[ms] [llvm-ml] Fix MASM support for nested unnamed STRUCTs and UNIONs

[epastor]

Summary

Fix MASM support for nested unnamed STRUCTs and UNIONs

[epastor]

Avoid re-implementing alignTo.

[thakis]

llvm/test/tools/llvm-ml/struct.test

158

Can you add another field after the unnamed struct, just to check that that does the right thing?

llvm/lib/MC/MCParser/MasmParser.cpp

bool MasmParser::parseDirectiveEnds(StringRef Name, SMLoc NameLoc) {
   if (StructInProgress.empty())
     return Error(NameLoc, "ENDS directive without matching STRUC/STRUCT/UNION");
   if (StructInProgress.size() > 1)
     return Error(NameLoc, "unexpected name in nested ENDS directive");
   if (StructInProgress.back().Name.compare_lower(Name))
     return Error(NameLoc, "mismatched name in ENDS directive; expected '" +
                               StructInProgress.back().Name + "'");
   StructInfo Structure = StructInProgress.pop_back_val();
-  if (Structure.Size % Structure.Alignment != 0) {
-    // Pad to make the structure's size divisible by its alignment.
-    Structure.Size +=
-        Structure.Alignment - (Structure.Size % Structure.Alignment);
-  }
+  Structure.Size = llvm::alignTo(Structure.Size, Structure.Alignment);
   Structs[Name.lower()] = Structure;
 
   if (parseToken(AsmToken::EndOfStatement))
     return addErrorSuffix(" in ENDS directive");
 
   return false;
 }
 
 bool MasmParser::parseDirectiveNestedEnds() {
   if (StructInProgress.empty())
     return TokError("ENDS directive without matching STRUC/STRUCT/UNION");
   if (StructInProgress.size() == 1)
     return TokError("missing name in top-level ENDS directive");
 
   if (parseToken(AsmToken::EndOfStatement))
     return addErrorSuffix(" in nested ENDS directive");
 
   StructInfo Structure = StructInProgress.pop_back_val();
-  if (Structure.Size % Structure.Alignment != 0) {
-    // Pad to make the structure's size divisible by its alignment.
-    Structure.Size +=
-        Structure.Alignment - (Structure.Size % Structure.Alignment);
-  }
+  Structure.Size = llvm::alignTo(Structure.Size, Structure.Alignment);
+
   StructInfo &ParentStruct = StructInProgress.back();
+  if (Structure.Name.empty()) {
+    const size_t OldFields = ParentStruct.Fields.size();
+    ParentStruct.Fields.insert(
+        ParentStruct.Fields.end(),
+        std::make_move_iterator(Structure.Fields.begin()),
+        std::make_move_iterator(Structure.Fields.end()));
+    for (const auto &FieldByName : Structure.FieldsByName) {
+      ParentStruct.FieldsByName[FieldByName.getKey()] =
+          FieldByName.getValue() + OldFields;
+    }
+    if (!ParentStruct.IsUnion) {
+      for (auto FieldIter = ParentStruct.Fields.begin() + OldFields;
+           FieldIter != ParentStruct.Fields.end(); ++FieldIter) {
+        FieldIter->Offset += ParentStruct.Size;
+      }
+    }
 
+    if (ParentStruct.IsUnion)
+      ParentStruct.Size = std::max(ParentStruct.Size, Structure.Size);
+    else
+      ParentStruct.Size += Structure.Size;
+  } else {
     FieldInfo &Field = ParentStruct.addField(Structure.Name, FT_STRUCT);
     StructFieldInfo &StructInfo = Field.Contents.StructInfo;
     Field.Type = Structure.Size;
     Field.LengthOf = 1;
     Field.SizeOf = Structure.Size;
 
     if (ParentStruct.IsUnion)
       ParentStruct.Size = std::max(ParentStruct.Size, Field.SizeOf);
     else
       ParentStruct.Size += Field.SizeOf;
 
     StructInfo.Structure = Structure;
     StructInfo.Initializers.emplace_back();
     auto &FieldInitializers = StructInfo.Initializers.back().FieldInitializers;
     for (const auto &SubField : Structure.Fields) {
       FieldInitializers.push_back(SubField.Contents);
     }
+  }
 
   return false;
 }
 
 /// parseDirectiveOrg
 ///  ::= .org expression [ , expression ]
 bool MasmParser::parseDirectiveOrg() {
   const MCExpr *Offset;

llvm/test/tools/llvm-ml/struct.test

 
 ; CHECK: t8:
 ; CHECK-NEXT: mov eax, dword ptr [rip + t2+9]
 ; CHECK-NEXT: mov eax, dword ptr [rip + t2+9]
 ; CHECK-NEXT: mov eax, dword ptr [rip + t2+9]
 ; CHECK-NEXT: mov eax, dword ptr [rip + (t2+8)+1]
 ; CHECK-NEXT: mov eax, dword ptr [rip + t2+9]
 
+QUUX STRUCT
+  u DWORD ?
+  UNION
+    v WORD ?
+    w DWORD ?
+    STRUCT
+      x BYTE ?
+      y BYTE ?
+    ENDS
+  ENDS
+  z DWORD ?
+QUUX ENDS
+
+t9:
+mov eax, [ebx].QUUX.u
+mov eax, [ebx].QUUX.v
+mov eax, [ebx].QUUX.w
+mov eax, [ebx].QUUX.x
+mov eax, [ebx].QUUX.y
+mov eax, [ebx].QUUX.z
+
+; CHECK: t9:
+; CHECK-NEXT: mov eax, dword ptr [ebx]
+; CHECK-NEXT: mov eax, dword ptr [ebx + 4]
+; CHECK-NEXT: mov eax, dword ptr [ebx + 4]
+; CHECK-NEXT: mov eax, dword ptr [ebx + 4]
+; CHECK-NEXT: mov eax, dword ptr [ebx + 5]
+; CHECK-NEXT: mov eax, dword ptr [ebx + 8]
+
 END