[llvm] [TRE] Add tests for intrinsic accumulators (PR #74226)

[Nikita Popov via llvm-commits]

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@@ -369,12 +369,25 @@ static bool canTransformAccumulatorRecursion(Instruction *I, CallInst *CI) {
   if (!I->isAssociative() || !I->isCommutative())
     return false;
 
-  assert(I->getNumOperands() == 2 &&
-         "Associative/commutative operations should have 2 args!");
+  Value *LHS;
+  Value *RHS;
+  if (I->isBinaryOp()) {
+    LHS = I->getOperand(0);
+    RHS = I->getOperand(1);
+  } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
+    // Accumulators must have an identity.
+    if (!ConstantExpr::getIntrinsicIdentity(II->getIntrinsicID(), I->getType()))
+      return false;
+    // 0'th operand is the intrinsic function
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nikic wrote:

I'm quite confused here. The callee is the last operand, not the first one. How does this code work?

https://github.com/llvm/llvm-project/pull/74226