From 958c61ad2091fc748f9ca089a4a228bc87ded11e Mon Sep 17 00:00:00 2001
From: Coby Tayree <coby.tayree@intel.com>
Date: Wed, 9 Aug 2017 13:31:41 +0000
Subject: [PATCH] [X86][Ms-InlineAsm] Extend MS Dot operator to accept "this" +
 struct/class pointers aliases

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

Differential Revision: https://reviews.llvm.org/D36450


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@310472 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaStmtAsm.cpp       | 27 +++++++++++++++++++--------
 test/CodeGen/ms-inline-asm.c   |  8 ++++++--
 test/CodeGen/ms-inline-asm.cpp | 16 ++++++++++++++++
 3 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/lib/Sema/SemaStmtAsm.cpp b/lib/Sema/SemaStmtAsm.cpp
index c182b35bfa..603f970dbc 100644
--- a/lib/Sema/SemaStmtAsm.cpp
+++ b/lib/Sema/SemaStmtAsm.cpp
@@ -677,22 +677,33 @@ bool Sema::LookupInlineAsmField(StringRef Base, StringRef Member,
   SmallVector<StringRef, 2> Members;
   Member.split(Members, ".");
 
-  LookupResult BaseResult(*this, &Context.Idents.get(Base), SourceLocation(),
-                          LookupOrdinaryName);
+  NamedDecl *FoundDecl = nullptr;
 
-  if (!LookupName(BaseResult, getCurScope()))
-    return true;
-  
-  if(!BaseResult.isSingleResult())
+  // 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 (!FoundDecl)
     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
+      QualType QT = TD->getUnderlyingType();
+      if (const auto *PT = QT->getAs<PointerType>())
+        QT = PT->getPointeeType();
+      RT = QT->getAs<RecordType>();
     } else if (TypeDecl *TD = dyn_cast<TypeDecl>(FoundDecl))
       RT = TD->getTypeForDecl()->getAs<RecordType>();
     else if (FieldDecl *TD = dyn_cast<FieldDecl>(FoundDecl))
diff --git a/test/CodeGen/ms-inline-asm.c b/test/CodeGen/ms-inline-asm.c
index 60dffb02b8..9f6852fd47 100644
--- a/test/CodeGen/ms-inline-asm.c
+++ b/test/CodeGen/ms-inline-asm.c
@@ -527,7 +527,7 @@ void cpuid() {
 typedef struct {
   int a;
   int b;
-} A;
+} A, *pA;
 
 typedef struct {
   int b1;
@@ -539,13 +539,15 @@ typedef struct {
   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:[$$0] .4
@@ -556,6 +558,8 @@ void t39() {
   __asm mov eax, fs:[0] C.c2.b
 // CHECK: mov eax, fs:[$$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}"()
 }
diff --git a/test/CodeGen/ms-inline-asm.cpp b/test/CodeGen/ms-inline-asm.cpp
index a435e4b826..094e34aed2 100644
--- a/test/CodeGen/ms-inline-asm.cpp
+++ b/test/CodeGen/ms-inline-asm.cpp
@@ -180,3 +180,19 @@ void t8() {
   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();
+}
+
-- 
2.40.0