[clang] [CIR] Upstream builtin lowering emitter & FAbs op (PR #151750)

[Andy Kaylor via cfe-commits]

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@@ -3199,4 +3199,22 @@ def CIR_ExpectOp : CIR_Op<"expect", [
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// Floating Point Ops
+//===----------------------------------------------------------------------===//
+
+class CIR_UnaryFPToFPBuiltinOp<string mnemonic, string llvmOpName>
+    : CIR_Op<mnemonic, [Pure, SameOperandsAndResultType]>
+{
+  let arguments = (ins CIR_AnyFloatOrVecOfFloatType:$src);
+  let results = (outs CIR_AnyFloatOrVecOfFloatType:$result);
+  let summary = "libc builtin equivalent ignoring "
+                "floating point exceptions and errno";
+  let assemblyFormat = "$src `:` type($src) attr-dict";
+
+  let llvmOp = llvmOpName;
+}
+
+def CIR_FAbsOp : CIR_UnaryFPToFPBuiltinOp<"fabs", "FAbsOp">;
----------------
andykaylor wrote:

I'd prefer to see a summary and description here. Something like:

```
  let summary = "Computes the floating-point absolute value";
  let description = [{
    `cir.fabs` computes the absolute value of a floating-point operand
    and returns a result of the same type, ignoring floating-point
    exceptions. It does not set `errno`.
  }];
```

https://github.com/llvm/llvm-project/pull/151750