[llvm] [EarlyCSE] Compare GEP instructions based on offset (PR #65875)

[Nikita Popov via llvm-commits]

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@@ -553,6 +553,77 @@ bool DenseMapInfo<CallValue>::isEqual(CallValue LHS, CallValue RHS) {
   return LHSI->isIdenticalTo(RHSI);
 }
 
+//===----------------------------------------------------------------------===//
+// GEPValue
+//===----------------------------------------------------------------------===//
+
+namespace {
+
+struct GEPValue {
+  Instruction *Inst;
+  APInt ConstantOffset;
+  bool HasConstantOffset;
+
+  GEPValue(Instruction *I) : Inst(I), HasConstantOffset(false) {
+      assert((isSentinel() || canHandle(I)) && "Inst can't be handled!");
+  }
+  GEPValue(Instruction *I, APInt ConstantOffset, bool HasConstantOffset)
+      : Inst(I), ConstantOffset(ConstantOffset),
+        HasConstantOffset(HasConstantOffset) {
+      assert((isSentinel() || canHandle(I)) && "Inst can't be handled!");
+  }
+
+  bool isSentinel() const {
+      return Inst == DenseMapInfo<Instruction *>::getEmptyKey() ||
+             Inst == DenseMapInfo<Instruction *>::getTombstoneKey();
+  }
+
+  static bool canHandle(Instruction *Inst) {
+      return isa<GetElementPtrInst>(Inst);
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nikic wrote:

The indents in these functions look wrong -- clang-format?

https://github.com/llvm/llvm-project/pull/65875