InstCombine also should have taken care of this, but this
should be helpful when the fcmp based lowering strategy tries
to combine multiple tests.

Try to take advantage of the nan check behavior of fcmp.
x86_64 looks better, x86_32 looks worse.

Fixes #82659

There are some functions, such as `findRegisterDefOperandIdx` and  `findRegisterDefOperand`, that have too many default parameters. As a result, we have encountered some issues due to the lack of TRI  parameters, as shown in issue #82411.

Following @RKSimon 's suggestion, this patch refactors 9 functions, including `{reads, kills, defines, modifies}Register`,  `registerDefIsDead`, and `findRegister{UseOperandIdx, UseOperand, DefOperandIdx, DefOperand}`, adjusting the order of the TRI parameter and making it required. In addition, all the places that call these functions have also been updated correctly to ensure no additional impact.

After this, the caller of these functions should explicitly know whether to pass the `TargetRegisterInfo` or just a `nullptr`.

There are a number of more test combinations here that
can be done together and reduce the number of instructions.

https://reviews.llvm.org/D143191

This is recommit of 2e416cdd52, fixed to be accepatble by GCC.
The original commit message is below.

With this change bitwise operations are allowed for FPClassTest
enumeration, it must simplify using this type. Also some functions
changed to get argument of type FPClassTest instead of unsigned.

Differential Revision: https://reviews.llvm.org/D144241

This reverts commit e7613c1d9b259bdf2b0b06b4169d9a10dd553406.

GCC issues an error:

In file included from /home/buildbot/as-builder-4/lld-x86_64-ubuntu-fast/llvm-project/llvm/unittests/ADT/BitmaskEnumTest.cpp:9:
/home/buildbot/as-builder-4/lld-x86_64-ubuntu-fast/llvm-project/llvm/include/llvm/ADT/BitmaskEnum.h:66:22: error: explicit specialization of template<class E, class Enable> struct llvm::is_bitmask_enum outside its namespace must use a nested-name-specifier [-fpermissive]
   66 |   template <> struct is_bitmask_enum<Enum> : std::true_type {};                \
      |                      ^~~~~~~~~~~~~~~~~~~~~
/home/buildbot/as-builder-4/lld-x86_64-ubuntu-fast/llvm-project/llvm/unittests/ADT/BitmaskEnumTest.cpp:30:1: note: in expansion of macro LLVM_DECLARE_ENUM_AS_BITMASK
   30 | LLVM_DECLARE_ENUM_AS_BITMASK(Flags2, V4);
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is recommit of 2e416cdd52, reverted in 8555ab2fcd, because GCC
complains on extra qualification. The macro LLVM_DECLARE_ENUM_AS_BITMASK
does not specify llvm:: anymore, so the macro must occur in the namespace
llvm. Documentation updated accordingly. The original commit message is below.

With this change bitwise operations are allowed for FPClassTest
enumeration, it must simplify using this type. Also some functions
changed to get argument of type FPClassTest instead of unsigned.

Differential Revision: https://reviews.llvm.org/D144241

This reverts commit 2e416cdd52c1079b8c7cb1f7d7e557c889a4fb56.

Breaks the GCC build:

In file included from /home/npopov/repos/llvm-project/llvm/include/llvm/ADT/FloatingPointMode.h:18,
                 from /home/npopov/repos/llvm-project/llvm/include/llvm/ADT/APFloat.h:20,
                 from /home/npopov/repos/llvm-project/llvm/lib/Support/APFloat.cpp:14:
/home/npopov/repos/llvm-project/llvm/include/llvm/ADT/BitmaskEnum.h:66:22: error: extra qualification not allowed [-fpermissive]
   66 |   template <> struct llvm::is_bitmask_enum<Enum> : std::true_type {};          \
      |                      ^~~~
/home/npopov/repos/llvm-project/llvm/include/llvm/ADT/FloatingPointMode.h:223:1: note: in expansion of macro ‘LLVM_DECLARE_ENUM_AS_BITMASK’
  223 | LLVM_DECLARE_ENUM_AS_BITMASK(FPClassTest, /* LargestValue */ fcPosInf);
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/npopov/repos/llvm-project/llvm/include/llvm/ADT/BitmaskEnum.h:67:22: error: extra qualification not allowed [-fpermissive]
   67 |   template <> struct llvm::largest_bitmask_enum_bit<Enum> {                    \
      |                      ^~~~
/home/npopov/repos/llvm-project/llvm/include/llvm/ADT/FloatingPointMode.h:223:1: note: in expansion of macro ‘LLVM_DECLARE_ENUM_AS_BITMASK’
  223 | LLVM_DECLARE_ENUM_AS_BITMASK(FPClassTest, /* LargestValue */ fcPosInf);
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
[43/4396] Building CXX object lib/Supp...iles/LLVMSupport.dir/CommandLine.cpp.o

With this change bitwise operations are allowed for FPClassTest
enumeration, it must simplify using this type. Also some functions
changed to get argument of type FPClassTest instead of unsigned.

Differential Revision: https://reviews.llvm.org/D144241