<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Issue</th>
<td>
<a href=https://github.com/llvm/llvm-project/issues/57792>57792</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>
Inconsistency between Interpreter and verifier when referencing a function in another module
</td>
</tr>
<tr>
<th>Labels</th>
<td>
</td>
</tr>
<tr>
<th>Assignees</th>
<td>
</td>
</tr>
<tr>
<th>Reporter</th>
<td>
Il-Capitano
</td>
</tr>
</table>
<pre>
Consider an execution engine having two modules:
```
; ModuleID = 'func1_module'
source_filename = "func1_module"
target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-w64-windows-gnu"
define i32 @func1() {
entry:
ret i32 42
}
```
and
```
; ModuleID = 'func2_module'
source_filename = "func2_module"
target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-w64-windows-gnu"
define i32 @func2() {
entry:
%0 = call i32 @func1()
ret i32 %0
}
declare i32 @func1()
```
When I try to execute `@func1` with an interpreter engine, the following error happens:
`LLVM ERROR: Tried to execute an unknown external function: func1`.
When using a JIT engine, everything works as expected, and the execution returns 42.
A workaround I found is to use the `Function` object from the module `func1_module` when creating the call `%0 = call i32 @func1()`, but with this method, if I run `verifyModule` on `func2_module`, it fails with the following message:
```
Referencing function in another module!
%0 = call i32 @func1()
; ModuleID = 'func2_module'
ptr @func1
; ModuleID = 'func1_module'
```
Also note that if I run an optimizer on `@func2`, the call to `@func1` will be deleted, probably because it is invalid IR, so I can't just ignore the verifier.
I've pasted a C++ file at the end of this comment that demonstrates the problem. Uncomment functions at the end of `main` to see the different results.
I tested on the following:
- Windows, with [msys2](https://github.com/msys2/MINGW-packages)'s `mingw-w64-x86_64-llvm` package (version 15.0.0)
- Ubuntu 20.04 using WSL2, with LLVM-15 installed from the official apt repository
In summary:
- Using a JIT engine and a function declaration (`use_decl_with_jit` function in the attached file): Everything works as expected
- Using an interpreter engine and a function declaration (`use_decl_with_interpreter`): Execution fails
- Using a JIT engine and a function from another module (`no_decl_with_jit`): Verification fails, execution succeeds
- Using an interpreter engine and a function from another module (`no_decl_with_interpreter`): Verification fails, execution succeeds
<details>
<summary>Code to reproduce the problem:</summary>
```
#include <memory>
#include <utility>
#include <string>
#include <llvm/ADT/Triple.h>
#include <llvm/Support/Host.h>
#include <llvm/IR/LLVMContext.h>
#include <llvm/Support/TargetSelect.h>
#include <llvm/MC/TargetRegistry.h>
