[OpenMP] Correctly add member expressions to OpenMP info

[jhuber6]

Summary

Mapping expressions that have this as their base expression aren't
considered a valid base variable and the rest of the runtime expects
this. However, if we have an expression with no value declaration we can
try to extract it manually to provide more helpful debuggin information.

[jdoerfert]

LG, one nit.

clang/lib/CodeGen/CGOpenMPRuntime.cpp

9439

[jhuber6]

Add static.

clang/lib/CodeGen/CGOpenMPRuntime.cpp

llvm::Value *P = CGF.Builder.CreateConstInBoundsGEP2_32(
         llvm::ArrayType::get(CGM.VoidPtrTy, Info.NumberOfPtrs),
         Info.PointersArray, 0, I);
     Address PAddr(P, CGF.getPointerAlign());
     CGF.Builder.CreateStore(DAddr.getPointer(), PAddr);
     ++L;
   }
 }
 
+// Try to extract the base declaration from a `this->x` expression if possible.
+static ValueDecl *getDeclFromThisExpr(const Expr *E) {
+  if (!E)
+    return nullptr;
+
+  if (const auto *OASE = dyn_cast<OMPArraySectionExpr>(E->IgnoreParenCasts()))
+    if (const MemberExpr *ME =
+            dyn_cast<MemberExpr>(OASE->getBase()->IgnoreParenImpCasts()))
+      return ME->getMemberDecl();
+  return nullptr;
+}
+
 /// Emit a string constant containing the names of the values mapped to the
 /// offloading runtime library.
 llvm::Constant *
 emitMappingInformation(CodeGenFunction &CGF, llvm::OpenMPIRBuilder &OMPBuilder,
                        MappableExprsHandler::MappingExprInfo &MapExprs) {
-  llvm::Constant *SrcLocStr;
-  if (!MapExprs.getMapDecl()) {
-    SrcLocStr = OMPBuilder.getOrCreateDefaultSrcLocStr();
+
+  if (!MapExprs.getMapDecl() && !MapExprs.getMapExpr())
+    return OMPBuilder.getOrCreateDefaultSrcLocStr();
+
+  SourceLocation Loc;
+  if (!MapExprs.getMapDecl() && MapExprs.getMapExpr()) {
+    if (const ValueDecl *VD = getDeclFromThisExpr(MapExprs.getMapExpr()))
+      Loc = VD->getLocation();
+    else
+      Loc = MapExprs.getMapExpr()->getExprLoc();
   } else {
-    std::string ExprName = "";
-    if (MapExprs.getMapExpr()) {
-      PrintingPolicy P(CGF.getContext().getLangOpts());
-      llvm::raw_string_ostream OS(ExprName);
-      MapExprs.getMapExpr()->printPretty(OS, nullptr, P);
-      OS.flush();
-    } else {
-      ExprName = MapExprs.getMapDecl()->getNameAsString();
-    }
+    Loc = MapExprs.getMapDecl()->getLocation();
+  }
+
 
-    SourceLocation Loc = MapExprs.getMapDecl()->getLocation();
-    PresumedLoc PLoc = CGF.getContext().getSourceManager().getPresumedLoc(Loc);
-    const char *FileName = PLoc.getFilename();
-    unsigned Line = PLoc.getLine();
-    unsigned Column = PLoc.getColumn();
-    SrcLocStr = OMPBuilder.getOrCreateSrcLocStr(FileName, ExprName.c_str(),
-                                                Line, Column);
-  }
-  return SrcLocStr;
+  return OMPBuilder.getOrCreateSrcLocStr(PLoc.getFilename(), ExprName.c_str(),
+                                         PLoc.getLine(), PLoc.getColumn());
 }
 
 /// Emit the arrays used to pass the captures and map information to the
 /// offloading runtime library. If there is no map or capture information,
 /// return nullptr by reference.
 static void emitOffloadingArrays(
     CodeGenFunction &CGF, MappableExprsHandler::MapCombinedInfoTy &CombinedInfo,
     CGOpenMPRuntime::TargetDataInfo &Info, llvm::OpenMPIRBuilder &OMPBuilder,

clang/test/OpenMP/target_map_names.cpp

 #pragma omp target update to(t)
 
 #pragma omp target update from(t) nowait
 
 #pragma omp target update to(t) nowait
 }
 
 struct S3 {
+  S3() {
+#pragma omp target data map(alloc : Z[0:64])
+    { }
+  }
   double Z[64];
 };
 
 #pragma omp declare mapper(id: S3 s) map(s.Z[0:64])
 
 void qux() {
   S3 s;
 #pragma omp target map(mapper(id), to:s)
   { }
 }
 
+
+
 // DEBUG: @{{[0-9]+}} = private unnamed_addr constant [{{[0-9]+}} x i8] c";s.Z[0:64];{{.*}}.cpp;{{[0-9]+}};{{[0-9]+}};;\00"
+// DEBUG: @{{[0-9]+}} = private unnamed_addr constant [{{[0-9]+}} x i8] c";this->Z[0:64];{{.*}}.cpp;{{[0-9]+}};{{[0-9]+}};;\00"
 
 // Clang used to mistakenly generate the map name "x" for both x and y on this
 // directive.  Conditions to reproduce the bug: a single map clause has two
 // variables, and at least the second is used in the associated statement.
 //
 // DEBUG: @{{[0-9]+}} = private unnamed_addr constant [{{[0-9]+}} x i8] c";x;{{.*}}.cpp;[[@LINE+3]];7;;\00"
 // DEBUG: @{{[0-9]+}} = private unnamed_addr constant [{{[0-9]+}} x i8] c";y;{{.*}}.cpp;[[@LINE+2]];10;;\00"
 void secondMapNameInClause() {