lli with -force-interpreter will cause assertion when having static class object in function

[llvmbot]

Bugzilla Link	1629
Resolution	FIXED
Resolved on	Dec 12, 2007 20:10
Version	trunk
OS	Linux
Reporter	LLVM Bugzilla Contributor

Extended Description

The following piece of code causes lli to crash when -force-interpreter is set.For Jit, it's okay.

class X {
unsigned v;
public:
X(int val) : v(val) {}
};

int main() {
static X a(0);
return 0;
}

Assertion info:
lli: /developer/home2/zsth/projects/commit/llvm/lib/Support/APInt.cpp:101: llvm::APInt::APInt(const llvm::APInt&): Assertion `BitWidth <= IntegerType::MAX_INT_BITS && "bitwidth too large"' failed.

The .ll file :
; ModuleID = ''
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
target triple = "i686-pc-linux-gnu"
%struct.X = type { i32 }
@​_ZGVZ4mainE1a = internal global i64 0, align 8 ; <i64*> [#uses=3]

define i32 @​main() {
entry:
%tmp2 = load i8* bitcast (i64* @​_ZGVZ4mainE1a to i8*), align 8 ; [#uses=1]
%tmp3 = icmp eq i8 %tmp2, 0 ; [#uses=1]
br i1 %tmp3, label %cond_true, label %UnifiedReturnBlock

cond_true: ; preds = %entry
%tmp5 = tail call i32 @​__cxa_guard_acquire( i64* @​_ZGVZ4mainE1a ) ; [#uses=1]
%tmp6 = icmp eq i32 %tmp5, 0 ; [#uses=1]
br i1 %tmp6, label %UnifiedReturnBlock, label %cond_true10

cond_true10: ; preds = %cond_true
tail call void @​__cxa_guard_release( i64* @​_ZGVZ4mainE1a )
ret i32 0

UnifiedReturnBlock: ; preds = %cond_true, %entry
ret i32 0
}

declare i32 @​__cxa_guard_acquire(i64*)

declare void @​__cxa_guard_release(i64*)

[llvmbot]

I debugged lli, and found that the assertion was caused right after the calling of function @​__cxa_guard_acquire().

Seems the lli interpreter converted the returned value of @​__cxa_guard_acquire into GenericValue, and then return it (see GenericValue Interpreter::callExternalFunction())

Seems the conversion is not safe which makes the GenericValue.IntVal uninitialized if the GenericValue is not used as APInt.

[llvmbot]

The APInt in a GenericValue is initialized with a bitwidth of 0 (purposefully), which is illegal. This is done to explicitly catch this kind of problem. What is the stack trace where this occurs?

[llvmbot]

In lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp,
GenericValue Interpreter::callExternalFunction():
Line 104:
GenericValue Result = GenericValue(Fn(const_cast<FunctionType*>(F->getFunctionType()), ArgVals));

APInt Result.IntVal's BitWidth is bigger than MAX bitwidth. I don't know how can this APInt object be constructed.

Line 106:
return Result;

This will incur APInt copy operation, and cause APInt assertion.

[llvmbot]

It is probably not being constructed which is the problem. You may be dealing with garbage in the APInt member vars.

[llvmbot]

Fixed by:

http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20071210/056225.html
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20071210/056235.html

[llvmbot]

Could you please fix the testcase too? I get this on Darwin:

FAIL: /Volumes/MacOS9/gcc/llvm/test/ExecutionEngine/2007-12-11-APIntExFuncCall.ll for llvm/llvm-bugzilla-archive#1629
Failed with signal(SIGABRT) at line 1
while running: llvm-as < /Volumes/MacOS9/gcc/llvm/test/ExecutionEngine/2007-12-11-APIntExFuncCall.ll -o - | lli -force-interpreter
Assertion failed: (0 && "Can't call __cxa_guard_acquire on this platform"), function lle_X___cxa_guard_acquire, file ExternalFunctions.cpp, line 738.
0 lli 0x00461f29 _ZN40_GLOBAL__N_Signals.cpp_00000000_22A60A9E15PrintStackTraceEv + 45
1 lli 0x004622cf _ZN40_GLOBAL__N_Signals.cpp_00000000_22A60A9E13SignalHandlerEi + 323
2 libSystem.B.dylib 0x9638897b _sigtramp + 43
3 ??? 0xffffffff 0x0 + 4294967295
4 libSystem.B.dylib 0x96401782 raise + 26
5 libSystem.B.dylib 0x96410d3f abort + 73
6 libSystem.B.dylib 0x96402923 __assert_rtn + 101
7 lli 0x001297c0 lle_X_rand + 0
8 lli 0x0012db20 _ZN4llvm11Interpreter20callExternalFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE + 420
9 lli 0x001287e7 _ZN4llvm11Interpreter12callFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE + 317
10 lli 0x00128efa _ZN4llvm11Interpreter13visitCallSiteENS_8CallSiteE + 1276
11 lli 0x00134cf8 _ZN4llvm11Interpreter13visitCallInstERNS_8CallInstE + 42
12 lli 0x00134d12 _ZN4llvm11InstVisitorINS_11InterpreterEvE9visitCallERNS_8CallInstE + 24
13 lli 0x00135772 _ZN4llvm11InstVisitorINS_11InterpreterEvE5visitERNS_11InstructionE + 1286
14 lli 0x00129237 _ZN4llvm11Interpreter3runEv + 159
15 lli 0x0012e012 _ZN4llvm11Interpreter11runFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESa
make: *** [check-local] Error 1

[lattner]

Please just remove the testcase, thanks!

[llvmbot]

Removed.