[PATCH] D120121: [StableHashing] Hash vregs with multiple defs

[Jay Foad via Phabricator via llvm-commits]

foad added inline comments.


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Comment at: llvm/lib/CodeGen/MachineStableHash.cpp:69
+      for (auto &Def : MRI.def_instructions(MO.getReg()))
+        DefOpcodes.push_back(Def.getOpcode());
+      return hash_combine_range(DefOpcodes.begin(), DefOpcodes.end());
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arsenm wrote:
> If this only uses the opcode, won't it collide if you have multiple defs of the same register by the same opcode?
You'd get collisions anyway if different instructions with the same opcode define the register, but that was presumably by design, to make the hashing more stable somehow. I don't see how having multiple defs with the same opcode makes it any worse.


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  https://reviews.llvm.org/D120121/new/

https://reviews.llvm.org/D120121