[InstCombine] Optimize icmp-select-icmp

In special cases select instructions can be eliminated by
replacing them with a cheaper bitwise operation even when the
select result is used outside its home block. The instances implemented
are patterns like
    %x=icmp.eq
    %y=select %x,%r, null
    %z=icmp.eq|neq %y, null
    br %z,true, false
==> %x=icmp.ne
    %y=icmp.eq %r,null
    %z=or %x,%y
    br %z,true,false
The optimization is integrated into the instruction
combiner and performed only when all uses of the select result can
be replaced by the select operand proper. For this dominator information
is used and dominance is now a required analysis pass in the combiner.
The optimization itself is iterative. The critical step is to replace the
select result with the non-constant select operand. So the select becomes
local and the combiner iteratively works out simpler code pattern and
eventually eliminates the select.

rdar://17853760



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218721 91177308-0d34-0410-b5e6-96231b3b80d8
llvm/test/DebugInfo/X86/gmlt.test: Get rid of %llc_dwarf. It should not be used with -mtriple.

Also, remove object-emission. test/DebugInfo/X86 doesn't require it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218722 91177308-0d34-0410-b5e6-96231b3b80d8
llvm-cov/CoverageReport.cpp: Quick fix for msvcrt, since width specifier "z" is unavailable.

Note, mingw uses its own printf instead of msvcrt.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218723 91177308-0d34-0410-b5e6-96231b3b80d8
[x86] Teach the new vector shuffle lowering about VBROADCAST and
VPBROADCAST.

This has the somewhat expected pervasive impact. I don't know why
I forgot about this. Everything seems good with lots of significant
improvements in the tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218724 91177308-0d34-0410-b5e6-96231b3b80d8
[AVX512] Remove space before \t in AsmStrings.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218725 91177308-0d34-0410-b5e6-96231b3b80d8