[sdcc-devel] [ sdcc-Bugs-3536902 ] SEGV with --reserve-regs-iy

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Bugs item #3536902, was opened at 2012-06-21 06:53
Message generated for change (Comment added) made by spth
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Category: z80 port
Group: None
>Status: Closed
Resolution: None
Priority: 5
Private: No
Submitted By: Christophe Staïesse (chastai)
>Assigned to: Philipp Klaus Krause (spth)
Summary: SEGV  with --reserve-regs-iy

Initial Comment:
Hello,

The compiler crash with a SEGV when I try to compile some C files with a z80 target and the --reserve-regs-iy option.
 I've attached an example of source which make the compiler crash. 


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>Comment By: Philipp Klaus Krause (spth)
Date: 2012-06-22 04:18

Message:
Fixed in revision #7953.

Philipp


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Comment By: Philipp Klaus Krause (spth)
Date: 2012-06-22 02:04

Message:
Thanks, knowing the revision # that introduced the bug helped.

It seems the special handling ot --reserve-regs-iy was lost when factoring
out some port-specific stuff from the generic register allocator code.

I've got two ideas for a fix, one a quick hack, which might make it into
the 3.2.0 release, and a cleaner, but bigger solution that seems to be a
good long-term solution.

Philipp

P.S.: With the quick hack, regression tests pass when using
--reserve-regs-iy, except for one failing test, and do not crash the
compiler any more; I'll implement the cleaner solution in a branch later
today.

P.P.S.: --reserve-regs-iy isn't perfect yet: For functions that use more
than 128 bytes of stack space for local variables or that have more than
128 bytes of parameters, iy is still used.


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Comment By: Christophe Staïesse (chastai)
Date: 2012-06-22 01:17

Message:
Unfortunately, the problem persists even if you remove printf. In fact many
source files makes the compiler crashes with this option.

Try to compile the Z80 RTL with --reserve-regs-iy:

cd device/lib/z80
rm *.rel
make -k  SCC='$(top_builddir)/bin/sdcc -mz80 --reserve-regs-iy'

On 105 C files, 86 caused a SEGV, 3 an ABRT and only 16 compiled with
success.
And from the 16 .asm generated, 10 contain references to IY.

if you add --oldralloc, it works fine but some .asm still contains
references to IY.

The problem appears on revision 7537. On 7536, the RTL compile fines with
--reserve-regs-iy but there are still references to IY.

Christophe.

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Comment By: Philipp Klaus Krause (spth)
Date: 2012-06-21 08:37

Message:
Hmm, for some reason emitCall thinks that the return value of printf() is
used when using --reserve-regs-iy, and tries to assign it to a non-exisitng
variable.

Philipp


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Comment By: Christophe Staïesse (chastai)
Date: 2012-06-21 07:02

Message:
sorry I pushed on the wrong button :-)

I've made a regression test and this bug occurs from revision 7537. 

How to reproduce this bug (I've used revision 7950):

 sdcc -mz80 --reserve-regs-iy reserve-regs-iy-bug.c

Program received signal SIGSEGV, Segmentation fault.
cheapMove (to=0x1, to_offset=0, from=0x81b5eec, from_offset=0) at
gen.c:2800
2800	  if (to->type == AOP_ACC && from->type == AOP_ACC && to_offset ==
from_offset)

But when I compile it with --oldralloc, it works fine.

Christophe.

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