Llvm 7 build (#469)

* bc: Use llvm::CallSite methods instead of raw llvm instructions.

* bc: Use llvm::CallSite in utils.

* bc: Add compatibility file for CallSite.

* bc: Reflect addition of compat for CallSite.

Author: Aiethel

include/remill/BC/Compat/CallSite.h

@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2021 Trail of Bits, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#pragma once
+
+#include "remill/BC/Version.h"
+
+#include <llvm/IR/Instruction.h>
+
+
+/* In llvm-11 llvm::CallSite got partially replace by llvm::AbstractCallSite
+ * for read-only operations and llvm::CallBase was made public (was considered
+ * implementation before)
+ * This header tries to provide at least some compatibility for what is
+ * currently used.
+ */
+
+#if LLVM_VERSION_NUMBER < LLVM_VERSION(11, 0)
+
+#include <llvm/IR/CallSite.h>
+namespace remill::compat::llvm {
+
+  struct CallSite : private ::llvm::CallSite {
+    using parent = ::llvm::CallSite;
+
+    /* List of "allowed" methods (thanks to private inheritance)
+     * that prevent user from accidentally using functionality that
+     * would break other llvm version.
+     * If you want to add method here, make sure other versions have it
+     * as well.
+     */
+    using parent::parent;
+    using parent::isInvoke;
+    using parent::isCall;
+    using parent::operator bool;
+    using parent::getCalledValue;
+    using parent::getCalledFunction;
+    using parent::setCalledFunction;
+  };
+
+} // namespace remill::compat::llvm
+
+#else
+
+#include <llvm/IR/AbstractCallSite.h>
+namespace remill::compat::llvm {
+
+  struct CallSite {
+    ::llvm::CallBase *cb;
+
+    CallSite(::llvm::Instruction *inst)
+      : cb(::llvm::dyn_cast<::llvm::CallBase>(inst))
+    {}
+
+    CallSite(::llvm::User *user)
+      : CallSite(::llvm::dyn_cast<::llvm::Instruction>(user))
+    {}
+
+    bool isInvoke() const {
+      return ::llvm::isa<::llvm::InvokeInst>(cb);
+    }
+
+    bool isCall() const {
+      return ::llvm::isa<::llvm::CallInst>(cb);
+    }
+
+    ::llvm::Value *getCalledValue() {
+      if (!static_cast<bool>(*this)) {
+        return nullptr;
+      }
+      return cb->getCalledOperand();
+    }
+
+    ::llvm::Function *getCalledFunction() {
+      if ( !*this) {
+        return nullptr;
+      }
+      return cb->getCalledFunction();
+    }
+
+    void setCalledFunction(::llvm::Function *fn) {
+      return cb->setCalledFunction(fn);
+    }
+
+    operator bool() const {
+      return cb;
+    }
+  };
+
+} // namespace remill::compat::llvm
+
+#endif

lib/BC/DeadStoreEliminator.cpp

@@ -36,6 +36,7 @@
 #include <vector>
 
 #include "remill/Arch/Arch.h"
+#include "remill/BC/Compat/CallSite.h"
 #include "remill/BC/Compat/VectorType.h"
 #include "remill/BC/ABI.h"
 #include "remill/BC/Util.h"
@@ -407,20 +408,20 @@ static void StreamCallOrInvokeToDOT(std::ostream &dot,
     dot << "%" << inst.getName().str() << " = ";
   }
 
-  llvm::Value *called_val = nullptr;
-  if (auto call_inst = llvm::dyn_cast<llvm::CallInst>(&inst)) {
-    dot << "call ";
-    called_val = call_inst->getCalledOperand();
-  } else {
-    dot << "invoke ";
-    auto invoke_inst = llvm::dyn_cast<llvm::InvokeInst>(&inst);
-    called_val = invoke_inst->getCalledOperand();
-  }
+  if (auto cs = compat::llvm::CallSite(&inst)) {
+    if (cs.isInvoke()) {
+      dot << "invoke ";
+    } else if (cs.isCall()) {
+      dot << "call";
+    } else {
+      LOG(ERROR) << "Encountered callsite that is not call nor invoke!";
+    }
 
