tree d32f39842e8a1757e8b75f162e39924f83dcbc50
parent 65ed4fa57e6293f8e059a368ac52e2a57b1f78e4
author Shubham Sandeep Rastogi <srastogi22@apple.com> 1739398098 -0800
committer GitHub <noreply@github.com> 1739398098 -0800
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Add a pass to collect dropped var statistics for MIR (#126686)

This patch attempts to reland
https://github.com/llvm/llvm-project/pull/120780 while addressing the
issues that caused the patch to be reverted.

Namely:

1. The patch had included code from the llvm/Passes directory in the
llvm/CodeGen directory.

2. The patch increased the backend compile time by 2% due to adding a
very expensive include in MachineFunctionPass.h

The patch has been re-structured so that there is no dependency between
the llvm/Passes and llvm/CodeGen directory, by moving the base class,
`class DroppedVariableStats` to the llvm/IR directory.

The expensive include in MachineFunctionPass.h has been changed to
contain forward declarations instead of other header includes which was
pulling a ton of code into MachineFunctionPass.h and should resolve any
issues when it comes to compile time increase.