Does not Handle blockaddress constant

[rahulraghavendhra]

Hi,
I am interested in using this C-backend for my obfuscation project. The llvm-cbe breaks when I use Blockaddress constant. The below is the .ll file I used as the input to llvm-cbe.

; ModuleID = 'sample.c'
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

@.str = private unnamed_addr constant [6 x i8] c"good\0A\00", align 1

; Function Attrs: nounwind uwtable
define i32 @main() #0 {
entry:
%retval = alloca i32, align 4
%addr = alloca i8_, align 8
store i32 0, i32_ %retval
store i8* blockaddress(@main, %FOO), i8** %addr, align 8
%0 = load i8** %addr, align 8
br label %indirectgoto

FOO: ; preds = %indirectgoto
%call = call i32 (i8_, ...)_ @printf(i8* getelementptr inbounds ([6 x i8]* @.str, i32 0, i32 0))
ret i32 0

indirectgoto: ; preds = %entry
%indirect.goto.dest = phi i8* [ %0, %entry ]
indirectbr i8* %indirect.goto.dest, [label %FOO]
}

declare i32 @printf(i8*, ...) #1

attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }

!llvm.ident = !{!0}

!0 = metadata !{metadata !"clang version 3.5.0 (tags/RELEASE_350/final)"}

When I run llvm-cbe, the get the following error.

Unknown constant type: i8* blockaddress(@main, %FOO)
UNREACHABLE executed at CBackend.cpp:1205!
0 llvm-cbe 0x0000000001c7aff5 llvm::sys::PrintStackTrace(_IO_FILE*) + 38
1 llvm-cbe 0x0000000001c7b26d
2 llvm-cbe 0x0000000001c7abfd
3 libpthread.so.0 0x000000398240f710
4 libc.so.6 0x0000003981c32625 gsignal + 53
5 libc.so.6 0x0000003981c33e05 abort + 373
6 llvm-cbe 0x0000000001c6299b
7 llvm-cbe 0x0000000000ad394c
8 llvm-cbe 0x0000000000ad44de
9 llvm-cbe 0x0000000000ad458e
10 llvm-cbe 0x0000000000adfc75
11 llvm-cbe 0x0000000000ae17ff
12 llvm-cbe 0x0000000000ae0ee7
13 llvm-cbe 0x0000000000ad43c6
14 llvm-cbe 0x0000000000adb0d6
15 llvm-cbe 0x0000000000ad9ce1
16 llvm-cbe 0x0000000000acefc5
17 llvm-cbe 0x0000000001b71458 llvm::FPPassManager::runOnFunction(llvm::Function&) + 290
18 llvm-cbe 0x0000000001b715c8 llvm::FPPassManager::runOnModule(llvm::Module&) + 84
19 llvm-cbe 0x0000000001b7191c
20 llvm-cbe 0x0000000001b71fd0 llvm::legacy::PassManagerImpl::run(llvm::Module&) + 250
21 llvm-cbe 0x0000000001b721f1 llvm::legacy::PassManager::run(llvm::Module&) + 39
22 llvm-cbe 0x0000000000aba25c
23 llvm-cbe 0x0000000000ab93f5 main + 252
24 libc.so.6 0x0000003981c1ed5d __libc_start_main + 253
25 llvm-cbe 0x0000000000ab8d09
Stack dump:
0. Program arguments: llvm-cbe sample.ll -debug

1. Running pass 'Function Pass Manager' on module 'sample.ll'.
2. Running pass 'C backend' on function '@main'
   Aborted (core dumped)

Is it that llvm-cbe doesn't support Blockaddress constants?

[rtc-draper]

Yes, it looks like it doesn't have anything to handle blockaddress constants. Duly noted to add that when we can...thanks for the bug report!