#include <llvm/Target/TargetOptions.h>
#include <llvm/Target/TargetMachine.h>
#include <llvm/IR/IRBuilder.h>
#include <llvm/IR/Function.h>
#include <llvm/IR/Type.h>
#include <llvm/IR/Verifier.h>
#include <llvm/ExecutionEngine/ExecutionEngine.h>
#include <llvm/ExecutionEngine/GenericValue.h>
using ModulePtr = std::unique_ptr<llvm::Module>;
static ModulePtr create_module(
llvm::LLVMContext &context,
llvm::DataLayout const &data_layout,
std::string const &target_triple,
std::string const &name
)
{
auto result = std::make_unique<llvm::Module>(name, context);
result->setDataLayout(data_layout);
result->setTargetTriple(target_triple);
return result;
}
static std::pair<ModulePtr, llvm::Function *> make_func1(
llvm::LLVMContext &context,
llvm::DataLayout const &data_layout,
std::string const &target_triple
)
{
auto module = create_module(context, data_layout, target_triple, "func1_module");
auto const i32_type = llvm::Type::getInt32Ty(context);
auto const fn_type = llvm::FunctionType::get(i32_type, false);
auto const func1 = llvm::Function::Create(
fn_type,
llvm::Function::ExternalLinkage,
"func1",
*module
);
auto const entry_block = llvm::BasicBlock::Create(context, "entry", func1);
llvm::IRBuilder<> builder(context);
builder.SetInsertPoint(entry_block);
builder.CreateRet(llvm::ConstantInt::get(i32_type, 42));
llvm::dbgs() << "==== Verifying " << module->getName() << " ====\n";
llvm::verifyModule(*module, &llvm::dbgs());
return { std::move(module), func1 };
}
static std::pair<ModulePtr, llvm::Function *> make_func2(
llvm::LLVMContext &context,
llvm::DataLayout const &data_layout,
std::string const &target_triple,
llvm::Function *func1,
bool use_decl
)
{
auto module = create_module(context, data_layout, target_triple, "func2_module");
auto const i32_type = llvm::Type::getInt32Ty(context);
auto const fn_type = llvm::FunctionType::get(i32_type, false);
auto const func2 = llvm::Function::Create(
fn_type,
llvm::Function::ExternalLinkage,
"func2",
*module
);
auto const entry_block = llvm::BasicBlock::Create(context, "entry", func2);
llvm::IRBuilder<> builder(context);
builder.SetInsertPoint(entry_block);
if (use_decl)
{
auto const func1_decl = llvm::Function::Create(
func1->getFunctionType(),
llvm::Function::ExternalLinkage,
func1->getName(),
*module
);
auto const result = builder.CreateCall(func1_decl);
builder.CreateRet(result);
}
else
{
auto const result = builder.CreateCall(func1);
builder.CreateRet(result);
}
llvm::dbgs() << "==== Verifying " << module->getName() << " ====\n";
llvm::verifyModule(*module, &llvm::dbgs());
return { std::move(module), func2 };
}
static void use_decl_with_jit(
llvm::LLVMContext &context,
llvm::DataLayout const &data_layout,
std::string const &target_triple
)
{
auto func1_pair = make_func1(context, data_layout, target_triple);
auto &&func1_module = func1_pair.first;
