[llvm] [Codegen, X86] Add prefetch insertion based on Propeller profile (PR #166324)

[Haohai Wen via llvm-commits]

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@@ -81,7 +97,92 @@ bool InsertCodePrefetch::runOnMachineFunction(MachineFunction &MF) {
     V.erase(llvm::unique(V), V.end());
   }
   MF.setPrefetchTargets(PrefetchTargetsByBBID);
-  return false;
+  return true;
+}
+
+static bool
+insertPrefetchHints(MachineFunction &MF,
+                    const SmallVector<PrefetchHint> &PrefetchHints) {
+  bool PrefetchInserted = false;
+  bool IsELF = MF.getTarget().getTargetTriple().isOSBinFormatELF();
+  const Module *M = MF.getFunction().getParent();
+  DenseMap<UniqueBBID, SmallVector<PrefetchHint>> PrefetchHintsBySiteBBID;
+  for (const auto &H : PrefetchHints)
+    PrefetchHintsBySiteBBID[H.SiteID.BBID].push_back(H);
+  // Sort prefetch hints by their callsite index so we can insert them by one
+  // pass over the block's instructions.
+  for (auto &[SiteBBID, Hints] : PrefetchHintsBySiteBBID) {
+    llvm::sort(Hints, [](const PrefetchHint &H1, const PrefetchHint &H2) {
+      return H1.SiteID.CallsiteIndex < H2.SiteID.CallsiteIndex;
+    });
+  }
+  auto PtrTy =
+      PointerType::getUnqual(MF.getFunction().getParent()->getContext());
+  const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
+  for (auto &BB : MF) {
+    auto It = PrefetchHintsBySiteBBID.find(*BB.getBBID());
+    if (It == PrefetchHintsBySiteBBID.end())
+      continue;
+    const auto &BBHints = It->second;
+    unsigned NumCallsInBB = 0;
+    auto InstrIt = BB.begin();
+    for (auto HintIt = BBHints.begin(); HintIt != BBHints.end();) {
+      bool TargetFunctionDefined = false;
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HaohaiWen wrote:

Should recompute this TargetFunctionDefined  inside while loop as HintIt will be advanced in this while?

https://github.com/llvm/llvm-project/pull/166324