[llvm] [AArch64] Add flag to control unrolling for small multi-exit loops (PR #131998)

[David Sherwood via llvm-commits]

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@@ -4375,6 +4380,87 @@ getFalkorUnrollingPreferences(Loop *L, ScalarEvolution &SE,
   }
 }
 
+static bool shouldUnrollLoopWithInstruction(Instruction &I,
+                                            AArch64TTIImpl &TTI) {
+  // Don't unroll vectorised loop.
+  if (I.getType()->isVectorTy())
+    return false;
+
+  if (isa<CallBase>(I)) {
+    if (isa<CallInst>(I) || isa<InvokeInst>(I))
+      if (const Function *F = cast<CallBase>(I).getCalledFunction())
+        if (!TTI.isLoweredToCall(F))
+          return true;
+    return false;
+  }
+
+  return true;
+}
+
+static unsigned getLoopSize(Loop *L, AArch64TTIImpl &TTI,
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david-arm wrote:

I've renamed this to `isLoopSizeWithinBudget` so that it returns a boolean instead, and passes the final size in an optional argument. I've also added some comments to the function. Hope this is better!

https://github.com/llvm/llvm-project/pull/131998