[AIX]Generate debug info for static init related functions

[Xiangling_L]

Summary

Set the debug location for static init related functions(dtor and finalize) so we can generate valid debug info on AIX by invoking -g with clang or -debug-info-kind=limited with clang_cc1.

This also works for any other future targets who may use sinit and sterm functions for static initialization, where a direct call to dtor will be generated within finalize function body.

This patch also aims at validating that the debug info generated is correct for AIX sinit related functions.

[dblaikie]

clang/lib/CodeGen/CGDeclCXX.cpp

248–251

Any ideas why this is only showing up for AIX & not other targets, given this code looks to be generic, not AIX-specific?

clang/test/CodeGenCXX/aix-static-init-debug-info.cpp

10–20

This could probably be simplified to:

struct X {
  X();
  ~X();
};

This would still produce a global ctor and dtor without the superfluous variable, etc.

[hubert.reinterpretcast]

clang/lib/CodeGen/CGDeclCXX.cpp

248–251

Yes, because the AIX implementation generates a direct call to the stub function on the finalization path when it finds that a stub was still registered with atexit.

That would explain why other platforms to not encounter this message:

inlinable function call in a function with debug info must have a !dbg location

[dblaikie]

clang/lib/CodeGen/CGDeclCXX.cpp

248–251

Ah, fair enough - thanks for the context!

clang/test/CodeGenCXX/aix-static-init-debug-info.cpp

10–20

Could you simplify the test a bit like this? If it's only about the global /dtor/, perhaps omit the ctor in X too.

& which exact call in the test is the important one? Perhaps just test that?

[Xiangling_L]

Simplified the testcase;

[dblaikie]

Looks good - thanks!

clang/lib/CodeGen/CGDeclCXX.cpp

llvm::Function *CodeGenFunction::createAtExitStub(const VarDecl &VD,
   }
 
   const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction();
   llvm::Function *fn = CGM.CreateGlobalInitOrCleanUpFunction(
       ty, FnName.str(), FI, VD.getLocation());
 
   CodeGenFunction CGF(CGM);
 
   CGF.StartFunction(GlobalDecl(&VD, DynamicInitKind::AtExit),
-                    CGM.getContext().VoidTy, fn, FI, FunctionArgList());
+                    CGM.getContext().VoidTy, fn, FI, FunctionArgList(),
+                    VD.getLocation(), VD.getInit()->getExprLoc());
 
   llvm::CallInst *call = CGF.Builder.CreateCall(dtor, addr);
 
   // Make sure the call and the callee agree on calling convention.
   if (auto *dtorFn = dyn_cast<llvm::Function>(
           dtor.getCallee()->stripPointerCastsAndAliases()))
     call->setCallingConv(dtorFn->getCallingConv());
 
   CGF.FinishFunction();

clang/lib/CodeGen/ItaniumCXXABI.cpp

void XLCXXABI::emitCXXStermFinalizer(const VarDecl &D, llvm::Function *dtorStub,
   // Create the finalization action associated with a variable.
   const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction();
   llvm::Function *StermFinalizer = CGM.CreateGlobalInitOrCleanUpFunction(
       FTy, FnName.str(), FI, D.getLocation());
 
   CodeGenFunction CGF(CGM);
 
   CGF.StartFunction(GlobalDecl(), CGM.getContext().VoidTy, StermFinalizer, FI,
-                    FunctionArgList());
+                    FunctionArgList(), D.getLocation(),
+                    D.getInit()->getExprLoc());
 
   // The unatexit subroutine unregisters __dtor functions that were previously
   // registered by the atexit subroutine. If the referenced function is found,
   // the unatexit returns a value of 0, meaning that the cleanup is still
   // pending (and we should call the __dtor function).
   llvm::Value *V = CGF.unregisterGlobalDtorWithUnAtExit(dtorStub);
 
   llvm::Value *NeedsDestruct = CGF.Builder.CreateIsNull(V, "needs_destruct");

