phi-known.ll:test2 required deleting one manual check for a bitcast

Also strip trailing whitespace while we're touching everything.

Since D129288, callbr is allowed to have duplicate successors. This patch removes a limitation which prevents optimizations from actually producing such callbrs.

This is probably the riskiest of all the recent callbr changes, because code with incorrect assumptions might be lurking somewhere. I fixed the one case I encountered ahead of time in https://github.com/llvm/llvm-project/commit/8201e3ef5c84561260218bc041209611aac690e3.

Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D129997

Originally landed as
commit 08860f525a23 ("[Local] Allow creating callbr with duplicate successors")

Reverted in
commit 1cf6b93df168 ("Revert "[Local] Allow creating callbr with duplicate successors"")

This reverts commit 08860f525a2363ccd697ebb3ff59769e37b1be21.

Crashes during PPC64LE linux kernel builds as reported by @nathanchance.
https://reviews.llvm.org/D129997#3663632

Since D129288, callbr is allowed to have duplicate successors. This
patch removes a limitation which prevents optimizations from actually
producing such callbrs.

Differential Revision: https://reviews.llvm.org/D129997

Following some recent discussions, this changes the representation
of callbrs in IR. The current blockaddress arguments are replaced
with `!` label constraints that refer directly to callbr indirect
destinations:

    ; Before:
    %res = callbr i8* asm "", "=r,r,i"(i8* %x, i8* blockaddress(@test8, %foo))
    to label %asm.fallthrough [label %foo]
    ; After:
    %res = callbr i8* asm "", "=r,r,!i"(i8* %x)
    to label %asm.fallthrough [label %foo]

The benefit of this is that we can easily update the successors of
a callbr, without having to worry about also updating blockaddress
references. This should allow us to remove some limitations:

* Allow unrolling/peeling/rotation of callbr, or any other
  clone-based optimizations
  (https://github.com/llvm/llvm-project/issues/41834)
* Allow duplicate successors
  (https://github.com/llvm/llvm-project/issues/45248)

This is just the IR representation change though, I will follow up
with patches to remove limtations in various transformation passes
that are no longer needed.

Differential Revision: https://reviews.llvm.org/D129288

SplitBlockPredecessors currently asserts if one of the predecessor
terminators is a callbr. This limitation was originally necessary,
because just like with indirectbr, it was not possible to replace
successors of a callbr. However, this is no longer the case since
D67252. As the requirement nowadays is that callbr must reference
all blockaddrs directly in the call arguments, and these get
automatically updated when setSuccessor() is called, we no longer
need this limitation.

The only thing we need to do here is use replaceSuccessorWith()
instead of replaceUsesOfWith(), because only the former does the
necessary blockaddr updating magic.

I believe there's other similar limitations that can be removed,
e.g. related to critical edge splitting.

Differential Revision: https://reviews.llvm.org/D129205

In D115311, we're looking to modify clang to emit i constraints rather
than X constraints for callbr's indirect destinations. Prior to doing
so, update all of the existing tests in llvm/ to match.

Reviewed By: void, jyknight

Differential Revision: https://reviews.llvm.org/D115410

The reversion apparently deleted the test/Transforms directory.

Will be re-reverting again.

llvm-svn: 358552

As it's causing some bot failures (and per request from kbarton).

This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.

llvm-svn: 358546