AIX FPU exception handling broken

Summary

Startup code sets XE bit in $fpscr register, leading to exception generation as soon as a FPU operation sets "inexact result". See: https://www.classe.cornell.edu/~cesrulib/documentation/totalview/html/Reference_Guides/wwhelp/wwhimpl/common/html/wwhelp.htm#href=UsingthePowerFPSCRRegister.html&single=true

System Information

• **Operating system:**AIX
• Processor architecture: powerpc and powerpc64
• **Compiler version:**3.3.1
• Device:

Steps to reproduce

Compile and run source below.

Example Project

var
  d1,d2 : double;
{$if defined(VER3_3) and not defined(AIX) }
  fpscr: TNativeFPUControlWord;
{$else}
  fpscr : DWord;


function getFPSCR : DWord; assembler; nostackframe;
asm
  mffs f0
  stfd f0, -12(r1)
  lwz r3, -8(r1)
end;

{$endif}
begin
{$if defined(VER3_3) and not defined(AIX)}
  fpscr:=GetNativeFPUControlWord;
{$else}
  fpscr:=getFPSCR;
{$endif}
  writeln('fpscr=$',hexstr(qword(fpscr),2*sizeof(qword)));
  d1:=1.0;
  d2:=155;
  d2:=d1/d2;
  writeln('d2=',d2);
end.

What is the current bug behavior?

The test generates this output:

fpscr=$00000000000000F8
Runtime error 207 at $000000010000059C

What is the expected (correct) behavior?

On powerpc-linux or powerpc64-linux fpscr is set to 090, and in RTE 207 is generated. AIX code should generate the same behavior.

Relevant logs and/or screenshots

Possible fixes

code in rtl/ppcgen//ppcfpuex.inc needs fixing.