T367_letnoescape coaxes LLVM backend into producing invalid IR
The nightly armv7 job reveals that the LLVM backend produces invalid LLVM IR for the T367_letnoescape
testcase:
Compile failed (exit code 1) errors were:
[1 of 1] Compiling Main ( T367_letnoescape.hs, T367_letnoescape.o )
Entry block to function must not have predecessors!
label %c2T7
opt: /tmp/ghc53214_0/ghc_2.ll: error: input module is broken!
`opt' failed in phase `LLVM Optimiser'. (Exit code: 1)
*** unexpected failure for T367_letnoescape(threaded2)
The following ways are affected:
concurrent/should_run/T367_letnoescape.run T367_letnoescape [exit code non-0] (dyn)
concurrent/should_run/T367_letnoescape.run T367_letnoescape [exit code non-0] (hpc)
concurrent/should_run/T367_letnoescape.run T367_letnoescape [exit code non-0] (profasm)
concurrent/should_run/T367_letnoescape.run T367_letnoescape [exit code non-0] (profthreaded)
concurrent/should_run/T367_letnoescape.run T367_letnoescape [exit code non-0] (threaded2)