[X86][Ms-InlineAsm] Extend MS Dot operator to accept "this" + struct/class pointers aliases

[coby]

Summary

MS InlineAsm Dot operator accepts "Bases" such as "this" (cpp) and class/struct pointer typedef.
This patch enhance its implementation with this behavior.

[rnk]

lgtm

lib/Sema/SemaStmtAsm.cpp

702–705

This would probably be simpler as:

QualType Ty = TD->getUnderlyingType();
if (const auto *PT = Ty->getAs<PointerType>())
  Ty = PT->getPointeeType();
RT = Ty->getAsRecordType();

... to avoid repeating getAs<RecordType>().

[coby]

lib/Sema/SemaStmtAsm.cpp

702–705

Indeed. thx for pointing it out!

lib/Sema/SemaStmtAsm.cpp

 }
 
 bool Sema::LookupInlineAsmField(StringRef Base, StringRef Member,
                                 unsigned &Offset, SourceLocation AsmLoc) {
   Offset = 0;
   SmallVector<StringRef, 2> Members;
   Member.split(Members, ".");
 
+  NamedDecl *FoundDecl = nullptr;
+
+  // MS InlineAsm uses 'this' as a base
+  if (getLangOpts().CPlusPlus && Base.equals("this")) {
+    if (const Type *PT = getCurrentThisType().getTypePtrOrNull())
+      FoundDecl = PT->getPointeeType()->getAsTagDecl();
+  } else {
     LookupResult BaseResult(*this, &Context.Idents.get(Base), SourceLocation(),
                             LookupOrdinaryName);
+    if (LookupName(BaseResult, getCurScope()) && BaseResult.isSingleResult())
+      FoundDecl = BaseResult.getFoundDecl();
+  }
 
-  if (!LookupName(BaseResult, getCurScope()))
+  if (!FoundDecl)
     return true;
-  
-  if(!BaseResult.isSingleResult())
-    return true;
-  NamedDecl *FoundDecl = BaseResult.getFoundDecl();
   for (StringRef NextMember : Members) {
     const RecordType *RT = nullptr;
     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>();
+      // MS InlineAsm often uses struct pointer aliases as a base
+      const QualType QT = TD->getUnderlyingType();
+      RT = isa<PointerType>(QT) ? QT->getPointeeType()->getAs<RecordType>() :
+                                  QT->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),

test/CodeGen/ms-inline-asm.c

void cpuid() {
   __asm cpuid
 // CHECK-LABEL: define void @cpuid
 // CHECK: call void asm sideeffect inteldialect "cpuid", "~{eax},~{ebx},~{ecx},~{edx},~{dirflag},~{fpsr},~{flags}"()
 }
 
 typedef struct {
   int a;
   int b;
-} A;
+} A, *pA;
 
 typedef struct {
   int b1;
   A   b2;
 } B;
 
 typedef struct {
   int c1;
   A   c2;
   int c3;
   B   c4;
-} C;
+} C, *pC;
 
 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, [eax] pA.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
+  __asm mov eax, [eax]pC.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

test/CodeGen/ms-inline-asm.cpp

static void g() {
       // CHECK-SAME: L__MSASMLABEL_.${:uid}__some_label:
       // CHECK-SAME: nop
       // CHECK-SAME: "~{dirflag},~{fpsr},~{flags}"()
     }
   };
   A::g();
 }
 
+void t9() {
+  // CHECK-LABEL: define void @_Z2t9v()
+  struct A {
+    int a;
+    int b;
+    void g() {
+      __asm mov eax, dword ptr [eax]this.b
+      // CHECK: call void asm sideeffect inteldialect
+      // CHECK-SAME: mov eax, dword ptr [eax].4
+      // CHECK-SAME: "~{eax},~{dirflag},~{fpsr},~{flags}"()
+    }
+  };
+  A AA;
+  AA.g();
+}
+