[llvm] [IR] Add intrinsics to represent complex multiply and divide operations (PR #68742)

[Simon Pilgrim via llvm-commits]

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@@ -31750,6 +31806,68 @@ bool X86TargetLowering::isInlineAsmTargetBranch(
   return Inst.equals_insensitive("call") || Inst.equals_insensitive("jmp");
 }
 
+bool X86TargetLowering::CustomLowerComplexMultiply(Type *FloatTy) const {
+  auto VecTy = cast<FixedVectorType>(FloatTy);
+  unsigned VecSize = VecTy->getNumElements() * VecTy->getScalarSizeInBits();
+  Type *ElementTy = VecTy->getElementType();
+  if (ElementTy->isHalfTy()) {
+    // All the half type need avx512fp16 enabled.
+    if (VecSize == 512)
+      // For 512-bt vector type, just avx512fp16 needed.
+      return Subtarget.hasFP16();
+    else
+      // 128-bit, 256-bit vector type are legal and other vector type can
+      // be widened or split. AVX512VL should be enabled.
+      return Subtarget.hasFP16() && Subtarget.hasVLX();
+  }
+  if (ElementTy->isFloatTy() || ElementTy->isDoubleTy()) {
+    if (VecSize == 512)
+      // For 512-bt vector type, they are legal or can be split.
+      return Subtarget.hasAVX512() || Subtarget.hasAnyFMA();
+    // 128-bit, 256-bit vector type are legal or and other type can
+    // be widened or split.
+    return Subtarget.hasAnyFMA() ||
+           (Subtarget.hasAVX512() && Subtarget.hasVLX());
+  }
+  return false;
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RKSimon wrote:

Can't we use the TLI isOperationLegal to do this? It seems to match the DAG setOperationAction setup earlier in the file.

https://github.com/llvm/llvm-project/pull/68742