Convert calls to Rust's panic functions to a call to a marker (#763)

This removes the calls to panic functions called by Rust programs. Removing the calls enables dead code elimination to remove the arguments flowing into the panic function call.

Author: keram88

include/smack/Naming.h

@@ -98,6 +98,7 @@ class Naming {
   static const std::string RUST_LANG_START_INTERNAL;
   static const std::vector<std::string> RUST_PANICS;
   static const std::string RUST_PANIC_ANNOTATION;
+  static const std::string RUST_PANIC_MARKER;
 
   static const std::string INT_WRAP_SIGNED_FUNCTION;
   static const std::string INT_WRAP_UNSIGNED_FUNCTION;

lib/smack/Naming.cpp

@@ -72,6 +72,8 @@ const std::vector<std::string> Naming::RUST_PANICS = {
 
 const std::string Naming::RUST_PANIC_ANNOTATION = "rust_panic";
 
+const std::string Naming::RUST_PANIC_MARKER = "__SMACK_RUST_PANIC_MARKER";
+
 const std::string Naming::BLOCK_LBL = "$bb";
 const std::string Naming::RET_VAR = "$r";
 const std::string Naming::EXN_VAR = "$exn";

lib/smack/RustFixes.cpp

@@ -27,7 +27,9 @@ bool isRustNameMatch(StringRef search, StringRef name) {
   return hashed_match || exact_match;
 }
 
-bool replaceRustMemoryFunctions(Function &f) {
+bool replaceSpecialRustFunctions(Function &f) {
+  std::vector<Instruction *> to_remove;
+
   bool changed = false;
   static const std::map<StringRef, StringRef> alloc_fns = {
       {"_ZN5alloc5alloc5alloc17h", "__smack_rust_std_alloc"},
@@ -53,9 +55,27 @@ bool replaceRustMemoryFunctions(Function &f) {
             ci->setCalledFunction(replacement);
           }
         }
+
+        if (Naming::isRustPanic(name)) {
+          // Remove the calls rust panic functions
+          changed = true;
+          // Keep track of the panic call
+          Module *m = f->getParent();
+          FunctionCallee marker = m->getOrInsertFunction(
+              Naming::RUST_PANIC_MARKER, Type::getVoidTy(m->getContext()));
+          CallInst *panic_marker = CallInst::Create(marker);
+          panic_marker->setDebugLoc(ci->getDebugLoc());
+          panic_marker->insertBefore(ci);
+          to_remove.push_back(ci);
+        }
       }
     }
   }
+
+  for (auto ci : to_remove) {
+    ci->eraseFromParent();
+  }
+
   return changed;
 }
 
@@ -127,7 +147,7 @@ bool RustFixes::runOnFunction(Function &F) {
     if (name == "main") {
       result |= fixEntry(F);
     }
-    result |= replaceRustMemoryFunctions(F);
+    result |= replaceSpecialRustFunctions(F);
   }
 
   return result;

lib/smack/SmackInstGenerator.cpp

@@ -648,7 +648,7 @@ void SmackInstGenerator::visitCallInst(llvm::CallInst &ci) {
 
   StringRef name = f->hasName() ? f->getName() : "";
 
-  if (SmackOptions::RustPanics && Naming::isRustPanic(name) &&
+  if (SmackOptions::RustPanics && name == Naming::RUST_PANIC_MARKER &&
       SmackOptions::shouldCheckFunction(
           ci.getParent()->getParent()->getName())) {
     // Convert Rust's panic functions into assertion violations