[llvm] [X86] Convert FP compares split by a nested logic op to FP logic (PR #226222)

[Simon Pilgrim via llvm-commits]

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@@ -52669,6 +52688,73 @@ static SDValue convertIntLogicToFPLogic(unsigned Opc, const SDLoc &DL, EVT VT,
   assert((Opc == ISD::OR || Opc == ISD::AND || Opc == ISD::XOR) &&
          "Unexpected bit opcode");
 
+  using namespace SDPatternMatch;
+  auto IsLegalFPType = [&](EVT FPVT) {
+    return (Subtarget.hasSSE1() && FPVT == MVT::f32) ||
+           (Subtarget.hasSSE2() && FPVT == MVT::f64) ||
+           (Subtarget.hasFP16() && FPVT == MVT::f16);
+  };
+  // Without AVX512VL, the v8f16 compares are not legal.
+  auto IsLegalFPCmpType = [&](EVT FPVT) {
+    return IsLegalFPType(FPVT) && (FPVT != MVT::f16 || Subtarget.hasVLX());
+  };
+
+  // Look through a single-use inner logic op to pair up two FP compares that
+  // it separates, e.g. by an integer compare. The recursive call only sees
+  // SETCC or converted operands, so this is limited to one level:
+  // logic (logic (setcc X), Y), (setcc Z) -->
+  // logic (logic (setcc X), (setcc Z)), Y
+  auto FPCmp = [](SDValue &Cmp) {
----------------
RKSimon wrote:

```suggestion
  auto FPCmp = [](SDValue Cmp) {
```

https://github.com/llvm/llvm-project/pull/226222