This allows SDNodes to be validated against their expected type profiles
and reduces the number of changes required to add a new node.

The validation functionality has detected several issues, see
`PPCSelectionDAGInfo::verifyTargetNode()`.

Most of the nodes have a description in `*.td` files and were
successfully "imported". Those that don't have a description are listed
in the enum in `PPCSelectionDAGInfo.td`. These nodes are not validated.

Part of #119709.

Pull Request: https://github.com/llvm/llvm-project/pull/168108

The current implementation assumes ConstantInt return values are scalar,
which is not true when use-constant-int-for-fixed-length-splat is
enabled.

It is common to have ABI requirements for illegal types: For example,
two i64 argument parts that originally came from an fp128 argument may
have a different call ABI than ones that came from a i128 argument.

The current calling convention lowering does not provide access to this
information, so backends come up with various hacks to support it (like
additional pre-analysis cached in CCState, or bypassing the default
logic entirely).

This PR adds the original IR type to InputArg/OutputArg and passes it
down to CCAssignFn. It is not actually used anywhere yet, this just does
the mechanical changes to thread through the new argument.

This focuses on the common interfaces and tablegen. More changes
are needed to individual targets.

Identified with misc-include-cleaner.

This is a preparation for changing the data structure of MBBMap.

This iteration drops hunks where the loop body adds more elements.

This reverts commit 3614f65a7ba9d925010e3316a1d93bcebc632178.

fixupImmediateBr seems to resize ImmBranches.