[ARM] Generate vcmp instead of vcmpe

Authored by kristof.beyls on Oct 8 2019, 1:25 AM.


[ARM] Generate vcmp instead of vcmpe

Based on the discussion in
http://lists.llvm.org/pipermail/llvm-dev/2019-October/135574.html, the
conclusion was reached that the ARM backend should produce vcmp instead
of vcmpe instructions by default, i.e. not be producing an Invalid
Operation exception when either arguments in a floating point compare
are quiet NaNs.

In the future, after constrained floating point intrinsics for floating
point compare have been introduced, vcmpe instructions probably should
be produced for those intrinsics - depending on the exact semantics
they'll be defined to have.

This patch logically consists of the following parts:

  • Revert http://llvm.org/viewvc/llvm-project?rev=294945&view=rev and http://llvm.org/viewvc/llvm-project?rev=294968&view=rev, which implemented fine-tuning for when to produce vcmpe (i.e. not do it for equality comparisons). The complexity introduced by those patches isn't needed anymore if we just always produce vcmp instead. Maybe these patches need to be reintroduced again once support is needed to map potential LLVM-IR constrained floating point compare intrinsics to the ARM instruction set.
  • Simply select vcmp, instead of vcmpe, see simple changes in lib/Target/ARM/ARMInstrVFP.td
  • Adapt lots of tests that tested for vcmpe (instead of vcmp). For all of these test, the intent of what is tested for isn't related to whether the vcmp should produce an Invalid Operation exception or not.

Fixes PR43374.

Differential Revision: https://reviews.llvm.org/D68463

llvm-svn: 374025


kristof.beylsOct 8 2019, 1:25 AM
Differential Revision
D68463: [ARM] Generate vcmp instead of vcmpe
rGc9ddda840526: [Tools] Mark output of tools as text if it is text