clang/test/CodeGenCXX/aix-static-init-debug-info.cpp

+// RUN: %clang_cc1 -triple powerpc-ibm-aix-xcoff -emit-llvm -x c++ \
+// RUN:     -debug-info-kind=limited < %s | \
+// RUN:   FileCheck --check-prefixes=CHECK,CHECK64 %s
+
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix-xcoff -emit-llvm -x c++ \
+// RUN:     -debug-info-kind=limited  < %s | \
+// RUN:   FileCheck --check-prefixes=CHECK,CHECK64 %s
+
+struct X {
+  X();
+  ~X();
+};
+
+X v;
+
+// CHECK: define internal void @__cxx_global_var_init() [[ATTR:#[0-9]+]] !dbg ![[DBGVAR16:[0-9]+]] {
+// CHECK: entry:
+// CHECK:   call void @_ZN1XC1Ev(%struct.X* @v), !dbg ![[DBGVAR19:[0-9]+]]
+// CHECK:   %0 = call i32 @atexit(void ()* @__dtor_v) [[ATTR:#[0-9]+]], !dbg ![[DBGVAR19]]
+// CHECK:   ret void, !dbg ![[DBGVAR19]]
+// CHECK: }
+
+// CHECK: define internal void @__dtor_v() [[ATTR:#[0-9]+]] !dbg ![[DBGVAR20:[0-9]+]] {
+// CHECK: entry:
+// CHECK:   call void @_ZN1XD1Ev(%struct.X* @v), !dbg ![[DBGVAR21:[0-9]+]]
+// CHECK:   ret void, !dbg ![[DBGVAR21]]
+// CHECK: }
+
+// CHECK: define internal void @__finalize_v() [[ATTR:#[0-9]+]] !dbg ![[DBGVAR22:[0-9]+]] {
+// CHECK: entry:
+// CHECK:   %0 = call i32 @unatexit(void ()* @__dtor_v) [[ATTR:#[0-9]+]], !dbg ![[DBGVAR24:[0-9]+]]
+// CHECK:   %needs_destruct = icmp eq i32 %0, 0, !dbg ![[DBGVAR24]]
+// CHECK:   br i1 %needs_destruct, label %destruct.call, label %destruct.end, !dbg ![[DBGVAR24]]
+
+// CHECK: destruct.call:
+// CHECK:   call void @__dtor_v(), !dbg ![[DBGVAR24]]
+// CHECK:   br label %destruct.end, !dbg ![[DBGVAR24]]
+
+// CHECK: destruct.end:
+// CHECK:   ret void, !dbg ![[DBGVAR24]]
+// CHECK: }
+
+// CHECK: define void @__sinit80000000_clang_c3236cbaa79f2bae3a15e6379a05f625() [[ATTR:#[0-9]+]] !dbg ![[DBGVAR25:[0-9]+]] {
+// CHECK: entry:
+// CHECK:   call void @__cxx_global_var_init(), !dbg ![[DBGVAR26:[0-9]+]]
+// CHECK:   ret void
+// CHECK: }
+
+// CHECK: define void @__sterm80000000_clang_c3236cbaa79f2bae3a15e6379a05f625() [[ATTR:#[0-9]+]] !dbg ![[DBGVAR27:[0-9]+]] {
+// CHECK: entry:
+// CHECK:   call void @__finalize_v(), !dbg ![[DBGVAR28:[0-9]+]]
+// CHECK:   ret void
+// CHECK: }
+
+// CHECK: ![[DBGVAR16]] = distinct !DISubprogram(name: "__cxx_global_var_init", scope: !{{[0-9]+}}, file: !{{[0-9]+}}, line: 14, type: !{{[0-9]+}}, scopeLine: 14, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !{{[0-9]+}}, retainedNodes: !{{[0-9]+}})
+// CHECK: ![[DBGVAR19]] = !DILocation(line: 14, column: 3, scope: ![[DBGVAR16]])
+// CHECK: ![[DBGVAR20]] = distinct !DISubprogram(name: "__dtor_v", scope: !{{[0-9]+}}, file: !{{[0-9]+}}, line: 14, type: !{{[0-9]+}}, scopeLine: 14, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !{{[0-9]+}}, retainedNodes: !{{[0-9]+}})
+// CHECK: ![[DBGVAR21]] = !DILocation(line: 14, column: 3, scope: ![[DBGVAR20]])
+// CHECK: ![[DBGVAR22]] = distinct !DISubprogram(linkageName: "__finalize_v", scope: !{{[0-9]+}}, file: !{{[0-9]+}}, line: 14, type: !{{[0-9]+}}, scopeLine: 14, flags: DIFlagArtificial, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !{{[0-9]+}}, retainedNodes: !{{[0-9]+}})
+// CHECK: ![[DBGVAR24]] = !DILocation(line: 14, column: 3, scope: ![[DBGVAR22]])
+// CHECK: ![[DBGVAR25]] = distinct !DISubprogram(linkageName: "__sinit80000000_clang_c3236cbaa79f2bae3a15e6379a05f625", scope: !{{[0-9]+}}, file: !{{[0-9]+}}, type: !{{[0-9]+}}, flags: DIFlagArtificial, spFlags: DISPFlagDefinition, unit: !{{[0-9]+}}, retainedNodes: !{{[0-9]+}})
+// CHECK: ![[DBGVAR26]] = !DILocation(line: 0, scope: ![[DBGVAR25]])
+// CHECK: ![[DBGVAR27]] = distinct !DISubprogram(linkageName: "__sterm80000000_clang_c3236cbaa79f2bae3a15e6379a05f625", scope: !{{[0-9]+}}, file: !{{[0-9]+}}, type: !{{[0-9]+}}, flags: DIFlagArtificial, spFlags: DISPFlagDefinition, unit: !{{[0-9]+}}, retainedNodes: !{{[0-9]+}})
+// CHECK: ![[DBGVAR28]] = !DILocation(line: 0, scope: ![[DBGVAR27]])