llvm-reduce: Fix assertion on blockaddress during function reduction

Just avoid crashing for now, we should be able to replace the blockaddresses
themselves.

BlockAddress::handleOperandChangeImpl a

llvm-reduce: Fix assertion on blockaddress during function reduction

Just avoid crashing for now, we should be able to replace the blockaddresses
themselves.

BlockAddress::handleOperandChangeImpl assumes it can cast to Function.
The verifier seems nonexistent and the langref isn't particularly explicit
on what's allowed as a blockaddress operand. As far as I can tell bugpoint
isn't doing anything to handle this.

Something low level is broken with BlockAddress handling,
demonstrated by reduce-functions-blockaddress-wrong-function.ll.
The BasicBlock destructor of the deleted function is triggering replacement
of blockaddresses for the kept function in some cases. I've only half debugged
this but it seems like blockaddress is handled too-specially compared to other
Constants. I have tentative patches to allow any constant to be a blockaddress
input, but having the verifier check if it's really a function/block.

https://reviews.llvm.org/D140909

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llvm-reduce: Fix producing invalid reductions on ifunc

[llvm-reduce] Move most debugging output behind --verbose

This should cut down on the visual noise when reducing. Still keep output when we run a pass or when we successfully reduce.

Notably, this

[llvm-reduce] Move most debugging output behind --verbose

This should cut down on the visual noise when reducing. Still keep output when we run a pass or when we successfully reduce.

Notably, this also suppresses redirecting the test output to stdout/stderr.

Reviewed By: regehr

Differential Revision: https://reviews.llvm.org/D131922

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[llvm-reduce] Try harder to not create invalid aliases

This was done by adding --abort-on-invalid-reduction to remove-function-bodies-used-in-globals.ll and fixing the fallout.

Aliases must have a

[llvm-reduce] Try harder to not create invalid aliases

This was done by adding --abort-on-invalid-reduction to remove-function-bodies-used-in-globals.ll and fixing the fallout.

Aliases must have a GlobalValue or ConstantExpr aliasee and the aliasee must be a definition if it's a GlobalValue.
Don't RAUW functions with null if there's an alias pointing to it, and similarly don't delete the body of a function.
Don't delete the entire body of a function when reducing blocks, preserve at least one block.

Also make debugging these sorts of things easier by dumping the module when --abort-on-invalid-reduction triggers.

Reviewed By: regehr

Differential Revision: https://reviews.llvm.org/D131505

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stop llvm-reduce from introducing undefs

Differential Revision: https://reviews.llvm.org/D128317