Add option to inline reused subexpressions

lifting-bits · Aug 26, 2022 · 36acd97 · 36acd97
1 parent 706c7da
commit 36acd97
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Showing 11 changed files with 40 additions and 8 deletions.
diff --git a/include/rellic/AST/Util.h b/include/rellic/AST/Util.h
@@ -89,6 +89,8 @@ struct DecompilationContext {
 
   size_t num_literal_structs = 0;
   size_t num_declared_structs = 0;
+
+  bool inline_reused_expressions = false;
 };
 
 template <typename TKey1, typename TKey2, typename TKey3, typename TValue>

diff --git a/include/rellic/Decompiler.h b/include/rellic/Decompiler.h
@@ -20,6 +20,7 @@ namespace rellic {
 struct DecompilationOptions {
   bool lower_switches = false;
   bool remove_phi_nodes = false;
+  bool inline_reused_expressions = false;
 };
 
 struct DecompilationResult {

diff --git a/lib/AST/IRToASTVisitor.cpp b/lib/AST/IRToASTVisitor.cpp
@@ -1311,7 +1311,7 @@ void IRToASTVisitor::VisitFunctionDecl(llvm::Function &func) {
       var = ast.CreateVarDecl(
           fdecl, expr_gen.GetQualType(alloca->getAllocatedType()), name);
       fdecl->addDecl(var);
-    } else if (inst.hasNUsesOrMore(2) ||
+    } else if ((inst.hasNUsesOrMore(2) && !dec_ctx.inline_reused_expressions) ||
                (inst.hasNUsesOrMore(1) && llvm::isa<llvm::CallInst>(inst)) ||
                llvm::isa<llvm::PHINode>(inst)) {
       if (!inst.getType()->isVoidTy()) {

diff --git a/lib/Decompiler.cpp b/lib/Decompiler.cpp
@@ -85,6 +85,7 @@ Result<DecompilationResult, DecompilationError> Decompile(
 
     ASTBuilder ast{*ast_unit};
     rellic::DecompilationContext dec_ctx;
+    dec_ctx.inline_reused_expressions = options.inline_reused_expressions;
     dec_ctx.marker_expr = ast.CreateAdd(ast.CreateFalse(), ast.CreateFalse());
     rellic::GenerateAST::run(*module, dec_ctx, *ast_unit);
     // TODO(surovic): Add llvm::Value* -> clang::Decl* map

diff --git a/scripts/decompile.py b/scripts/decompile.py
@@ -36,7 +36,7 @@ def run_cmd(cmd, timeout):
 def decompile(self, rellic, input, output, timeout):
     cmd = [rellic]
     cmd.extend(
-        ["--input", input, "--output", output]
+        ["--input", input, "--output", output, "--inline-expressions"]
     )
     p = run_cmd(cmd, timeout)
 

diff --git a/scripts/roundtrip.py b/scripts/roundtrip.py
@@ -52,7 +52,7 @@ def compile(self, clang, input, output, timeout, options=None):
 def decompile(self, rellic, input, output, timeout):
     cmd = [rellic]
     cmd.extend(
-        ["--input", input, "--output", output]
+        ["--input", input, "--output", output, "--inline-expressions"]
     )
     p = run_cmd(cmd, timeout)
 

diff --git a/tests/tools/decomp/diff_outputs.mk b/tests/tools/decomp/diff_outputs.mk
@@ -26,8 +26,8 @@ LL_DIFFS	:=	$(patsubst %.ll,%.diff,$(wildcard *.ll))
 	@echo ""
 	@echo "\`\`\`diff"
 	-@diff -u \
-		<( $(OLD_RELLIC) --input $< --output /dev/stdout ) \
-		<( $(NEW_RELLIC) --input $< --output /dev/stdout ) || true
+		<( $(OLD_RELLIC) --input $< --output /dev/stdout --inline-expressions) \
+		<( $(NEW_RELLIC) --input $< --output /dev/stdout --inline-expressions) || true
 	@echo "\`\`\`"
 	@echo ""
 
