[llvm] [AMDGPU] Added hot-block-rematerialize pass (PR #136631)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,1511 @@
+//===- AMDGPUHotBlockRematerialize.cpp - AMDGPU Hot BlockRematerialize ----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file
+/// \brief AMDGPU hot block Rematerialize
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arsenm wrote:

Can we do this in the IR? The complexity is about 100x higher to do this on MachineIR while dealing with LiveIntervals 

https://github.com/llvm/llvm-project/pull/136631