-  if (called_val->getName().empty()) {
-    dot << called_val->getValueID();
-  } else {
-    dot << called_val->getName().str();
+    if(!cs.getCalledValue()->getName().empty()) {
+      dot << cs.getCalledValue()->getName().str();
+    } else {
+      dot << cs.getCalledValue()->getValueID();
+    }
   }
 }
 
@@ -1135,7 +1136,8 @@ VisitResult ForwardAliasVisitor::visitPHINode(llvm::PHINode &inst) {
 }
 
 VisitResult ForwardAliasVisitor::visitCallInst(llvm::CallInst &inst) {
-  const auto val = inst.getCalledOperand()->stripPointerCasts();
+  //const auto val = inst.getCalledOperand()->stripPointerCasts();
+  const auto val = compat::llvm::CallSite(&inst).getCalledValue()->stripPointerCasts();
   if (auto const_val = llvm::dyn_cast<llvm::Constant>(val); const_val) {
 
     // Don't let this affect anything.
@@ -1187,7 +1189,7 @@ VisitResult ForwardAliasVisitor::visitCallInst(llvm::CallInst &inst) {
 }
 
 VisitResult ForwardAliasVisitor::visitInvokeInst(llvm::InvokeInst &inst) {
-  auto val = inst.getCalledOperand()->stripPointerCasts();
+  auto val = compat::llvm::CallSite(&inst).getCalledValue()->stripPointerCasts();
   if (llvm::isa<llvm::InlineAsm>(val)) {
     live_args[&inst].set();  // Weird to invoke inline assembly.
 

lib/BC/Util.cpp

@@ -48,6 +48,7 @@
 #include "remill/BC/ABI.h"
 #include "remill/BC/Annotate.h"
 #include "remill/BC/Compat/BitcodeReaderWriter.h"
+#include "remill/BC/Compat/CallSite.h"
 #include "remill/BC/Compat/DebugInfo.h"
 #include "remill/BC/Compat/GlobalValue.h"
 #include "remill/BC/Compat/IRReader.h"
@@ -694,13 +695,15 @@ void CloneBlockFunctionInto(llvm::Function *func) {
 
 // Returns a list of callers of a specific function.
 std::vector<llvm::CallInst *> CallersOf(llvm::Function *func) {
+  if (!func) {
+    return {};
+  }
+
   std::vector<llvm::CallInst *> callers;
-  if (func) {
-    for (auto user : func->users()) {
-      if (auto call_inst = llvm::dyn_cast<llvm::CallInst>(user)) {
-        if (call_inst->getCalledOperand() == func) {
-          callers.push_back(call_inst);
-        }
+  for (auto user : func->users()) {
+    if (auto cs = compat::llvm::CallSite(user); cs.isCall()) {
+      if (cs.getCalledFunction() == func) {
+        callers.push_back(llvm::cast<llvm::CallInst>(user));
       }
     }
   }
@@ -1380,15 +1383,10 @@ void MoveFunctionIntoModule(llvm::Function *func, llvm::Module *dest_module) {
         }
       }
 
-      if (auto ci = llvm::dyn_cast<llvm::CallInst>(&inst); ci) {
-        if (auto callee = ci->getCalledFunction();
-            callee && callee->getParent() != dest_module) {
-          ci->setCalledOperand(DeclareFunctionInModule(callee, dest_module));
-        }
-      } else if (auto ii = llvm::dyn_cast<llvm::InvokeInst>(&inst); ii) {
-        if (auto callee = ii->getCalledFunction();
+      if (auto cs = compat::llvm::CallSite(&inst)) {
+        if (auto callee = cs.getCalledFunction();
             callee && callee->getParent() != dest_module) {
-          ii->setCalledOperand(DeclareFunctionInModule(callee, dest_module));
+          cs.setCalledFunction(DeclareFunctionInModule(callee, dest_module));
         }
       }
     }