Replace assertions of types on LLVM instructions in the Executor with a

pass that checks these assertions. This improves several things.

* This pass provides more friendly messages than assertions in that it
just emits a warning and carries on checking the rest of the
instructions.

* The takes the checks outside of the Executor's hot path and so avoids
checking the same instruction multiple times. Now each instruction
is only checked once just before execution starts.

The disadvantage of this approach is the check for invariants we expect
to hold have been pulled far away from where we expect them to hold.
After discussion with @ccadar and @MartinNowack it was decided we will
take this hit to readability for better performance and simpler code in
the Executor.

1 files changed, 10 insertions, 0 deletions

diff --git a/lib/Module/KModule.cpp b/lib/Module/KModule.cpp
index bee9a0b4..215b2275 100644
--- a/lib/Module/KModule.cpp
+++ b/lib/Module/KModule.cpp
@@ -390,9 +390,19 @@ void KModule::prepare(const Interpreter::ModuleOptions &opts,
   case eSwitchTypeLLVM:  pm3.add(createLowerSwitchPass()); break;
   default: klee_error("invalid --switch-type");
   }
+  InstructionOperandTypeCheckPass *operandTypeCheckPass =
+      new InstructionOperandTypeCheckPass();
   pm3.add(new IntrinsicCleanerPass(*targetData));
   pm3.add(new PhiCleanerPass());
+  pm3.add(operandTypeCheckPass);
   pm3.run(*module);
+
+  // Enforce the operand type invariants that the Executor expects.  This
+  // implicitly depends on the "Scalarizer" pass to be run in order to succeed
+  // in the presence of vector instructions.
+  if (!operandTypeCheckPass->checkPassed()) {
+    klee_error("Unexpected instruction operand types detected");
+  }
 #if LLVM_VERSION_CODE < LLVM_VERSION(3, 3)
   // For cleanliness see if we can discard any of the functions we
   // forced to import.