[Flang] [AIX] Incorrect `sqrt` folding on AIX.

[DanielCChen]

Consider the following code:

complex :: cv = sqrt((-2.0,0.0))
END

On AIX, it generates

    %cst = arith.constant -6.18172393E-8 : f32
    %cst_0 = arith.constant 1.41421354 : f32

On LoP, it generates

    %cst = arith.constant 0.000000e+00 : f32
    %cst_0 = arith.constant 1.41421354 : f32

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: Daniel Chen (DanielCChen)

Consider the following code: ``` complex :: cv = sqrt((-2.0,0.0)) END ```

On AIX, it generates

    %cst = arith.constant -6.18172393E-8 : f32
    %cst_0 = arith.constant 1.41421354 : f32

On LoP, it generates

    %cst = arith.constant 0.000000e+00 : f32
    %cst_0 = arith.constant 1.41421354 : f32

[klausler]

That's a complex square root, and those are folded using the local math library to which the compiler has been linked.

[DanielCChen]

That's a complex square root, and those are folded using the local math library to which the compiler has been linked.

I see. Thanks for the pointer.

[kkwli]

It is desirable to make the folding result and the runtime result the same. On AIX, the cacos and csqrt give different output.

  complex :: c1, r1, r2
  complex, parameter :: c2 = (-2.0, 0.0)
  r1 = csqrt((-2.0, 0.0))
  c1 = (-2.0, 0.0)
  r2 = csqrt(c1)
  print *, r1
  print *, r2
end

Output:

 (-6.181724E-08,1.4142135)
 (0.,1.4142135)

[kkwli]

Fixed in #114106