Found the reason for it, or at least what looks like the reason... the
RemoveDeadCodeAfterJump routine, which removes all instructions between
a "jmp" instruction and the next live label (since those instructions
will never get executed), doesn't stop if it hits the SEH section and
strips all that too. Because of the "while True do" block covering the
entire procedure, the function epilogue is suppressed by an
unconditional jump and so gets stripped out (arguably fine in this
case), but the optimizer doesn't think to stop if it goes past the final
instruction. I'll start doing a bisect to see if I can locate where
this is corrected... or just write it myself if that fails.
Gareth aka. Kit
On 15/01/2022 15:25, Florian Klämpfl via fpc-devel wrote:
Am 13.01.2022 um 16:49 schrieb Martin Frb via fpc-devel:
In the below code compiled with 3.2.3 (today and early Dec)
when the exception is reached the app exits.
There is no code from finally, nor from except block executed.
The "randomize" is just to put some code into each block. No special
meaning otherwise.
This issue is on Win64. (works for 32 bit Win)
And appears to be ok in 3.3.1.
It happens only with -O1 or higher, the compiler optimizes away all
the exception data (diff between -O- and -O1):
176,180d170
< # [37] end;
< nop
< leaq (%rbp),%rsp
< popq %rbp
< ret
183,195d172
< .long 3
< .long 0
< .rva .Lj27
< .rva .Lj28
< .rva P$PROJECT1$_$FOO_$$_fin$00000002
< .long 0
< .rva .Lj22
< .rva .Lj23
< .rva P$PROJECT1$_$FOO_$$_fin$00000003
< .long 1
< .rva .Lj20
< .rva .Lj17
< .rva .Lj18
199a177
> # [37] end;
Maybe Gareth can have a look?
program Project1;
{$mode objfpc}{$H+}
uses SysUtils;
var
bar: boolean;
procedure Foo;
begin
while true do begin
try
try
try
if bar then
raise Exception.Create('');
Randomize;
finally
Randomize;
try
Randomize;
finally
Randomize;
end;
end;
Randomize;
finally
Randomize;
end;
Randomize;
except
bar := false;
Randomize;
end;
end;
end;
begin
bar := true;
Foo;
end.
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