@@ -36,8 +36,8 @@ LL_DIFFS	:=	$(patsubst %.ll,%.diff,$(wildcard *.ll))
 	@echo ""
 	@echo "\`\`\`diff"
 	-@diff -u \
-		<( $(OLD_RELLIC) --input $< --output /dev/stdout ) \
-		<( $(NEW_RELLIC) --input $< --output /dev/stdout ) || true
+		<( $(OLD_RELLIC) --input $< --output /dev/stdout --inline-expressions) \
+		<( $(NEW_RELLIC) --input $< --output /dev/stdout --inline-expressions) || true
 	@echo "\`\`\`"
 	@echo ""
 

diff --git a/tools/decomp/Decomp.cpp b/tools/decomp/Decomp.cpp
@@ -30,6 +30,9 @@ DEFINE_bool(remove_phi_nodes, false,
             "Remove PHINodes from input bitcode before decompilation.");
 DEFINE_bool(lower_switch, false,
             "Remove SwitchInst by lowering them to branches.");
+DEFINE_bool(inline_expressions, false,
+            "Inline subexpressions used by multiple expressions instead of "
+            "creating auxiliary variables.");
 
 DECLARE_bool(version);
 
@@ -123,6 +126,7 @@ int main(int argc, char* argv[]) {
   rellic::DecompilationOptions opts{};
   opts.lower_switches = FLAGS_lower_switch;
   opts.remove_phi_nodes = FLAGS_remove_phi_nodes;
+  opts.inline_reused_expressions = FLAGS_inline_expressions;
 
   auto result{rellic::Decompile(std::move(module), opts)};
   if (result.Succeeded()) {

diff --git a/tools/xref/Xref.cpp b/tools/xref/Xref.cpp
@@ -265,8 +265,26 @@ static void Decompile(const httplib::Request& req, httplib::Response& res) {
     return;
   }
 
+  auto json{llvm::json::parse(req.body)};
+  if (!json) {
+    llvm::json::Object msg{{"message", "Invalid request: cannot parse."}};
+    SendJSON(res, msg);
+    res.status = 400;
+    return;
+  }
+
+  auto inline_exprs{json->getAsObject()->getBoolean("inline_exprs")};
+  if (!inline_exprs) {
+    llvm::json::Object msg{
+        {"message", "Invalid request: no key for inline_exprs."}};
+    SendJSON(res, msg);
+    res.status = 400;
+    return;
+  }
+
   try {
     session.DecompContext = std::make_unique<rellic::DecompilationContext>();
+    session.DecompContext->inline_reused_expressions = *inline_exprs;
     std::vector<std::string> args{"-Wno-pointer-to-int-cast",
                                   "-Wno-pointer-sign", "-target",
                                   session.Module->getTargetTriple()};

diff --git a/tools/xref/www/index.html b/tools/xref/www/index.html
@@ -75,6 +75,8 @@
                 :disabled="!module"><br>
             <input type="button" @click="useDefaultChain" value="Use default chain">
             <input type="button" @click="openAngha" value="Open AnghaBench file">
+            <input type="checkbox" v-model="inline_exprs" name="inline_exprs">
+            <label for="inline_exprs">Inline expressions</label>
         </header>
         <main>
             <splitpanes class="default-theme">

diff --git a/tools/xref/www/main.js b/tools/xref/www/main.js
@@ -90,6 +90,7 @@ const app = new Vue({
     el: '#app',
     components: { Splitpanes, Pane },
     data: {
+        inline_exprs: false,
         dragging: false,
         ast: null,
         module: null,
@@ -271,7 +272,10 @@ const app = new Vue({
                 try {
                     let res = await fetch("/action/decompile", {
                         credentials: "include",
-                        method: "POST"
+                        method: "POST",
+                        body: JSON.stringify({
+                            inline_exprs: this.inline_exprs
+                        })
                     })
                     if (res.status != 200) {
                         throw (await res.json()).message