Introduce an Emscripten C++ ABI.

Emscripten uses the Itanium C++ ABI for most things, except that it uses
ARM C++ ABI pointers to member functions, to avoid the overhead of aligning
functions.

2 files changed, 12 insertions, 6 deletions

diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 0b03a3c4b6..15e4a50eaa 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -57,6 +57,7 @@ static CGCXXABI &createCXXABI(CodeGenModule &CGM) {
   switch (CGM.getTarget().getCXXABI().getKind()) {
   case TargetCXXABI::GenericAArch64:
   case TargetCXXABI::GenericARM:
+  case TargetCXXABI::Emscripten:
   case TargetCXXABI::iOS:
   case TargetCXXABI::GenericItanium:
     return *CreateItaniumCXXABI(CGM);
diff --git a/lib/CodeGen/ItaniumCXXABI.cpp b/lib/CodeGen/ItaniumCXXABI.cpp
index 3767e4f278..1568284a7d 100644
--- a/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/lib/CodeGen/ItaniumCXXABI.cpp
@@ -231,18 +231,23 @@ CodeGen::CGCXXABI *CodeGen::CreateItaniumCXXABI(CodeGenModule &CGM) {
     return new ItaniumCXXABI(CGM, /* UseARMMethodPtrABI = */ true,
                              /* UseARMGuardVarABI = */ true);
 
+  case TargetCXXABI::Emscripten:
+    // Use ARM-style method pointers so that generated code
+    // does not assume anything about the alignment of function
+    // pointers.
+    return new ItaniumCXXABI(CGM, /* UseARMMethodPtrABI = */ true,
+                             /* UseARMGuardVarABI = */ false);
+
   case TargetCXXABI::GenericItanium:
-    switch (CGM.getContext().getTargetInfo().getTriple().getArch()) {
-    case llvm::Triple::le32:
-    case llvm::Triple::asmjs:
-      // Use ARM-style method pointers so that generated code
+    if (CGM.getContext().getTargetInfo().getTriple().getArch()
+        == llvm::Triple::le32) {
+      // For PNaCl, use ARM-style method pointers so that PNaCl code
       // does not assume anything about the alignment of function
       // pointers.
       return new ItaniumCXXABI(CGM, /* UseARMMethodPtrABI = */ true,
                                /* UseARMGuardVarABI = */ false);
-    default:
-      return new ItaniumCXXABI(CGM);
     }
+    return new ItaniumCXXABI(CGM);
 
   case TargetCXXABI::Microsoft:
     llvm_unreachable("Microsoft ABI is not Itanium-based");