Silence clang warn (#305)

* Bring `ast_unit`, `ast_ctx`, `ast` into `dec_ctx` * Move `GetQualType` to `DecompilationContext` * Add type provider * Add type provider for `main` * Update copyright * Revert formatting change * Emit non-signed `char`s * Allow adding type providers from decomp API * Fix merge error * More merge errors * silence clang warning for arm * Recognize strings referenced without GEP * replace function if address is not taken * rename replacement function: Co-authored-by: Francesco Bertolaccini <[email protected]> Co-authored-by: William Tan <[email protected]> Co-authored-by: 2over12 <[email protected]>
lifting-bits · Oct 25, 2022 · d51bed7 · d51bed7
1 parent 59b4751
commit d51bed7
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Showing 3 changed files with 55 additions and 34 deletions.
diff --git a/lib/AST/IRToASTVisitor.cpp b/lib/AST/IRToASTVisitor.cpp
@@ -181,8 +181,42 @@ void ExprGen::VisitGlobalVar(llvm::GlobalVariable &gvar) {
   }
 }
 
+static bool IsGVarAString(llvm::GlobalVariable *gvar) {
+  if (!gvar->hasInitializer()) {
+    return false;
+  }
+
+  auto constant{gvar->getInitializer()};
+  // Check if constant can be considered a string literal
+  auto arr_type{llvm::dyn_cast<llvm::ArrayType>(constant->getType())};
+  if (!arr_type) {
+    return false;
+  }
+
+  auto elm_type{arr_type->getElementType()};
+  if (!elm_type->isIntegerTy(8U)) {
+    return false;
+  }
+
+  auto arr{llvm::dyn_cast<llvm::ConstantDataArray>(constant)};
+  if (!arr) {
+    return false;
+  }
+
+  auto init{arr->getAsString().str()};
+  if (init.find('\0') != init.size() - 1) {
+    return false;
+  }
+
+  return true;
+}
+
 clang::Expr *ExprGen::CreateConstantExpr(llvm::Constant *constant) {
   if (auto gvar = llvm::dyn_cast<llvm::GlobalVariable>(constant)) {
+    if (IsGVarAString(gvar)) {
+      auto arr{llvm::cast<llvm::ConstantDataArray>(gvar->getInitializer())};
+      return ast.CreateStrLit(arr->getAsString().str().c_str());
+    }
     VisitGlobalVar(*gvar);
   }
 
@@ -518,33 +552,7 @@ clang::Expr *ExprGen::visitGetElementPtrInst(llvm::GetElementPtrInst &inst) {
       return false;
     }
 
-    if (!gvar->hasInitializer()) {
-      return false;
-    }
-
-    auto constant{gvar->getInitializer()};
-    // Check if constant can be considered a string literal
-    auto arr_type{llvm::dyn_cast<llvm::ArrayType>(constant->getType())};
-    if (!arr_type) {
-      return false;
-    }
-
-    auto elm_type{arr_type->getElementType()};
-    if (!elm_type->isIntegerTy(8U)) {
-      return false;
-    }
-
-    auto arr{llvm::dyn_cast<llvm::ConstantDataArray>(constant)};
-    if (!arr) {
-      return false;
-    }
-
-    auto init{arr->getAsString().str()};
-    if (init.find('\0') != init.size() - 1) {
-      return false;
-    }
-
-    return true;
+    return IsGVarAString(gvar);
   };
 
   // Maybe we're inspecting a string reference

diff --git a/lib/BC/Util.cpp b/lib/BC/Util.cpp
@@ -306,7 +306,7 @@ void ConvertArrayArguments(llvm::Module &m) {
   std::unordered_map<llvm::Type *, llvm::Type *> conv_types;
   std::vector<unsigned> indices;
   indices.push_back(0);
-  std::vector<llvm::Function *> funcs_to_remove;
+  std::vector<std::pair<llvm::Function *, llvm::Function *>> funcs_to_remove;
   auto &ctx{m.getContext()};
   auto ConvertType = [&](llvm::Type *t) -> llvm::Type * {
     if (!t->isArrayTy()) {
@@ -364,7 +364,7 @@ void ConvertArrayArguments(llvm::Module &m) {
         ret->eraseFromParent();
       }
     }
-    funcs_to_remove.push_back(orig_func);
+    funcs_to_remove.push_back(std::make_pair(orig_func, new_func));
     return new_func;
   };
 
@@ -425,12 +425,19 @@ void ConvertArrayArguments(llvm::Module &m) {
     }
   }
 
-  for (auto func : funcs_to_remove) {
+  for (auto [func_to_remove, replacement] : funcs_to_remove) {
     // TODO(frabert): Sometimes uses stick around which are not calls (e.g.
     // references in globals). How do we replace those? Cannot use
-    // `func->replaceAllUsesWith` because types don't match.
-    if (func->use_empty()) {
-      func->eraseFromParent();
+    // `func->replaceAllUsesWith` because types don't match
+    const llvm::User *user;
+    if (!func_to_remove->hasAddressTaken(&user, false, false, true, false)) {
+      auto orig_name = func_to_remove->getName().str();
+      func_to_remove->replaceAllUsesWith(replacement);
+      func_to_remove->eraseFromParent();
+      replacement->setName(orig_name);
+    } else {
+      DLOG(ERROR) << "Keeping around old array function: "
+                  << func_to_remove->getName().str();
     }
   }
 

diff --git a/lib/Decompiler.cpp b/lib/Decompiler.cpp
@@ -81,6 +81,12 @@ Result<DecompilationResult, DecompilationError> Decompile(
     std::vector<std::string> args{"-Wno-pointer-to-int-cast",
                                   "-Wno-pointer-sign", "-target",
                                   module->getTargetTriple()};
+    // Silence clang warning
+    // warning: unknown platform, assumming -mfloat-abi=soft
+    const auto& triple{llvm::Triple(module->getTargetTriple())};
+    if (triple.isARM()) {
+        args.push_back("-mfloat-abi=soft");
+    }
     auto ast_unit{clang::tooling::buildASTFromCodeWithArgs("", args, "out.c")};
     rellic::DecompilationContext dec_ctx(*ast_unit);
 
@@ -167,4 +173,4 @@ Result<DecompilationResult, DecompilationError> Decompile(
     return Result<DecompilationResult, DecompilationError>(std::move(error));
   }
 }
-}  // namespace rellic
+}  // namespace rellic