[llvm] [WebAssembly] Fix missed optimization in 50142 (PR #144741)

[Luke Lau via llvm-commits]

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@@ -3248,6 +3248,37 @@ static SDValue performSETCCCombine(SDNode *N,
   ISD::CondCode Cond = cast<CondCodeSDNode>(N->getOperand(2))->get();
   SDLoc DL(N);
   EVT VT = N->getValueType(0);
+  //  N           LHS     LhsL        LhsLL    LhsLR   InnerCond RHS Cond
+  // setcc (iN (bitcast (setcc vNi1 (vNiY X), <vNiY 0>, eq)),     0, eq
+  // => all_true (vNi1 X)
+  if (DCI.isBeforeLegalize() && VT.isScalarInteger() && (Cond == ISD::SETEQ) &&
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lukel97 wrote:

Looking at this combine its quite similar to the one below, I wonder if it could be generalized?

i.e. we could rely on the combine below to do the first half, and then we would add a combine for

`wasm_anytrue (sext/zext (setcc x, 0, eq)) -> not (wasm_alltrue x)`

and

`wasm_anytrue (sext/zext (setcc x, 0, ne)) -> wasm_alltrue x`

I think you'd have then do the combine on `ISD::INTRINSIC_WO_CHAIN`. But this is just an idea, it might turn out to be harder :)

https://github.com/llvm/llvm-project/pull/144741