[llvm] [CalcSpillWeights] Simplify copy hint register collection. NFC. (PR #114236)

[Valery Pykhtin via llvm-commits]

================
@@ -287,29 +270,34 @@ float VirtRegAuxInfo::weightCalcHelper(LiveInterval &LI, SlotIndex *Start,
     if (!TII.isCopyInstr(*MI))
       continue;
     Register HintReg = copyHint(MI, LI.reg(), TRI, MRI);
-    if (!HintReg)
-      continue;
-    // Force HWeight onto the stack so that x86 doesn't add hidden precision,
-    // making the comparison incorrectly pass (i.e., 1 > 1 == true??).
-    stack_float_t HWeight = Hint[HintReg] += Weight;
-    if (HintReg.isVirtual() || MRI.isAllocatable(HintReg))
-      CopyHints.insert(CopyHint(HintReg, HWeight));
+    if (HintReg && (HintReg.isVirtual() || MRI.isAllocatable(HintReg)))
+      Hint[HintReg] += Weight;
   }
 
   // Pass all the sorted copy hints to mri.
-  if (ShouldUpdateLI && CopyHints.size()) {
+  if (ShouldUpdateLI && Hint.size()) {
     // Remove a generic hint if previously added by target.
     if (TargetHint.first == 0 && TargetHint.second)
       MRI.clearSimpleHint(LI.reg());
 
-    SmallSet<Register, 4> HintedRegs;
-    for (const auto &Hint : CopyHints) {
-      if (!HintedRegs.insert(Hint.Reg).second ||
-          (TargetHint.first != 0 && Hint.Reg == TargetHint.second))
-        // Don't add the same reg twice or the target-type hint again.
-        continue;
-      MRI.addRegAllocationHint(LI.reg(), Hint.Reg);
+    // Don't add the target-type hint again.
+    Register SkipReg = TargetHint.first != 0 ? TargetHint.second : Register();
+    SmallVector<std::pair<float, Register>, 4> FRegHints, VRegHints;
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vpykhtin wrote:

Thanks, I have no strong preference here, so I've returned the original CopyHint structure (except for const members) and made one sorted list.

https://github.com/llvm/llvm-project/pull/114236