Consider (x == -1) unlikely in BranchProbabilityInfo

This adds another heuristic to BPI, similar to the existing heuristic that
considers (x == 0) unlikely to be true. As suggested in the PACT'98 paper by
Deitrich, Cheng, and Hwu, -1 is often used to indicate an invalid index, and
equality comparisons with -1 are also unlikely to succeed. Local
experimentation supports this hypothesis: This yields a 1-2% speedup in the
test-suite sqlite benchmark on the PPC A2 core, with no significant
regressions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193855 91177308-0d34-0410-b5e6-96231b3b80d8
[ARM] Fix Tag_ABI_HardFP_use build attribute

Fix Tag_ABI_HardFP_use build attribute to handle single precision FP,
replace deprecated Tag_ABI_HardFP_use value of 3 with 0 and also add
some tests for Tag_ABI_VFP_args.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193856 91177308-0d34-0410-b5e6-96231b3b80d8
[ARM] Add Virtualization subtarget feature and more build attributes in this area

Add a Virtualization ARM subtarget feature along with adding proper build
attribute emission for Tag_Virtualization_use (encodes Virtualization and
TrustZone) and Tag_MPextension_use.

Also rework test/CodeGen/ARM/2010-10-19-mc-elf-objheader.ll testcase to
something that is more maintainable. This changes the focus of this
testcase away from testing CPU defaults (which is tested elsewhere), onto
specifically testing that attributes are encoded correctly.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193859 91177308-0d34-0410-b5e6-96231b3b80d8