName: "flink.cleanup"