Add support for composite structs in MS inline asm

[myatsina]

Summary

Add MS inline asm support for structs that contain fields that are also structs.

[mcrosier]

Looks reasonable to me, but I'd prefer Reid take a look before signing off on this one.

[rnk]

lgtm Nice, this is simple. :)

lib/Sema/SemaStmtAsm.cpp

631–634 ↗

(On Diff #43021)

Just for (StringRef NextMember : Members)?

test/CodeGen/ms-inline-asm.c

487 ↗

(On Diff #43021)

Interesting, MSVC rejects this, but we accept. Anyway, it's not relevant to this patch.

[myatsina]

test/CodeGen/ms-inline-asm.c

487 ↗

(On Diff #43021)

I found this comment in X86AsmParser.cpp which might be related:

Parse struct field access. Intel requires a dot, but MSVC doesn't. MSVC
will in fact do global lookup the field name inside all global typedefs,
// but we don't emulate that.

cfe/trunk/lib/Sema/SemaStmtAsm.cpp

if (!Result.get()->isRValue())
     Info.IsVarDecl = true;
 
   return Result;
 }
 
 bool Sema::LookupInlineAsmField(StringRef Base, StringRef Member,
                                 unsigned &Offset, SourceLocation AsmLoc) {
   Offset = 0;
+  SmallVector<StringRef, 2> Members;
+  Member.split(Members, ".");
+
   LookupResult BaseResult(*this, &Context.Idents.get(Base), SourceLocation(),
                           LookupOrdinaryName);
 
   if (!LookupName(BaseResult, getCurScope()))
     return true;
 
-  if (!BaseResult.isSingleResult())
+  LookupResult CurrBaseResult(BaseResult);
+
+  for (StringRef NextMember : Members) {
+
+    if (!CurrBaseResult.isSingleResult())
       return true;
 
     const RecordType *RT = nullptr;
-  NamedDecl *FoundDecl = BaseResult.getFoundDecl();
+    NamedDecl *FoundDecl = CurrBaseResult.getFoundDecl();
     if (VarDecl *VD = dyn_cast<VarDecl>(FoundDecl))
       RT = VD->getType()->getAs<RecordType>();
     else if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(FoundDecl)) {
       MarkAnyDeclReferenced(TD->getLocation(), TD, /*OdrUse=*/false);
       RT = TD->getUnderlyingType()->getAs<RecordType>();
     } else if (TypeDecl *TD = dyn_cast<TypeDecl>(FoundDecl))
       RT = TD->getTypeForDecl()->getAs<RecordType>();
+    else if (FieldDecl *TD = dyn_cast<FieldDecl>(FoundDecl))
+      RT = TD->getType()->getAs<RecordType>();
     if (!RT)
       return true;
 
     if (RequireCompleteType(AsmLoc, QualType(RT, 0), 0))
       return true;
 
-  LookupResult FieldResult(*this, &Context.Idents.get(Member), SourceLocation(),
-                           LookupMemberName);
+    LookupResult FieldResult(*this, &Context.Idents.get(NextMember),
+                             SourceLocation(), LookupMemberName);
 
     if (!LookupQualifiedName(FieldResult, RT->getDecl()))
       return true;
 
     // FIXME: Handle IndirectFieldDecl?
     FieldDecl *FD = dyn_cast<FieldDecl>(FieldResult.getFoundDecl());
     if (!FD)
       return true;
 
+    CurrBaseResult = FieldResult;
+
     const ASTRecordLayout &RL = Context.getASTRecordLayout(RT->getDecl());
     unsigned i = FD->getFieldIndex();
     CharUnits Result = Context.toCharUnitsFromBits(RL.getFieldOffset(i));
-  Offset = (unsigned)Result.getQuantity();
+    Offset += (unsigned)Result.getQuantity();
+  }
 
   return false;
 }
 
 ExprResult
 Sema::LookupInlineAsmVarDeclField(Expr *E, StringRef Member, unsigned &Offset,
                                   llvm::InlineAsmIdentifierInfo &Info,
                                   SourceLocation AsmLoc) {

cfe/trunk/test/CodeGen/ms-inline-asm.c

 // CHECK: call void asm sideeffect inteldialect "cpuid", "~{eax},~{ebx},~{ecx},~{edx},~{dirflag},~{fpsr},~{flags}"()
 }
 
 typedef struct {
   int a;
   int b;
 } A;
 
+typedef struct {
+  int b1;
+  A   b2;
+} B;
+
+typedef struct {
+  int c1;
+  A   c2;
+  int c3;
+  B   c4;
+} C;
+
 void t39() {
 // CHECK-LABEL: define void @t39
   __asm mov eax, [eax].A.b
 // CHECK: mov eax, [eax].4
   __asm mov eax, [eax] A.b
 // CHECK: mov eax, [eax] .4
   __asm mov eax, fs:[0] A.b
 // CHECK: mov eax, fs:[$$0] .4
+  __asm mov eax, [eax].B.b2.a
+// CHECK: mov eax, [eax].4
+  __asm mov eax, [eax] B.b2.b
+// CHECK: mov eax, [eax] .8
+  __asm mov eax, fs:[0] C.c2.b
+// CHECK: mov eax, fs:[$$0] .8
+  __asm mov eax, [eax]C.c4.b2.b
+// CHECK: mov eax, [eax].24
 // CHECK: "~{eax},~{dirflag},~{fpsr},~{flags}"()
 }
 
 void t40(float a) {
 // CHECK-LABEL: define void @t40
   int i;
   __asm fld a
 // CHECK: fld dword ptr $1