[cfe-commits] r65141 - /cfe/trunk/lib/CodeGen/CGCall.cpp

[Daniel Dunbar]

Author: ddunbar
Date: Fri Feb 20 12:54:31 2009
New Revision: 65141

URL: http://llvm.org/viewvc/llvm-project?rev=65141&view=rev
Log:
Take advantage of noreturn attribute to add unreachable instruction &
clear insertion point. The rest of IRgen should theoretically take
advantage of this to avoid emitting dead code. Theory != Practice.

Modified:
    cfe/trunk/lib/CodeGen/CGCall.cpp

Modified: cfe/trunk/lib/CodeGen/CGCall.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGCall.cpp?rev=65141&r1=65140&r2=65141&view=diff

==============================================================================
--- cfe/trunk/lib/CodeGen/CGCall.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGCall.cpp Fri Feb 20 12:54:31 2009
@@ -1760,6 +1760,18 @@
   
   if (const llvm::Function *F = dyn_cast<llvm::Function>(Callee))
     CI->setCallingConv(F->getCallingConv());
+
+  // If the call doesn't return, finish the basic block and clear the
+  // insertion point; this allows the rest of IRgen to discard
+  // unreachable code.
+  if (CI->doesNotReturn()) {
+    Builder.CreateUnreachable();
+    Builder.ClearInsertionPoint();
+
+    // Return a reasonable RValue.
+    return GetUndefRValue(RetTy);
+  }
+
   if (CI->getType() != llvm::Type::VoidTy)
     CI->setName("call");