[debuginfo][coro] Fix linkage name for clones of coro functions #141889

vogelsgesang · 2025-05-29T02:40:42Z

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:

it's easier for me (and other developers) to understand the output of llvm-dwarf-dump when coroutines are involved.
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 ...".
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.

llvmbot · 2025-05-29T02:41:16Z

@llvm/pr-subscribers-debuginfo
@llvm/pr-subscribers-clang-codegen
@llvm/pr-subscribers-clang

@llvm/pr-subscribers-coroutines

Author: Adrian Vogelsgesang (vogelsgesang)

Changes

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:

it's easier for me (and other developers) to understand the output of llvm-dwarf-dump when coroutines are involved.
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 ...".
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.

Full diff: https://github.com/llvm/llvm-project/pull/141889.diff

6 Files Affected:

(modified) clang/lib/CodeGen/CGVTables.cpp (+1-1)
(modified) llvm/lib/Transforms/Coroutines/CoroSplit.cpp (+7-23)
(modified) llvm/test/Transforms/Coroutines/coro-debug-dbg.values-not_used_in_frame.ll (+3-3)
(modified) llvm/test/Transforms/Coroutines/coro-debug-dbg.values.ll (+5-5)
(modified) llvm/test/Transforms/Coroutines/coro-debug-frame-variable.ll (+5-5)
(modified) llvm/test/Transforms/Coroutines/coro-debug.ll (+9-9)

diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index c7447273a42fa..2897ccdf88660 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/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
diff --git a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
index f9a6c70fedc2d..7ea0746c1886b 100644
--- a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
@@ -912,29 +912,13 @@ 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)));
     }
   }
 
diff --git a/llvm/test/Transforms/Coroutines/coro-debug-dbg.values-not_used_in_frame.ll b/llvm/test/Transforms/Coroutines/coro-debug-dbg.values-not_used_in_frame.ll
index 4da07c91eb486..deaec7b8d7f89 100644
--- a/llvm/test/Transforms/Coroutines/coro-debug-dbg.values-not_used_in_frame.ll
+++ b/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
diff --git a/llvm/test/Transforms/Coroutines/coro-debug-dbg.values.ll b/llvm/test/Transforms/Coroutines/coro-debug-dbg.values.ll
index 28592cc671062..5f7701c357ec3 100644
--- a/llvm/test/Transforms/Coroutines/coro-debug-dbg.values.ll
+++ b/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()
\ No newline at end of file
+!30 = distinct !DIAssignID()
diff --git a/llvm/test/Transforms/Coroutines/coro-debug-frame-variable.ll b/llvm/test/Transforms/Coroutines/coro-debug-frame-variable.ll
index a3c62b2dd12e1..125ec752c8345 100644
--- a/llvm/test/Transforms/Coroutines/coro-debug-frame-variable.ll
+++ b/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
diff --git a/llvm/test/Transforms/Coroutines/coro-debug.ll b/llvm/test/Transforms/Coroutines/coro-debug.ll
index 17a0b80c5b5e5..a220073248ba3 100644
--- a/llvm/test/Transforms/Coroutines/coro-debug.ll
+++ b/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"

llvmbot · 2025-05-29T02:41:16Z

@llvm/pr-subscribers-llvm-transforms

Author: Adrian Vogelsgesang (vogelsgesang)

Changes

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:

it's easier for me (and other developers) to understand the output of llvm-dwarf-dump when coroutines are involved.
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 ...".
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.

Full diff: https://github.com/llvm/llvm-project/pull/141889.diff

6 Files Affected:

(modified) clang/lib/CodeGen/CGVTables.cpp (+1-1)
(modified) llvm/lib/Transforms/Coroutines/CoroSplit.cpp (+7-23)
(modified) llvm/test/Transforms/Coroutines/coro-debug-dbg.values-not_used_in_frame.ll (+3-3)
(modified) llvm/test/Transforms/Coroutines/coro-debug-dbg.values.ll (+5-5)
(modified) llvm/test/Transforms/Coroutines/coro-debug-frame-variable.ll (+5-5)
(modified) llvm/test/Transforms/Coroutines/coro-debug.ll (+9-9)

diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index c7447273a42fa..2897ccdf88660 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/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
diff --git a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
index f9a6c70fedc2d..7ea0746c1886b 100644
--- a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
@@ -912,29 +912,13 @@ 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)));
     }
   }
 
diff --git a/llvm/test/Transforms/Coroutines/coro-debug-dbg.values-not_used_in_frame.ll b/llvm/test/Transforms/Coroutines/coro-debug-dbg.values-not_used_in_frame.ll
index 4da07c91eb486..deaec7b8d7f89 100644
--- a/llvm/test/Transforms/Coroutines/coro-debug-dbg.values-not_used_in_frame.ll
+++ b/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
diff --git a/llvm/test/Transforms/Coroutines/coro-debug-dbg.values.ll b/llvm/test/Transforms/Coroutines/coro-debug-dbg.values.ll
index 28592cc671062..5f7701c357ec3 100644
--- a/llvm/test/Transforms/Coroutines/coro-debug-dbg.values.ll
+++ b/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()
\ No newline at end of file
+!30 = distinct !DIAssignID()
diff --git a/llvm/test/Transforms/Coroutines/coro-debug-frame-variable.ll b/llvm/test/Transforms/Coroutines/coro-debug-frame-variable.ll
index a3c62b2dd12e1..125ec752c8345 100644
--- a/llvm/test/Transforms/Coroutines/coro-debug-frame-variable.ll
+++ b/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
diff --git a/llvm/test/Transforms/Coroutines/coro-debug.ll b/llvm/test/Transforms/Coroutines/coro-debug.ll
index 17a0b80c5b5e5..a220073248ba3 100644
--- a/llvm/test/Transforms/Coroutines/coro-debug.ll
+++ b/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"

vogelsgesang · 2025-05-29T02:42:48Z

CC @adrian-prantl @dianqk as authors of the two reference commits (6ce76ff, ca1a5b3) which I am building on top of

CC @hokein @ChuanqiXu9 since I know the two also worked on debuggability of coroutines before

github-actions · 2025-05-29T02:43:18Z

✅ With the latest revision this PR passed the C/C++ code formatter.

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.

dianqk · 2025-05-31T05:02:16Z

Sorry...
I probably can fix something; however, I am incapable of reviewing about debug info.

vogelsgesang requested a review from ChuanqiXu9 May 29, 2025 02:40

llvmbot added clang Clang issues not falling into any other category clang:codegen IR generation bugs: mangling, exceptions, etc. coroutines C++20 coroutines llvm:transforms labels May 29, 2025

vogelsgesang requested review from adrian-prantl and hokein May 29, 2025 02:43

vogelsgesang requested a review from dianqk May 29, 2025 02:43

vogelsgesang force-pushed the coro-supend-labels branch from 2aa7ea1 to 700c1c4 Compare May 29, 2025 02:45

vogelsgesang added the debuginfo label May 29, 2025

dianqk removed their request for review May 31, 2025 05:02

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

[debuginfo][coro] Fix linkage name for clones of coro functions #141889

[debuginfo][coro] Fix linkage name for clones of coro functions #141889

vogelsgesang commented May 29, 2025

Uh oh!

llvmbot commented May 29, 2025 •

edited

Loading

Uh oh!

llvmbot commented May 29, 2025

Uh oh!

vogelsgesang commented May 29, 2025

Uh oh!

github-actions bot commented May 29, 2025 •

edited

Loading

Uh oh!

dianqk commented May 31, 2025

Uh oh!

Uh oh!

[debuginfo][coro] Fix linkage name for clones of coro functions #141889

Are you sure you want to change the base?

[debuginfo][coro] Fix linkage name for clones of coro functions #141889

Conversation

vogelsgesang commented May 29, 2025

Uh oh!

llvmbot commented May 29, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

llvmbot commented May 29, 2025

Uh oh!

vogelsgesang commented May 29, 2025

Uh oh!

github-actions bot commented May 29, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

dianqk commented May 31, 2025

Uh oh!

Uh oh!

llvmbot commented May 29, 2025 •

edited

Loading

github-actions bot commented May 29, 2025 •

edited

Loading