Am 20.04.20 um 16:44 schrieb Martin:
FPC sometimes generates jump instructions as follows. (Not always bound
to "IF" but that is the example I found
IF something then begin {long code} end;
The conditional asm jump does not jump all the way to the code after the
"end".
Instead it points to an unconditional jump, that (according to line
info) is at the end of some other line.
This might be some artifact introduced by the optimizer. Problem is, the
jumps are generated at a certain point and then the optimizer starts to
"mess" with them. During this, it might be that line info is mixed up.
Such "jump pads" (?) seem common (gdb seems to know about them).
I try to detect them in fpDebug.
Which assumptions are reasonable?
- How long can a series of such "jump forwarders" be.
Can the unconditional jump, go to another unconditional jump, before
eventually hitting the line that the pascal code would go to?
How many to expect max, before getting suspicious?
Unlimited in theory.
- If such jumps are within line info, they should not be at the start of
a line?
Do you have some example code which shows this (together with the needed
optimizer switches)?
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