auto &&func1 = func1_pair.second;
auto func2_pair = make_func2(context, data_layout, target_triple, func1, true);
auto &&func2_module = func2_pair.first;
auto &&func2 = func2_pair.second;
llvm::dbgs() << "========\n";
func1_module->print(llvm::dbgs(), nullptr);
llvm::dbgs() << "========\n";
func2_module->print(llvm::dbgs(), nullptr);
llvm::EngineBuilder builder(std::move(func1_module));
builder
.setEngineKind(llvm::EngineKind::JIT)
.setOptLevel(llvm::CodeGenOpt::None);
auto engine = std::unique_ptr<llvm::ExecutionEngine>(builder.create());
engine->addModule(std::move(func2_module));
auto func2_result = engine->runFunction(func2, {});
llvm::dbgs() << "========\n";
llvm::dbgs() << "Result: " << func2_result.IntVal << '\n';
}
static void use_decl_with_interpreter(
llvm::LLVMContext &context,
llvm::DataLayout const &data_layout,
std::string const &target_triple
)
{
auto func1_pair = make_func1(context, data_layout, target_triple);
auto &&func1_module = func1_pair.first;
auto &&func1 = func1_pair.second;
auto func2_pair = make_func2(context, data_layout, target_triple, func1, true);
auto &&func2_module = func2_pair.first;
auto &&func2 = func2_pair.second;
llvm::dbgs() << "========\n";
func1_module->print(llvm::dbgs(), nullptr);
llvm::dbgs() << "========\n";
func2_module->print(llvm::dbgs(), nullptr);
llvm::EngineBuilder builder(std::move(func1_module));
builder
.setEngineKind(llvm::EngineKind::Interpreter)
.setOptLevel(llvm::CodeGenOpt::None);
auto engine = std::unique_ptr<llvm::ExecutionEngine>(builder.create());
engine->addModule(std::move(func2_module));
auto func2_result = engine->runFunction(func2, {});
llvm::dbgs() << "========\n";
llvm::dbgs() << "Result: " << func2_result.IntVal << '\n';
}
static void no_decl_with_jit(
llvm::LLVMContext &context,
llvm::DataLayout const &data_layout,
std::string const &target_triple
)
{
auto func1_pair = make_func1(context, data_layout, target_triple);
auto &&func1_module = func1_pair.first;
auto &&func1 = func1_pair.second;
auto func2_pair = make_func2(context, data_layout, target_triple, func1, true);
auto &&func2_module = func2_pair.first;
auto &&func2 = func2_pair.second;
llvm::dbgs() << "========\n";
func1_module->print(llvm::dbgs(), nullptr);
llvm::dbgs() << "========\n";
func2_module->print(llvm::dbgs(), nullptr);
llvm::EngineBuilder builder(std::move(func1_module));
builder
.setEngineKind(llvm::EngineKind::JIT)
.setOptLevel(llvm::CodeGenOpt::None);
auto engine = std::unique_ptr<llvm::ExecutionEngine>(builder.create());
engine->addModule(std::move(func2_module));
auto func2_result = engine->runFunction(func2, {});
llvm::dbgs() << "========\n";
llvm::dbgs() << "Result: " << func2_result.IntVal << '\n';
}
static void no_decl_with_interpreter(
llvm::LLVMContext &context,
llvm::DataLayout const &data_layout,
std::string const &target_triple
