[PATCH] D86836: Support a list of CostPerUse values

[Christudasan Devadasan via Phabricator via llvm-commits]

cdevadas added inline comments.


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Comment at: llvm/lib/CodeGen/RegAllocGreedy.cpp:790
   // Try to evict interference from a cheaper alternative.
-  unsigned Cost = TRI->getCostPerUse(PhysReg);
+  unsigned Cost = RegCosts[PhysReg];
 
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madhur13490 wrote:
> There is an implicit upcast happening here from `uint8_t` to `unsigned`. This may lead to unexpected behavior on different platform, I'd recommend to be consistent unless absolutely necessary to use `unsigned`.
Will change such instances to uint8_t.


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Comment at: llvm/utils/TableGen/CodeGenRegisters.h:154
     unsigned EnumValue;
-    unsigned CostPerUse;
+    std::vector<int64_t> CostPerUse;
     bool CoveredBySubRegs;
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madhur13490 wrote:
> Is there any specific reason to use `int64_t` type for `CostPerUse`?
`getValueAsListOfInts` works only with int64_t type.


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Comment at: llvm/utils/TableGen/RegisterInfoEmitter.cpp:1460
+  std::vector<bool> InAllocClass;
+  RegCosts.insert(RegCosts.end(), NumRegCosts, 0);
+  InAllocClass.push_back(false);
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madhur13490 wrote:
> What is the purpose of this extra block of 0s at the beginning?
 It is for NoRegister which is the first entry in the generated register list


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D86836/new/

https://reviews.llvm.org/D86836