Instruction Combination can create a ton of trivially dead instructions. Remove

them with an DIE pass before more expensive optimizations are run.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2491 91177308-0d34-0410-b5e6-96231b3b80d8

tools/gccas/gccas.cpp

@@ -83,6 +83,7 @@ int main(int argc, char **argv) {
     Passes.add(createRaisePointerReferencesPass()); // Eliminate casts
     Passes.add(createPromoteMemoryToRegister());    // Promote alloca's to regs
     Passes.add(createInstructionCombiningPass());   // Combine silly seq's
+    Passes.add(createDeadInstEliminationPass());    // Kill InstCombine remnants
     Passes.add(createSCCPPass());                   // Constant prop with SCCP
     Passes.add(createGCSEPass());                   // Remove common subexprs
     Passes.add(createDeadCodeEliminationPass());    // Remove Dead code/vars