llvm dev - Aug 2017 - Compile LLVM into LLVM IR with non-Xcode Clang

Hello,
I have a question about exit blocks : is it true that every loop's exit
block will contain only those comparisons that will lead to exit or to
continue execution in loop? I have tried many examples , after
optimizations it seems to be true, but does it have to be so?
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Yes, that’s right. Some LLVM terminology though: The blocks  you mention, are
called the “exiting blocks” of the loop, and the blocks outside the loop (that
are the targets of these exiting blocks) are called the exit blocks.

getExitingBlocks in LoopInfoImpl.h is the code you’re interested in.

By definition: one of the successor’s of the exiting block is an exit block, and
it should have another successor that’s a block within the loop (since we know
that an exiting block is *inside* a loop).


Anna
> On Jul 30, 2017, at 11:47 AM, Anastasiya Ruzhanskaya via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> 
> Hello,
> I have a question about exit blocks : is it true that every loop's exit
block will contain only those comparisons that will lead to exit or to continue
execution in loop? I have tried many examples , after optimizations it seems to
be true, but does it have to be so?
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Hi everyone,

I was able to compile LLVM to LLVM IR. However, when I read the results into my
program, I got "warning: ignoring debug info with an invalid version
(700000003)." I figured out it was because the Clang that comes with Xcode
uses an LLVM that's older than the LLVM I compiled from source, and
LLVM's IR isn't backwards compatible. I've tried using the following
CMake flags:
-DCMAKE_C_COMPILER=<path to clang built from source>
-DCMAKE_CXX_COMPILER=<path to clang++ built from source>

I also tried exporting the CC and CXX variables before invoking CMake. Both
attempts lead to the following message:

Scanning dependencies of target LLVMDemangle
[  0%] Building CXX object
lib/Demangle/CMakeFiles/LLVMDemangle.dir/ItaniumDemangle.cpp.o
[  0%] Linking CXX static library ../libLLVMDemangle.a
error:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/libtool:
file: CMakeFiles/LLVMDemangle.dir/ItaniumDemangle.cpp.o is not an object file
(not allowed in a library)
make[2]: *** [lib/libLLVMDemangle.a] Error 1
make[1]: *** [lib/Demangle/CMakeFiles/LLVMDemangle.dir/all] Error 2
make: *** [all] Error 2

How do I get CMake to use the correct Clang binary?

Thanks,
Mackenzie