After much consultation aimed at figuring out what this builtin actually

does, document the results and then implement __builtin_extend_pointer for
platforms where it's a no-op.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@97540 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Basic/Builtins.def b/include/clang/Basic/Builtins.def
index 3251ec4b1f97bfd9c42fe97114abe3bfd335f55e..ac1660a6eafd8857d712eb67e70f4c85beb5b77a 100644 (file)
--- a/include/clang/Basic/Builtins.def
+++ b/include/clang/Basic/Builtins.def
@@ -317,7 +317,7 @@ BUILTIN(__builtin_frob_return_addr, "v*v*", "n")
 BUILTIN(__builtin_dwarf_cfa, "v*", "n")
 BUILTIN(__builtin_init_dwarf_reg_size_table, "vv*", "n")
 BUILTIN(__builtin_dwarf_sp_column, "Ui", "n")
-BUILTIN(__builtin_extend_pointer, "iv*", "n")
+BUILTIN(__builtin_extend_pointer, "zv*", "n") // Really _Unwind_Ptr -> _Unwind_Word
 
 // GCC Object size checking builtins
 BUILTIN(__builtin_object_size, "zv*i", "n")

diff --git a/lib/CodeGen/CGBuiltin.cpp b/lib/CodeGen/CGBuiltin.cpp
index beaf7b89c003b93e77502f1f8a7ceff7fba3f166..1956abf39f362ad83e35d8e849a36e847db4e1f2 100644 (file)
--- a/lib/CodeGen/CGBuiltin.cpp
+++ b/lib/CodeGen/CGBuiltin.cpp
@@ -365,6 +365,22 @@ RValue CodeGenFunction::EmitBuiltinExpr(const FunctionDecl *FD,
     Value *F = CGM.getIntrinsic(Intrinsic::eh_unwind_init, 0, 0);
     return RValue::get(Builder.CreateCall(F));
   }
+  case Builtin::BI__builtin_extend_pointer: {
+    // Extends a pointer to the size of an _Unwind_Word, which is
+    // generally a uint64_t.  Generally this gets poked directly into
+    // a register (or a "register" depending on platform) and then
+    // called, so if the pointer is shorter than a word we need to
+    // zext / sext based on the platform's expectations for pointers
+    // in registers.
+    //
+    // See: http://gcc.gnu.org/ml/gcc-bugs/2002-02/msg00237.html
+    //
+    // FIXME: ptrtoint always zexts; use a target hook if we start
+    // supporting targets where this matters.
+    Value *Ptr = EmitScalarExpr(E->getArg(0));
+    const llvm::Type *Ty = CGM.getTypes().ConvertType(E->getType());
+    return RValue::get(Builder.CreatePtrToInt(Ptr, Ty));
+  }
 #if 0
   // FIXME: Finish/enable when LLVM backend support stabilizes
   case Builtin::BI__builtin_setjmp: {