Bug in AArch64 optimizer when compiling BGRABitmap with trunk compiler

Summary

I have discovered that compiling a simple program that uses BGRA bitmap will crash with the trunk AArch64 compiler and /O2 optimization on Darwin. This issue was introduced to trunk in commit c1d8e32e.

System Information

• Operating system: macOS / Darwin
• Processor architecture: AARCH64
• Compiler version: trunk

Steps to reproduce

1. Download the attached project and build on macOS AArch64 with trunk compiler
2. Note that the program will crash upon execution when compiled with /O2

Example Project

test.zip

Here is the sample code (the attached file above includes all dependencies):

program project1;

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  Classes, SysUtils, bgrabitmap, bgrasvg;

var
  LBgraSvg: TBGRASVG;
  LBgraBitmap: TBGRABitmap;
begin
  Writeln('I was compiled with ', {$I %FPCVERSION%});
  WriteLn('Program started');
  LBgraSvg := TBGRASVG.Create;
  try
    WriteLn('Loading bitmap');
    LBgraSvg.LoadFromFile('bgrabitmap.svg');
    LBgraBitmap := TBGRABitmap.Create(64, 64);
    try
      Writeln('Stretch draw');
      LBgraSvg.StretchDraw(LBgraBitmap.Canvas2D, 0, 0, 64, 64);
      LBgraBitmap.SaveToFile('output.bmp');
      Writeln('Saved output');
    finally
      LBgraBitmap.Free;
    end;
  finally
    LBgraSvg.Free;
  end;
  WriteLn('Program ended');
end.

What is the current bug behavior?

When using the 3.2.3 compiler with either /O1 or /O2, the program works correctly.

When using the 3.3.1 compiler with /O1, the program works correctly, but with /O2 the program crashes.

What is the expected (correct) behavior?

The program must not crash due to a bug in the optimizer.

Relevant logs and/or screenshots

Here is a screen shot of the attached program compiled with 3.2.3 and 3.3.1. As you can see in 3.3.1 when /O2 incorrect code is generated and causes the program to crash.