From e7f26a94b0b51bb267a963fd414a5a0bda4ff051 Mon Sep 17 00:00:00 2001
From: Martin <noone@nowhere.com>
Date: Sun, 6 Dec 2015 18:47:16 +0100
Subject: [PATCH] Prepare generic x86 TargetABI for proper MSVC support

Based on Rainer's work in
https://github.com/rainers/ldc/commit/3e36652c2cc2016d1c7dd8ff7229678671fa1706
---
 dmd2/cppmangle.c    | 5 ++++-
 gen/abi-aarch64.cpp | 3 ++-
 gen/abi-x86.cpp     | 8 ++++++--
 gen/abi.h           | 4 +++-
 gen/functions.cpp   | 2 +-
 gen/target.cpp      | 4 +++-
 gen/tocall.cpp      | 4 ++--
 7 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/dmd2/cppmangle.c b/dmd2/cppmangle.c
index a37641a919..44cfd24d87 100644
--- a/dmd2/cppmangle.c
+++ b/dmd2/cppmangle.c
@@ -1339,6 +1339,9 @@ public:
 
     char *mangleOf(Dsymbol *s)
     {
+#if IN_LLVM
+        buf.writeByte('\01'); // disable further mangling by the backend
+#endif
         VarDeclaration *vd = s->isVarDeclaration();
         FuncDeclaration *fd = s->isFuncDeclaration();
         if (vd)
@@ -1991,7 +1994,7 @@ char *toCppMangle(Dsymbol *s)
     const bool isTargetWindowsMSVC = global.params.targetTriple.isWindowsMSVCEnvironment();
     if (isTargetWindowsMSVC)
     {
-        VisualCPPMangler v(!global.params.is64bit);
+        VisualCPPMangler v(false);
         return v.mangleOf(s);
     }
     else
diff --git a/gen/abi-aarch64.cpp b/gen/abi-aarch64.cpp
index 7891c7bea4..0f4b128090 100644
--- a/gen/abi-aarch64.cpp
+++ b/gen/abi-aarch64.cpp
@@ -17,7 +17,8 @@
 #include "gen/abi-aarch64.h"
 
 struct AArch64TargetABI : TargetABI {
-  llvm::CallingConv::ID callingConv(LINK l) {
+  llvm::CallingConv::ID callingConv(llvm::FunctionType *ft, LINK l,
+                                    FuncDeclaration *fdecl = nullptr) override {
     switch (l) {
     case LINKc:
     case LINKcpp:
diff --git a/gen/abi-x86.cpp b/gen/abi-x86.cpp
index 607ceea9f7..5e08508e2d 100644
--- a/gen/abi-x86.cpp
+++ b/gen/abi-x86.cpp
@@ -29,11 +29,15 @@ struct X86TargetABI : TargetABI {
       : isOSX(global.params.isOSX),
         isMSVC(global.params.targetTriple.isWindowsMSVCEnvironment()) {}
 
-  llvm::CallingConv::ID callingConv(llvm::FunctionType *ft, LINK l) override {
+  llvm::CallingConv::ID callingConv(llvm::FunctionType *ft, LINK l,
+                                    FuncDeclaration *fdecl = nullptr) override {
     switch (l) {
     case LINKc:
-    case LINKcpp:
       return llvm::CallingConv::C;
+    case LINKcpp:
+      return isMSVC && !ft->isVarArg() && fdecl && fdecl->isThis()
+                 ? llvm::CallingConv::X86_ThisCall
+                 : llvm::CallingConv::C;
     case LINKd:
     case LINKdefault:
     case LINKpascal:
diff --git a/gen/abi.h b/gen/abi.h
index 878e28d76c..a4b46a3e6e 100644
--- a/gen/abi.h
+++ b/gen/abi.h
@@ -26,6 +26,7 @@ class TypeFunction;
 struct IrFuncTy;
 struct IrFuncTyArg;
 class DValue;
+class FuncDeclaration;
 
 namespace llvm {
 class Type;
@@ -81,7 +82,8 @@ struct TargetABI {
 
   /// Returns the LLVM calling convention to be used for the given D linkage
   /// type on the target. Defaults to the C calling convention.
-  virtual llvm::CallingConv::ID callingConv(llvm::FunctionType *ft, LINK l) {
+  virtual llvm::CallingConv::ID callingConv(llvm::FunctionType *ft, LINK l,
+                                            FuncDeclaration *fdecl = nullptr) {
     return llvm::CallingConv::C;
   }
 
diff --git a/gen/functions.cpp b/gen/functions.cpp
index 97d92dac01..256fd41df7 100644
--- a/gen/functions.cpp
+++ b/gen/functions.cpp
@@ -463,7 +463,7 @@ void DtoDeclareFunction(FuncDeclaration *fdecl) {
     fatal();
   }
 
-  func->setCallingConv(gABI->callingConv(func->getFunctionType(), link));
+  func->setCallingConv(gABI->callingConv(func->getFunctionType(), link, fdecl));
 
   IF_LOG Logger::cout() << "func = " << *func << std::endl;
 
diff --git a/gen/target.cpp b/gen/target.cpp
index 132b36e735..9cb3b603fd 100644
--- a/gen/target.cpp
+++ b/gen/target.cpp
@@ -37,7 +37,9 @@ void Target::init() {
   c_longsize = global.params.is64bit ? 8 : 4;
   c_long_doublesize = realsize;
 
-  reverseCppOverloads = false; // DMC is not supported.
+  // according to DMD, only for 32-bit MSVC++:
+  reverseCppOverloads = !global.params.is64bit &&
+                        global.params.targetTriple.isWindowsMSVCEnvironment();
 }
 
 /******************************
diff --git a/gen/tocall.cpp b/gen/tocall.cpp
index 523cc54d09..87a8d91f0c 100644
--- a/gen/tocall.cpp
+++ b/gen/tocall.cpp
@@ -777,8 +777,8 @@ DValue *DtoCallFunction(Loc &loc, Type *resulttype, DValue *fnval,
   LLFunctionType *const callableTy =
       DtoExtractFunctionType(callable->getType());
   assert(callableTy);
-  const llvm::CallingConv::ID callconv =
-      gABI->callingConv(callableTy, tf->linkage);
+  const auto callconv = gABI->callingConv(callableTy, tf->linkage,
+                                          dfnval ? dfnval->func : nullptr);
 
   //     IF_LOG Logger::cout() << "callable: " << *callable << '\n';