[PATCH] D92161: [GlobalISel] Remove duplicates from possible mappings

[Gabriel Hjort Åkerlund via Phabricator via llvm-commits]

ehjogab created this revision.
ehjogab added reviewers: dsanders, arsenm, qcolombet, ab, bjope, rovka.
Herald added a subscriber: hiraditya.
Herald added a project: LLVM.
ehjogab requested review of this revision.
Herald added a subscriber: wdng.

Some targets will in getInstrAlternativeMappings() will return a list
that contains the mapping returned by getInstrMapping(), thereby causing
duplicates. This patch removes such duplicates, which reduces the amount
of work that needs to be done when selecting register banks.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D92161

Files:
  llvm/include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h
  llvm/lib/CodeGen/GlobalISel/RegisterBankInfo.cpp


Index: llvm/lib/CodeGen/GlobalISel/RegisterBankInfo.cpp
===================================================================
--- llvm/lib/CodeGen/GlobalISel/RegisterBankInfo.cpp
+++ llvm/lib/CodeGen/GlobalISel/RegisterBankInfo.cpp
@@ -421,8 +421,19 @@
 
   // Then the alternative mapping, if any.
   InstructionMappings AltMappings = getInstrAlternativeMappings(MI);
-  for (const InstructionMapping *AltMapping : AltMappings)
-    PossibleMappings.push_back(AltMapping);
+  for (const InstructionMapping *AltMapping : AltMappings) {
+    // Check that we don't already have such a mapping.
+    bool AlreadyExists = false;
+    for (const InstructionMapping *Mapping : PossibleMappings) {
+      if (AltMapping->isCompatibleMapping(*Mapping)) {
+        AlreadyExists = true;
+        break;
+      }
+    }
+    if (!AlreadyExists) {
+      PossibleMappings.push_back(AltMapping);
+    }
+  }
 #ifndef NDEBUG
   for (const InstructionMapping *Mapping : PossibleMappings)
     assert(Mapping->verify(MI) && "Mapping is invalid");
Index: llvm/include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h
===================================================================
--- llvm/include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h
+++ llvm/include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h
@@ -220,6 +220,12 @@
           NumOperands(NumOperands) {
     }
 
+    /// Check if this mapping has the same \p OperandsMapping as another \p
+    /// Mapping.
+    bool isCompatibleMapping(const InstructionMapping &Mapping) const {
+      return this->OperandsMapping == Mapping.OperandsMapping;
+    }
+
     /// Default constructor.
     /// Use this constructor to express that the mapping is invalid.
     InstructionMapping() = default;


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