[WebAssembly] Initial WebAssembly support in clang

This implements basic support for compiling (though not yet assembling
or linking) for a WebAssembly target. Note that ABI details are not yet
finalized, and may change.

Differential Revision: http://reviews.llvm.org/D12002


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@246814 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 89 insertions, 3 deletions

diff --git a/include/clang/Basic/BuiltinsWebAssembly.def b/include/clang/Basic/BuiltinsWebAssembly.def
new file mode 100644
index 0000000000..5c67bdfbb4
--- /dev/null
+++ b/include/clang/Basic/BuiltinsWebAssembly.def
@@ -0,0 +1,21 @@
+// BuiltinsWebAssembly.def - WebAssembly builtin function database -*- C++ -*-//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief This file defines the WebAssembly-specific builtin function database.
+/// Users of this file must define the BUILTIN macro to make use of this
+/// information.
+///
+//===----------------------------------------------------------------------===//
+
+// The format of this database matches clang/Basic/Builtins.def.
+
+BUILTIN(__builtin_wasm_page_size, "z", "nc")
+
+#undef BUILTIN
diff --git a/include/clang/Basic/TargetBuiltins.h b/include/clang/Basic/TargetBuiltins.h
index b4740c5952..623c0b64db 100644
--- a/include/clang/Basic/TargetBuiltins.h
+++ b/include/clang/Basic/TargetBuiltins.h
@@ -185,6 +185,17 @@ namespace clang {
         LastTSBuiltin
     };
   }
+
+  /// \brief WebAssembly builtins
+  namespace WebAssembly {
+    enum {
+      LastTIBuiltin = clang::Builtin::FirstTSBuiltin-1,
+#define BUILTIN(ID, TYPE, ATTRS) BI##ID,
+#include "clang/Basic/BuiltinsWebAssembly.def"
+      LastTSBuiltin
+    };
+  }
+
 } // end namespace clang.
 
 #endif
diff --git a/include/clang/Basic/TargetCXXABI.h b/include/clang/Basic/TargetCXXABI.h
index 6921750b84..46243beb46 100644
--- a/include/clang/Basic/TargetCXXABI.h
+++ b/include/clang/Basic/TargetCXXABI.h
@@ -85,6 +85,21 @@ public:
     ///   - representation of member function pointers adjusted as in ARM.
     GenericMIPS,
 
+    /// The WebAssembly ABI is a modified version of the Itanium ABI.
+    ///
+    /// The changes from the Itanium ABI are:
+    ///   - representation of member function pointers is adjusted, as in ARM;
+    ///   - member functions are not specially aligned;
+    ///   - constructors and destructors return 'this', as in ARM;
+    ///   - guard variables are 32-bit on wasm32, as in ARM;
+    ///   - unused bits of guard variables are reserved, as in ARM;
+    ///   - inline functions are never key functions, as in ARM;
+    ///   - C++11 POD rules are used for tail padding, as in iOS64.
+    ///
+    /// TODO: At present the WebAssembly ABI is not considered stable, so none
+    /// of these details is necessarily final yet.
+    WebAssembly,
+
     /// The Microsoft ABI is the ABI used by Microsoft Visual Studio (and
     /// compatible compilers).
     ///
@@ -121,6 +136,7 @@ public:
     case iOS:
     case iOS64:
     case GenericMIPS:
+    case WebAssembly:
       return true;
 
     case Microsoft:
@@ -138,6 +154,7 @@ public:
     case iOS:
     case iOS64:
     case GenericMIPS:
+    case WebAssembly:
       return false;
 
     case Microsoft:
@@ -146,6 +163,35 @@ public:
     llvm_unreachable("bad ABI kind");
   }
 
