Decompile of Binary Giving Strange Output

[cmpdylib.zip](https://github.com/avast/retdec/files/3142839/cmpdylib.zip)
^
This executable came from the Mac, it's a command from /usr/bin/cmpdylib.

When I decompiled it, it seemed to be successful:

```
Users-MBP:bin user$ python3 retdec-decompiler.py /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib
##### Checking if file is a Mach-O Universal static library...

##### Checking if file is an archive...
RUN: /Users/user/Downloads/retdec/bin/retdec-ar-extractor /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib --arch-magic
Not an archive, going to the next step.

##### Gathering file information...
RUN: /Users/user/Downloads/retdec/bin/retdec-fileinfo -c /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib.json --similarity /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib --no-hashes=all --crypto /Users/user/Downloads/retdec/bin/../share/retdec/support/generic/yara_patterns/signsrch/signsrch.yara --crypto /Users/user/Downloads/retdec/bin/../share/retdec/support/generic/yara_patterns/signsrch/signsrch.yarac --max-memory-half-ram
Input file : /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib
File format : Mach-O
File class : 64-bit
File type : Executable file
Architecture : x86-64
Endianness : Little endian
Entry point address : 0x100000f73
Entry point offset : 0xf73
Entry point section name : __text
Entry point section index: 0
Bytes on entry point : 554889e58d47ff488d5608488d3d2900000031c989c6e800000000ff257c0000004c8d1d6d0000004153ff255d0000009068
Detected tool : gc (compiler), 29 from 160 significant nibbles (18.125%)

##### Trying to unpack /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib into /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib-unpacked.tmp by using generic unpacker...
RUN: /Users/user/Downloads/retdec/bin/retdec-unpacker /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib -o /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib-unpacked.tmp --max-memory-half-ram
No matching plugins found for 'gc'
##### Unpacking by using generic unpacker: nothing to do
##### 'upx' not available: nothing to do

##### Decompiling /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib into /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib.bc...
RUN: /Users/user/Downloads/retdec/bin/retdec-bin2llvmir -provider-init -decoder -verify -x87-fpu -main-detection -idioms-libgcc -inst-opt -cond-branch-opt -syscalls -stack -constants -param-return -local-vars -inst-opt -simple-types -generate-dsm -remove-asm-instrs -class-hierarchy -select-fncs -unreachable-funcs -inst-opt -x86-addr-spaces -value-protect -instcombine -tbaa -targetlibinfo -basicaa -domtree -simplifycfg -domtree -early-cse -lower-expect -targetlibinfo -tbaa -basicaa -globalopt -mem2reg -instcombine -simplifycfg -basiccg -domtree -early-cse -lazy-value-info -jump-threading -correlated-propagation -simplifycfg -instcombine -simplifycfg -reassociate -domtree -loops -loop-simplify -lcssa -loop-rotate -licm -lcssa -instcombine -scalar-evolution -loop-simplifycfg -loop-simplify -aa -loop-accesses -loop-load-elim -lcssa -indvars -loop-idiom -loop-deletion -memdep -gvn -memdep -sccp -instcombine -lazy-value-info -jump-threading -correlated-propagation -domtree -memdep -dse -dce -bdce -adce -die -simplifycfg -instcombine -strip-dead-prototypes -globaldce -constmerge -constprop -instnamer -domtree -instcombine -instcombine -tbaa -targetlibinfo -basicaa -domtree -simplifycfg -domtree -early-cse -lower-expect -targetlibinfo -tbaa -basicaa -globalopt -mem2reg -instcombine -simplifycfg -basiccg -domtree -early-cse -lazy-value-info -jump-threading -correlated-propagation -simplifycfg -instcombine -simplifycfg -reassociate -domtree -loops -loop-simplify -lcssa -loop-rotate -licm -lcssa -instcombine -scalar-evolution -loop-simplifycfg -loop-simplify -aa -loop-accesses -loop-load-elim -lcssa -indvars -loop-idiom -loop-deletion -memdep -gvn -memdep -sccp -instcombine -lazy-value-info -jump-threading -correlated-propagation -domtree -memdep -dse -dce -bdce -adce -die -simplifycfg -instcombine -strip-dead-prototypes -globaldce -constmerge -constprop -instnamer -domtree -instcombine -inst-opt -simple-types -stack-ptr-op-remove -idioms -global-to-local -dead-global-assign -instcombine -inst-opt -idioms -phi2seq -value-protect -disable-inlining -disable-simplify-libcalls -config-path /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib.json -max-memory-half-ram -o /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib.bc
Running phase: Initialization ( 0.02s )
Running phase: LLVM ( 0.03s )
Running phase: Providers initialization ( 0.03s )
Running phase: Input binary to LLVM IR decoding ( 0.08s )
Running phase: LLVM ( 0.08s )
Running phase: x87 fpu register analysis ( 0.08s )
Running phase: Main function identification optimization ( 0.08s )
Running phase: Libgcc idioms optimization ( 0.08s )
Running phase: LLVM instruction optimization ( 0.08s )
Running phase: Conditional branch optimization ( 0.08s )
Running phase: Syscalls optimization ( 0.08s )
Running phase: Stack optimization ( 0.08s )
Running phase: Constants optimization ( 0.08s )
Running phase: Function parameters and returns optimization ( 0.08s )
