loop does not terminate in debug mode, but terminates in release mode.

[yuffon]

I am using SVF 2.7 on a simple IR file. In the debug version of SVF 2.7, I find a loop invocation in the following two functions. This loop invocation is a dead loop.

The function

LLVMModuleSet::getSVFType(const Type* T)

invokes collectTypeInfo(T); But collectTypeInfo(const Type* T) invokes collectSimpleTypeInfo(T);, which invokes getSVFType(ty); again.

This is a dead loop. Now I don't know why I do not meet this dead loop in release version of SVF.

[yuleisui]

This is a C++ recursion. It terminates once you have all the types collected here : https://github.com/SVF-tools/SVF/blob/6877950c4a1cb8a9d5ac026e57f28528b4440e7a/svf-llvm/lib/LLVMModule.cpp#L1202

Where do you find the dead loop? Could you give me a case?

[yuffon]

This is a C++ recursion. It terminates once you have all the types collected here :

https://github.com/SVF-tools/SVF/blob/6877950c4a1cb8a9d5ac026e57f28528b4440e7a/svf-llvm/lib/LLVMModule.cpp#L1202

Where do you find the dead loop? Could you give me a case?

Hi Yulei @yuleisui, I am debuging SVF 2.7 using llvm 14.0.6. The input program is

#include <malloc.h>
int main(){
    int i;
    int * p;
    p = (int *)malloc(32);
    if(*p){
        free(p);
    }
    *p = 4;
    return 0;
}

The IR file is

; ModuleID = 'cond-free.c'
source_filename = "cond-free.c"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

; Function Attrs: noinline nounwind optnone uwtable
define dso_local i32 @main() #0 {
entry:
  %retval = alloca i32, align 4
  %i = alloca i32, align 4
  %p = alloca i32*, align 8
  store i32 0, i32* %retval, align 4
  %call = call noalias i8* @malloc(i64 noundef 32) #2
  %0 = bitcast i8* %call to i32*
  store i32* %0, i32** %p, align 8
  %1 = load i32*, i32** %p, align 8
  %2 = load i32, i32* %1, align 4
  %tobool = icmp ne i32 %2, 0
  br i1 %tobool, label %if.then, label %if.end

if.then:                                          ; preds = %entry
  %3 = load i32*, i32** %p, align 8
  %4 = bitcast i32* %3 to i8*
  call void @free(i8* noundef %4) #2
  br label %if.end

if.end:                                           ; preds = %if.then, %entry
  %5 = load i32*, i32** %p, align 8
  store i32 4, i32* %5, align 4
  ret i32 0
}

; Function Attrs: nounwind
declare dso_local noalias i8* @malloc(i64 noundef) #1

; Function Attrs: nounwind
declare dso_local void @free(i8* noundef) #1

attributes #0 = { noinline nounwind optnone uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #1 = { nounwind "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #2 = { nounwind }

!llvm.module.flags = !{!0, !1, !2}
!llvm.ident = !{!3}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 7, !"uwtable", i32 1}
!2 = !{i32 7, !"frame-pointer", i32 2}
!3 = !{!"clang version 14.0.6 (https://github.com/llvm/llvm-project.git f28c006a5895fc0e329fe15fead81e37457cb1d1)"}

I have checked the detail of function getSVFType. Line 1139 of LLVMModule.cpp is LLVMType2SVFType[T] = svftype; Here T has an ID as IntegerTyID, svftype is new constructed pointer. Here LLVMType2SVFType.size() increases continuously. But the new inserted type info is not found as expected in the recursion exit.

I killed the process after waiting for three hours. The release version of SVF does not has such issue. The size of LLVMType2SVFType increases to 15 and stops.