[llvm] [AMDGPU] Add register pressure guard on LLVM-IR level to prevent harmful optimizations (PR #171267)

[via llvm-commits]

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+//===- AMDGPURegPressureGuard.h - Reg Pressure Guard -----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Guards transformations by measuring VGPR register pressure using the
+/// AMDGPURegPressureEstimator before and after applying a pass. If the
+/// pressure increases beyond a configurable threshold, the transformation
+/// is reverted to prevent potential register spilling.
+///
+//===----------------------------------------------------------------------====//
+
+#ifndef LLVM_LIB_TARGET_AMDGPU_AMDGPUREGPRESSUREGUARD_H
+#define LLVM_LIB_TARGET_AMDGPU_AMDGPUREGPRESSUREGUARD_H
+
+#include "llvm/IR/PassManager.h"
+#include "llvm/Pass.h"
+
+namespace llvm {
+
+class DominatorTree;
+class PostDominatorTree;
+class UniformityInfoAnalysis;
+
+class Function;
+
+struct AMDGPURegPressureGuardConfig {
+  unsigned MaxPercentIncrease = 20;
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tianhbai wrote:

Thanks, updated.

https://github.com/llvm/llvm-project/pull/171267