[LLVMdev] Fwd: [Bug 84232] PHINode containing itself causes segfault in LLVM when compiling Blender OpenCL kernel with R600 backend

[Виталий Филиппов]

Comment # 2 on bug 84232 from Vitaliy Filippov
Created attachment 107527 [details]
Attempt to reduce testcase using bugpoint

Tried to reduce the case using bugpoint:

PATH=/usr/lib/llvm-3.5/bin/:$PATH bugpoint-3.5 kernel.ll --llc-safe  
--tool-args
-- -march=r600 -mcpu=oland

The result leads to other crash, maybe it's also a bug, but it's definitely
another bug:

llc-3.5 -march=r600 -mcpu=oland bugpoint-reduced-simplified.ll

Which leads to a segfault on a non-assert build and to the following  
message on
a release+asserts build:

Unhandled loop condition!
UNREACHABLE executed at
/var/home/vitali/setup/llvm-toolchain-3.5-3.5/lib/Target/R600/SIAnnotateControlFlow.cpp:259!

This is probably related to bugpoint replacing the branch conditions with
constants, which makes conditional branches effectively unconditional :)  
and
SIAnnotateControlFlow::handleLoopCondition also doesn't handle this case.

Looks like an easy to fix problem?
-- 
With best regards,
   Vitaliy Filippov
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