[llvm] Adding Matching and Inference Functionality to Propeller-PR2 (PR #162963)

[Rahman Lavaee via llvm-commits]

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@@ -0,0 +1,118 @@
+//===- llvm/CodeGen/MachineBlockHashInfo.h ----------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Compute the hashes of basic blocks.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_MACHINEBLOCKHASHINFO_H
+#define LLVM_CODEGEN_MACHINEBLOCKHASHINFO_H
+
+#include "llvm/CodeGen/MachineFunctionPass.h"
+
+namespace llvm {
+
+/// An object wrapping several components of a basic block hash. The combined
+/// (blended) hash is represented and stored as one uint64_t, while individual
+/// components are of smaller size (e.g., uint16_t or uint8_t).
+struct BlendedBlockHash {
+private:
+  static uint64_t combineHashes(uint16_t Hash1, uint16_t Hash2, uint16_t Hash3,
+                                uint16_t Hash4) {
+    uint64_t Hash = 0;
+
+    Hash |= uint64_t(Hash4);
+    Hash <<= 16;
+
+    Hash |= uint64_t(Hash3);
+    Hash <<= 16;
+
+    Hash |= uint64_t(Hash2);
+    Hash <<= 16;
+
+    Hash |= uint64_t(Hash1);
+
+    return Hash;
+  }
+
+  static void parseHashes(uint64_t Hash, uint16_t &Hash1, uint16_t &Hash2,
+                          uint16_t &Hash3, uint16_t &Hash4) {
+    Hash1 = Hash & 0xffff;
----------------
rlavaee wrote:

Instead of this shifting, define static variables `OffsetMask = 0xffff`, `OpcodeHashMask = 0xffff << 16`, etc.

And then simply do `Offset = Hash & OffsetMask`, `OpcodeHash = Hash & OpcodeHashMask`, etc. 

This will also make it easier to change the number of bits used for each hash later if needed.

https://github.com/llvm/llvm-project/pull/162963