add an instcombine pass to clean up after heavy-lifting IP passes


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33843 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/gccld/GenerateCode.cpp b/tools/gccld/GenerateCode.cpp
index db1caa8..e70bda3 100644
--- a/tools/gccld/GenerateCode.cpp
+++ b/tools/gccld/GenerateCode.cpp
@@ -239,6 +239,12 @@
     // Remove unused arguments from functions...
     addPass(Passes, createDeadArgEliminationPass());
 
+    // Reduce the code after globalopt and ipsccp.  Both can open up significant
+    // simplification opportunities, and both can propagate functions through
+    // function pointers.  When this happens, we often have to resolve varargs
+    // calls, etc, so let instcombine do this.
+    addPass(Passes, createInstructionCombiningPass());
+    
     if (!DisableInline)
       addPass(Passes, createFunctionInliningPass()); // Inline small functions