+  /// \brief Are member functions differently aligned?
+  ///
+  /// Many Itanium-style C++ ABIs require member functions to be aligned, so
+  /// that a pointer to such a function is guaranteed to have a zero in the
+  /// least significant bit, so that pointers to member functions can use that
+  /// bit to distinguish between virtual and non-virtual functions. However,
+  /// some Itanium-style C++ ABIs differentiate between virtual and non-virtual
+  /// functions via other means, and consequently don't require that member
+  /// functions be aligned.
+  bool areMemberFunctionsAligned() const {
+    switch (getKind()) {
+    case WebAssembly:
+      // WebAssembly doesn't require any special alignment for member functions.
+      return false;
+    case GenericARM:
+    case GenericAArch64:
+    case GenericMIPS:
+      // TODO: ARM-style pointers to member functions put the discriminator in
+      //       the this adjustment, so they don't require functions to have any
+      //       special alignment and could therefore also return false.
+    case GenericItanium:
+    case iOS:
+    case iOS64:
+    case Microsoft:
+      return true;
+    }
+    llvm_unreachable("bad ABI kind");
+  }
+
   /// \brief Is the default C++ member function calling convention
   /// the same as the default calling convention?
   bool isMemberFunctionCCDefault() const {
@@ -214,6 +260,7 @@ public:
     switch (getKind()) {
     case GenericARM:
     case iOS64:
+    case WebAssembly:
       return false;
 
     case GenericAArch64:
@@ -261,7 +308,7 @@ public:
     switch (getKind()) {
     // To preserve binary compatibility, the generic Itanium ABI has
     // permanently locked the definition of POD to the rules of C++ TR1,
-    // and that trickles down to all the derived ABIs.
+    // and that trickles down to derived ABIs.
     case GenericItanium:
     case GenericAArch64:
     case GenericARM:
@@ -269,9 +316,10 @@ public:
     case GenericMIPS:
       return UseTailPaddingUnlessPOD03;
 
-    // iOS on ARM64 uses the C++11 POD rules.  It does not honor the
-    // Itanium exception about classes with over-large bitfields.
+    // iOS on ARM64 and WebAssembly use the C++11 POD rules.  They do not honor
+    // the Itanium exception about classes with over-large bitfields.
     case iOS64:
+    case WebAssembly:
       return UseTailPaddingUnlessPOD11;
 
     // MSVC always allocates fields in the tail-padding of a base class
diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index abea885114..8f69c5b88d 100644
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -80,6 +80,8 @@ def m_hexagon_Features_Group  : OptionGroup<"<m hexagon features group>">, Group
 def m_arm_Features_Group  : OptionGroup<"<m arm features group>">, Group<m_Group>;
 def m_aarch64_Features_Group  : OptionGroup<"<m aarch64 features group>">, Group<m_Group>;
 def m_ppc_Features_Group  : OptionGroup<"<m ppc features group>">, Group<m_Group>;
+def m_wasm_Features_Group : OptionGroup<"<m wasm features group>">,
+                                        Group<m_Group>;
 def m_libc_Group          : OptionGroup<"<m libc group>">, Group<m_Group>;
 def u_Group               : OptionGroup<"<u group>">;
 
@@ -1334,6 +1336,9 @@ def mno_fix_cortex_a53_835769 : Flag<["-"], "mno-fix-cortex-a53-835769">,
 def ffixed_x18 : Flag<["-"], "ffixed-x18">, Group<m_aarch64_Features_Group>,
   HelpText<"Reserve the x18 register (AArch64 only)">;
 
+def msimd128 : Flag<["-"], "msimd128">, Group<m_wasm_Features_Group>;
+def mno_simd128 : Flag<["-"], "mno-simd128">, Group<m_wasm_Features_Group>;
+
 def mvsx : Flag<["-"], "mvsx">, Group<m_ppc_Features_Group>;
 def mno_vsx : Flag<["-"], "mno-vsx">, Group<m_ppc_Features_Group>;
 def mpower8_vector : Flag<["-"], "mpower8-vector">,
diff --git a/include/clang/module.modulemap b/include/clang/module.modulemap
index 6b77adb002..cd509efc74 100644
--- a/include/clang/module.modulemap
+++ b/include/clang/module.modulemap
@@ -35,6 +35,7 @@ module Clang_Basic {
   textual header "Basic/BuiltinsPPC.def"
   textual header "Basic/BuiltinsR600.def"
   textual header "Basic/BuiltinsSystemZ.def"
+  textual header "Basic/BuiltinsWebAssembly.def"
   textual header "Basic/BuiltinsX86.def"
   textual header "Basic/BuiltinsXCore.def"
   textual header "Basic/DiagnosticOptions.def"