Running phase: Register localization optimization ( 0.08s )
Running phase: LLVM instruction optimization ( 0.08s )
Running phase: Simple types recovery optimization ( 0.08s )
Running phase: Disassembly generation ( 0.08s )
Running phase: Assembly mapping instruction removal ( 0.09s )
Running phase: C++ class hierarchy optimization ( 0.09s )
Running phase: Selected functions optimization ( 0.09s )
Running phase: Unreachable functions optimization ( 0.09s )
Running phase: LLVM instruction optimization ( 0.09s )
Running phase: x86 address spaces optimization ( 0.09s )
Running phase: Value protection optimization ( 0.09s )
Running phase: LLVM ( 0.09s )
Running phase: LLVM instruction optimization ( 0.10s )
Running phase: Simple types recovery optimization ( 0.10s )
Running phase: Stack pointer operations optimization ( 0.10s )
Running phase: Instruction idioms optimization ( 0.10s )
Running phase: Global to local optimization ( 0.10s )
Running phase: Dead global assign optimization ( 0.10s )
Running phase: LLVM ( 0.10s )
Running phase: LLVM instruction optimization ( 0.10s )
Running phase: Instruction idioms optimization ( 0.10s )
Running phase: Phi2Seq optimization ( 0.10s )
Running phase: Value protection optimization ( 0.10s )
Running phase: LLVM ( 0.10s )
Running phase: Bitcode Writer ( 0.10s )
Running phase: Assembly Writer ( 0.10s )
Running phase: Cleanup ( 0.10s )

##### Decompiling /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib.bc into /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib.c...
RUN: /Users/user/Downloads/retdec/bin/retdec-llvmir2hll -target-hll=c -var-renamer=readable -var-name-gen=fruit -var-name-gen-prefix= -call-info-obtainer=optim -arithm-expr-evaluator=c -validate-module -o /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib.c /Users/user/Downloads/retdec_output/cmpdylib/cmpdylib.bc -enable-debug -emit-debug-comments -config-path=/Users/user/Downloads/retdec_output/cmpdylib/cmpdylib.json -max-memory-half-ram
Running phase: initialization ( 0.04s )
-> creating the used HLL writer [c] ( 0.04s )
-> creating the used alias analysis [simple] ( 0.04s )
-> creating the used call info obtainer [optim] ( 0.04s )
-> creating the used evaluator of arithmetical expressions [c] ( 0.04s )
-> creating the used variable names generator [fruit] ( 0.04s )
-> creating the used variable renamer [readable] ( 0.04s )
-> creating the used semantics [libc,gcc-general,win-api] ( 0.04s )
-> loading the input config ( 0.04s )
Running phase: conversion of LLVM IR into BIR ( 0.04s )
-> converting global variables ( 0.05s )
-> converting function main ( 0.05s )
Running phase: removing functions prefixed with [__decompiler_undefined_function_] ( 0.05s )
Running phase: removing functions from standard libraries ( 0.05s )
Running phase: removing code that is not reachable in a CFG ( 0.05s )
Running phase: signed/unsigned types fixing ( 0.05s )
Running phase: converting LLVM intrinsic functions to standard functions ( 0.05s )
Running phase: obtaining debug information ( 0.05s )
Running phase: alias analysis [simple] ( 0.05s )
Running phase: optimizations [normal] ( 0.05s )
-> running GotoStmtOptimizer ( 0.05s )
-> running RemoveUselessCastsOptimizer ( 0.05s )
-> running UnusedGlobalVarOptimizer ( 0.05s )
-> running DeadLocalAssignOptimizer ( 0.05s )
-> running SimpleCopyPropagationOptimizer ( 0.05s )
-> running CopyPropagationOptimizer ( 0.05s )
-> running AuxiliaryVariablesOptimizer ( 0.05s )
-> running SimplifyArithmExprOptimizer ( 0.05s )
-> running IfStructureOptimizer ( 0.05s )
-> running LoopLastContinueOptimizer ( 0.05s )
-> running PreWhileTrueLoopConvOptimizer ( 0.05s )
-> running WhileTrueToForLoopOptimizer ( 0.05s )
-> running WhileTrueToWhileCondOptimizer ( 0.05s )
-> running IfBeforeLoopOptimizer ( 0.05s )
-> running LLVMIntrinsicsOptimizer ( 0.05s )
-> running VoidReturnOptimizer ( 0.05s )
-> running BreakContinueReturnOptimizer ( 0.05s )
-> running BitShiftOptimizer ( 0.05s )
-> running DerefAddressOptimizer ( 0.05s )
-> running EmptyArrayToStringOptimizer ( 0.05s )
-> running BitOpToLogOpOptimizer ( 0.05s )
-> running SimplifyArithmExprOptimizer ( 0.05s )
-> running UnusedGlobalVarOptimizer ( 0.05s )
-> running DeadLocalAssignOptimizer ( 0.05s )
-> running SimpleCopyPropagationOptimizer ( 0.05s )
-> running CopyPropagationOptimizer ( 0.05s )
-> running SelfAssignOptimizer ( 0.05s )
-> running VarDefForLoopOptimizer ( 0.05s )
-> running VarDefStmtOptimizer ( 0.05s )
-> running EmptyStmtOptimizer ( 0.05s )
-> running GotoStmtOptimizer ( 0.05s )
-> running SimplifyArithmExprOptimizer ( 0.05s )
-> running DeadCodeOptimizer ( 0.05s )
-> running DerefToArrayIndexOptimizer ( 0.05s )
-> running IfToSwitchOptimizer ( 0.05s )
-> running CCastOptimizer ( 0.05s )
-> running CArrayArgOptimizer ( 0.05s )
Running phase: variable renaming [readable] ( 0.05s )
Running phase: converting constants to symbolic names ( 0.05s )
Running phase: module validation ( 0.05s )
-> running BreakOutsideLoopValidator ( 0.05s )
-> running NoGlobalVarDefValidator ( 0.05s )
-> running ReturnValidator ( 0.05s )
Running phase: emission of the target code [c] ( 0.05s )
Running phase: finalization ( 0.05s )
Running phase: cleanup ( 0.06s )

##### Done!

