PNaCl: Implement computed gotos (indirectbr) by expanding out to switches

lib/Transforms/NaCl/PNaClABISimplify.cpp

 //===-- PNaClABISimplify.cpp - Lists PNaCl ABI simplification passes ------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the meta-passes "-pnacl-abi-simplify-preopt"
@@ skipping 29 matching lines @@
     PM.add(createLowerInvokePass());
     // Remove landingpad blocks made unreachable by LowerInvoke.
     PM.add(createCFGSimplificationPass());
   }
 
   // Internalize all symbols in the module except _start, which is the only
   // symbol a stable PNaCl pexe is allowed to export.
   const char *SymbolsToPreserve[] = { "_start" };
   PM.add(createInternalizePass(SymbolsToPreserve));
 
+  // Expand out computed gotos (indirectbr and blockaddresses) into switches.
+  PM.add(createExpandIndirectBrPass());
+
   // LowerExpect converts Intrinsic::expect into branch weights,
   // which can then be removed after BlockPlacement.
   PM.add(createLowerExpectIntrinsicPass());
   // Rewrite unsupported intrinsics to simpler and portable constructs.
   PM.add(createRewriteLLVMIntrinsicsPass());
 
   // Expand out some uses of struct types.
   PM.add(createExpandArithWithOverflowPass());
   // ExpandStructRegs must be run after ExpandArithWithOverflow to
   // expand out the insertvalue instructions that
@@ skipping 68 matching lines @@
   // Strip dead prototytes to appease the intrinsic ABI checks.
   // ExpandVarArgs leaves around vararg intrinsics, and
   // ReplacePtrsWithInts leaves the lifetime.start/end intrinsics.
   PM.add(createStripDeadPrototypesPass());
 
   // Eliminate simple dead code that the post-opt passes could have
   // created.
   PM.add(createDeadInstEliminationPass());
   PM.add(createDeadCodeEliminationPass());
 }