)
{
auto func1_pair = make_func1(context, data_layout, target_triple);
auto &&func1_module = func1_pair.first;
auto &&func1 = func1_pair.second;
auto func2_pair = make_func2(context, data_layout, target_triple, func1, true);
auto &&func2_module = func2_pair.first;
auto &&func2 = func2_pair.second;
llvm::dbgs() << "========\n";
func1_module->print(llvm::dbgs(), nullptr);
llvm::dbgs() << "========\n";
func2_module->print(llvm::dbgs(), nullptr);
llvm::EngineBuilder builder(std::move(func1_module));
builder
.setEngineKind(llvm::EngineKind::Interpreter)
.setOptLevel(llvm::CodeGenOpt::None);
auto engine = std::unique_ptr<llvm::ExecutionEngine>(builder.create());
engine->addModule(std::move(func2_module));
auto func2_result = engine->runFunction(func2, {});
llvm::dbgs() << "========\n";
llvm::dbgs() << "Result: " << func2_result.IntVal << '\n';
}
int main(void)
{
llvm::LLVMContext context;
llvm::InitializeAllDisassemblers();
llvm::InitializeAllTargetInfos();
llvm::InitializeAllTargets();
llvm::InitializeAllTargetMCs();
llvm::InitializeAllAsmParsers();
llvm::InitializeAllAsmPrinters();
auto const target_triple = llvm::sys::getDefaultTargetTriple();
std::string target_error = "";
auto const target = llvm::TargetRegistry::lookupTarget(target_triple, target_error);
assert(target);
auto const target_machine = std::unique_ptr<llvm::TargetMachine>(
target->createTargetMachine(
target_triple,
"generic",
"",
llvm::TargetOptions(),
llvm::Reloc::Model::PIC_
)
);
assert(target_machine);
auto const data_layout = target_machine->createDataLayout();
// works as expected
// use_decl_with_jit(context, data_layout, target_triple);
// error: "LLVM ERROR: Tried to execute an unknown external function: func1"
use_decl_with_interpreter(context, data_layout, target_triple);
// works, but verfiyFunction fails for func2_module
// no_decl_with_jit(context, data_layout, target_triple);
// works, but verfiyFunction fails for func2_module
// no_decl_with_interpreter(context, data_layout, target_triple);
}
```
</details>
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJztW1tz4rgS_jXkRQUFJiHwkIeEJLPsSWamMtmZR0rYMtFESD6WnCz767db8kU2JsDO7FZqlypCfOlu9fVryVgLFa0vpkpqHrGUUEnY7yzMDFdwJJdcMvJEX7hcEvOqyEpFmWC6M7zs9K87_cvOqJ9_3Onwitxbktk16QzhLziPMxkO5o4RTh2hVlkasnnMBZN0xXLaoE4bOFpD0yUzJKKGCrpWmSmoWXcFirx2k-C8DwfDwH7h6aB-ikejU_vV5cVBPEamQTDuyjEejAoeuPcFLjfHNylPRKnp7-PRHAhf8Y_LSL3q7lJmJY_7jliM_uPDgHRO-9a4DgqekM75lSNh0qTr0p2EpDAS0p8Wgs6vWz1NZXRQBIIDIhD8myMQ7IpAJzjr2zFCKkRL7JqRQvpmrPKxQ0HTtvC3R85-f3tikszA1DUxKi9FMBmICgmjPnnl5gkrlUvD0gQUgcJ1tdoJpsQ8MRIrIdQrVi1LU5VCCScJk1i3YGAx-t3d13ty8_Dw6QGvP6acRf6gMEAmn6V6RUiAISQVBFVAaECGQp1eIdLqnmkclZJfZ4-eTuyFpWvzhLdeVfqsCdUgNGGhYRHeh3S2elfYA1ZlqdRQCD3fP5eWn6YqA44Z2In_uUa9M82sDFDptlATnKUW32EYEqdqZW-73EaqGtqgW1H_MGXUWLgDWpsC6PxdOYEkU7KAyrCxAUs1WTHzpKx1PAZV00yiKHAEj9f35aBKFqoElSqWCXSmXOhCoh_UFdOaLtk2GH5gMUuZDJG0iBgkC3hZgZyUFOU9OCzn98aWxKSVgMMaQ8OSS6EVAa0xstRUjoTcVInhK_4HmONcWNa3c18ZPsiMjfKBywtGIiZYnn9JqhZ0IdZwOaSYSOB9CCGXL1RwSLQHJAJVZiBTgrKGfM80kCylSl3W2bhyltaydQakL4wkVMM4UBTTTnAFH4KoS8Aem_KQwCp2KROq1QrwyBkbsRV0ZZNSw7SlRCUFW_XIb7IgLKKrG9LAzBXlNv_Bfs2cjhGPbWIYqC6dCaPryhIYCPUEf9bSrUyzLvnmkBa9YdOyc3a10msddM6uIVOejEns3CC4hc8SCLJFD1SFE0cV3N7PPn741k1o-Az5qzG1gnNt1YWBXi2a58AuxMsK9c9pIWPG4GONqTw46_V7fYviuV6_LTJpMhLA5dMcgr59uQtKPRHquoMzCKiGHibAyBIPVBzzkAO20QT9kijNjYKO4HtGEp2tVtTrEzDkBtBZFKNVxbkGQO0x1tGoD5k1x6tzVGr-nRs00K9QVIgaQ8MnVJFjYUwQa2_ews-6Qm1t4VDNPAm2nJwOJTZbXNrfD9bVdezJR5Vqwx35YF9tOYXUGw_bSKmCzsKQsaipxT7G76lOqw8OU6vAvmnEjKUd3pSXyoS6maqIYZVC7qWgTcj8YseEGwJs3Fb0NdmNOUQw5DIUWYSzpOkKAMTnqN0EfQU32-4C7NjCrw9WI7H1GdxeXj_C96OdmvWetojLab9kSaJSA0e_KG12USPo3mLhwuLEwAxkf-mPdr74BeA93Ml1Py0ZHtiSg-HrXSyOujz4lFgEPpDrHmocknMvJ8werjIuYHm2F3Ux-dmL-HGd7KfD16K_7SAuUeImn_w1rxwu4AOTMHj4lYqsxm2_Hdi7ucVnnHfA5EKbyNbNZSb5_zM2h_lIId9ezmdfIGh45cuC3mB46Amzk0FWzlHGBfGkkuUlKKDIKHSHgAottNewgLpzC6gQWzsy4KJq7lZVPlNpgqvEit6theZuLbQXBy7vCn8XM7nz0u4JzSz24Hyg7rwVfWZz58Et3gvGVjYgYGn2xHPpxEntAqlmpjIe-GpWb-dxpfKY2zpu2N7gw_VCbkh1o74kywNcmphQjplRBhxNqQwtCgmcCKc3xDqknBW_t1TYEeGi0eEkv5HVlaKkrgJpJlvbM5p6GOxYTkNYRswNwIsds7IcEccdgeiZNMPgce0rsU1cLNukFTGqSQVxxeCodEyFbqaLLxgN2iLWnU2tw_ygwyfXx49ULcJ1ETf5CvqOS5zNNrgKt1p_Nu5c5q4uL9YM2TTHPs-YL4QKnxtGXVHNwyu80TDLSwB8qGMfiFhN8jV-3XWVwLIv4RQFCmSRn22LZn6_9wUDr1lqPiuYZQG5p_MWFqfrg41tpQA-tjRUYhptC_6pzdA2n1ViosVSF4-F0BLrBvBd-XHzvjVWH9wpiFxgEKpg2I8WCRsyiC-kczaVVm6bK2uPBVBMEXYbk1Gbru0ACIXvQbh6QWmFqEkZUoLA-PeCZPAeQbJ1GN-EPOErsoVSghSro38UZIN_G8gG7wJkg3cJss0Q_6Mgy2NcAJdJXqY3-MHL8JauaekPjyoGFtlz6KylVw5t0wb9Xwx5faAKozfpWnKgmQYND3hz5nqXmlIBThxXHtoU09bW8qlrg7bC5gnDCtsdmb30-jkqHTtpsEcnfVE8IpuP_t5he9zR3lxG43zAZldtPbR3f9vsEKAGfPx1hRVfjdaLearNW3xNBs1An2iDw7XVTQOCwxp0MUkgJs12WBQ0LQr2syhoMmxYdHjt7SghPwBYiknq-kZ7xUyJzITAJyvbGtfP0Cf4UX02tHJPlfKW6jXTZqXXl7ntE4KC20NRiJNxQ_yPQ7h8bb3L9vzX2WOt1TrmT4m5Yy9MNNY5EfvAJNxz5x-VZNunKPlj732ehDUfttmHOkUnCMvevcV-NxDGhkZRibhtngx2eNKrTq99VfLTTJZ9P5do8RwQCiD3B1d3e7eWVkkP-ROnS7-h-ab0YP79lYqK5dwNcn542_B_kzi2j2P7OLaP_277mPlYcGwjxzbyVhvZ-KH92D2O3ePYPf673eO4-Dh2jcO6xnHtcewex-5x7B7Htcexi-zsIpDuxL6AHoyxk7TicnvnKLCs_bdQyQ2ngv_BLoW45ppqzVYLwdKilnZzuVfKZjJWh_IcSn8_3Z_jUq8-01QfYgiypLYpb_L4Ken6Za0RNH6x1WvdKX7Vv2YxhYA3XrxraNRsyblwt9Wo47ZnNTJwQ5XmCwu1N3DdNaHUc5YU78023_6b1oZttjKNv3yXTHt6Z-Xeyd0Ldmpv8TrQ8XHQScS6dxBUJ9_4OXzrWyqd4tWFpXsJtuXlBXu79XpT2_xN5d2_sT8woUJ3CJgISG4PP8-m8xqLD_1v-r_w7Pb3Q7x5i3V_na_yY-0t0tawus0n27ZJVARtP8j-pZlgXazLRgelP2WDXbWhcfLWjwE_QXXrsmIf2wtLY74uX41yW9FiqO9aL2xIaHnM9P70-nG_bdmT6zZqVHs9TtjFYDQaDkejcX9wEl0Mo8lwQk8MN4JdzCQmPqAdkyFuOzOvDHd-ertXcNtKsavM7U1MvX193oaWjZ19J1kqLt7YjJW_aY__ukmqcH8knHKtM9ySdXt2fj4JTp4uJqPz4SIcDVh_PKTx6WC8CKNJHNLJJBqenU6iE0EXTOiLztlV5-z6hF8E_SDoTwajAP71B71wFA5CGg8WownrB6eTzmmfwaRA9HDgnkqXJ-mF1WGRwaTktC_AG7q6CRjCl5KxQj6gxZNKL2aiO6UJN2DyiVX5wur7J4cPodQ">