Assertion NewParamInfo.size() == getNumParams() && "Parameter count mismatch!" failed.

[aytey]

I am using rellic at commit: 86280f6

The system I'm running this on is:

uname -a
Linux ubnt2204 5.15.0-101-generic #111-Ubuntu SMP Tue Mar 5 20:16:58 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 22.04.4 LTS
Release:        22.04
Codename:       jammy

Here's my example:

void a(void *b) { __asm__(""); }

Which I compile and try to decompile as follows:

${HOME}/lifting-bits-downloads/vcpkg_ubuntu-22.04_llvm-16_amd64/installed/x64-linux-rel/bin/clang -emit-llvm -c input.c -o input.bc -Wall -Wextra -Wpedantic -Werror -Wno-unused-parameter

${HOME}/rellic/rellic-build/install/usr/local/bin/rellic-decomp --input input.bc --output output.c

Note: I'm using the clang that gets pulled down by vcpkg when building rellic from source (so hopefully everything is compatible).

When I run this, I get the following error:

rellic-decomp: /__w/cxx-common/cxx-common/vcpkg/buildtrees/llvm-16/src/org-16.0.5-90a3d25b70.clean/clang/lib/AST/Decl.cpp:3489: void clang::FunctionDecl::setParams(clang::ASTContext&, llvm::ArrayRef<clang::ParmVarDecl*>): Assertion `NewParamInfo.size() == getNumParams() && "Parameter count mismatch!"' failed.

Here is how the backtrace looks in gdb:

#0  __pthread_kill_implementation (no_tid=0, signo=6, threadid=140737348173440) at ./nptl/pthread_kill.c:44
#1  __pthread_kill_internal (signo=6, threadid=140737348173440) at ./nptl/pthread_kill.c:78
#2  __GI___pthread_kill (threadid=140737348173440, signo=signo@entry=6) at ./nptl/pthread_kill.c:89
#3  0x00007ffff7a96476 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#4  0x00007ffff7a7c7f3 in __GI_abort () at ./stdlib/abort.c:79
#5  0x00007ffff7a7c71b in __assert_fail_base (fmt=0x7ffff7c31130 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n",
    assertion=0x55555b8c1378 "NewParamInfo.size() == getNumParams() && \"Parameter count mismatch!\"",
    file=0x55555b8be838 "/__w/cxx-common/cxx-common/vcpkg/buildtrees/llvm-16/src/org-16.0.5-90a3d25b70.clean/clang/lib/AST/Decl.cpp", line=3489, function=<optimized out>)
    at ./assert/assert.c:92
#6  0x00007ffff7a8de96 in __GI___assert_fail (assertion=0x55555b8c1378 "NewParamInfo.size() == getNumParams() && \"Parameter count mismatch!\"",
    file=0x55555b8be838 "/__w/cxx-common/cxx-common/vcpkg/buildtrees/llvm-16/src/org-16.0.5-90a3d25b70.clean/clang/lib/AST/Decl.cpp", line=3489,
    function=0x55555b8c1318 "void clang::FunctionDecl::setParams(clang::ASTContext&, llvm::ArrayRef<clang::ParmVarDecl*>)") at ./assert/assert.c:101
#7  0x000055555833398f in clang::FunctionDecl::setParams(clang::ASTContext&, llvm::ArrayRef<clang::ParmVarDecl*>) ()
#8  0x000055555622fe16 in clang::FunctionDecl::setParams (this=0x55555d0e9a28, NewParamInfo=...)
    at /home/avj/lifting-bits-downloads/vcpkg_ubuntu-22.04_llvm-16_amd64/installed/x64-linux-rel/include/clang/AST/Decl.h:2616
#9  0x000055555625a690 in rellic::IRToASTVisitor::VisitFunctionDecl (this=0x55555d00fe68, func=...) at /home/avj/rellic/lib/AST/IRToASTVisitor.cpp:1247
#10 0x000055555622ceaa in rellic::GenerateAST::run (this=0x55555d00fe68, module=..., MAM=...) at /home/avj/rellic/lib/AST/GenerateAST.cpp:545
#11 0x000055555624f415 in llvm::detail::PassModel<llvm::Module, rellic::GenerateAST, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (this=0x55555d00fe60, IR=..., AM=...) at /home/avj/lifting-bits-downloads/vcpkg_ubuntu-22.04_llvm-16_amd64/installed/x64-linux-rel/include/llvm/IR/PassManagerInternal.h:89
#12 0x00005555599d26fe in llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) ()
#13 0x000055555622d874 in rellic::GenerateAST::run (module=..., dec_ctx=...) at /home/avj/rellic/lib/AST/GenerateAST.cpp:653
#14 0x0000555555fe5002 in rellic::Decompile (module=std::unique_ptr<llvm::Module> = {...}, options=...) at /home/avj/rellic/lib/Decompiler.cpp:97
#15 0x0000555555fb5f91 in main (argc=1, argv=0x7fffffffe418) at /home/avj/rellic/tools/decomp/Decomp.cpp:125

[pgoodman]

It's possible that rellic doesn't properly understand inline assembly. Those are implemented via function calls in clang.

[aytey]

So the line where code hits the assertion is in the process of trying to handle the asm block, but it just falls over:

rellic/lib/AST/IRToASTVisitor.cpp

Lines 1223 to 1247 in 86280f6

	if (auto iasm = llvm::dyn_cast<llvm::InlineAsm>(&opnd)) {
	// TODO(frabert): We still need to find a way to embed the inline asm
	// into the function
	auto &decl{dec_ctx.value_decls[iasm]};
	if (decl) {
	return;
	}
	auto tudecl{dec_ctx.ast_ctx.getTranslationUnitDecl()};
	auto name{"asm_" +
	std::to_string(GetNumDecls<clang::FunctionDecl>(tudecl))};
	auto ftype{iasm->getFunctionType()};
	auto type{dec_ctx.GetQualType(ftype)};
	decl = ast.CreateFunctionDecl(tudecl, type, name);
	std::vector<clang::ParmVarDecl *> iasm_params;
	for (auto arg : ftype->params()) {
	auto arg_type{dec_ctx.GetQualType(arg)};
	auto name{"arg_" + std::to_string(iasm_params.size())};
	iasm_params.push_back(
	ast.CreateParamDecl(decl->getDeclContext(), arg_type, name));
	}
	auto fdecl{decl->getAsFunction()};
	fdecl->setParams(params);

[pgoodman]

Inline asm is tricky because Clang does some kind of translation of it into an internal LLVM-specific assembly dialect.