```

However, when I opened the .c file, I saw that there was barely any code in the main function:

```
//
// This file was generated by the Retargetable Decompiler
// Website: https://retdec.com
// Copyright (c) 2019 Retargetable Decompiler
//

#include

// ------------------------ Functions -------------------------

// Address range: 0x100000f73 - 0x100000f8e
int main(int argc, char ** argv) {
// 0x100000f73
return argc - 1;
}

// --------------------- Meta-Information ---------------------

// Detected compiler/packer: gc
// Detected functions: 1
// Decompilation date: 2019-05-03 23:32:35
```

If you man cmpdylib, the executable is supposed to do much more than that:

```
NAME
cmpdylib - compare two dynamic shared libraries for compatibility

SYNOPSIS
cmpdylib oldLibrary newLibrary

DESCRIPTION
cmpdylib compares two versions of a dynamic shared library to see if
they are compatible with each other...
```

Attaching the output of the decompile as well:
[cmpdylib_retdec_output.zip](https://github.com/avast/retdec/files/3142856/cmpdylib_retdec_output.zip)

Please help me check how come the output doesn't tally with what the binary is expected to do.

Reproduce the issue with the attached cmpdylib.zip using retdec-decompiler.py and compare the generated .c file with the attached RetDec output. Start by examining how the decompiler handles this Mach-O executable and reports detected functions; done means the output is consistent with the binary's observed behavior beyond the trivial main function.

Written by the indexing model from the issue text.