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Re: abort in eliminate_regs compiling glob.c from glibc
- To: dave at hiauly1 dot hia dot nrc dot ca (John David Anglin)
- Subject: Re: abort in eliminate_regs compiling glob.c from glibc
- From: "John David Anglin" <dave at hiauly1 dot hia dot nrc dot ca>
- Date: Tue, 14 Nov 2000 16:40:52 -0500 (EST)
- Cc: parisc-linux at thepuffingroup dot com, gcc-bugs at gcc dot gnu dot org, gcc-patches at gcc dot gnu dot org
> > Breakpoint 2, eliminate_regs_in_insn (insn=0x406a0ba0, replace=0)
> > at ../../gcc/reload1.c:2826
> > 2826 if (! insn_is_asm && icode < 0)
> > (gdb) p debug_rtx (insn)
> > (insn/s 2711 2709 2719 (set (reg:SI 6 %r6)
> > (reg:SI 28 %r28)) 69 {pre_ldw-4} (insn_list 2708 (insn_list:REG_DEP_ANTI 2696 (insn_list:REG_DEP_ANTI 2702 (insn_list:REG_DEP_ANTI 2697 (nil)))))
> > (expr_list:REG_DEAD (reg:SI 28 %r28)
> > (insn_list:REG_RETVAL 2708 (expr_list:REG_EQUAL (expr_list (use (mem:BLK (scratch) 0))
> > (expr_list (symbol_ref/v:SI ("@strlen"))
> > (expr_list (reg/v:SI 4 %r4)
> > (nil))))
> > (nil)))))
>
> The `use' arises from the `__pure__' attribute in the prototype for strlen:
>
> extern size_t strlen (__const char *__s) __attribute__ ((__pure__));
Here is a patch to fix the abort in eliminate_regs when it encounters a USE.
As I understand the situation, there are three conditions needed to trigger
it:
1) A function that contains insns with an eliminable register.
2) The function must call __builtin_alloca to change the frame size
from its initial size.
3) After the call to __builtin_alloca, there must be a call to a
pure function.
With the enclosed patch, I can now build glibc for hppa-linux with -O3
optimisation.
Please review carefully because I will be the first to admit that I don't
understand why the use is there in the first place and all the details of
what eliminate_reg does.
Dave
--
J. David Anglin dave.anglin@nrc.ca
National Research Council of Canada (613) 990-0752 (FAX: 952-6605)
2000-11-14 John David Anglin <dave@hiauly1.hia.nrc.ca>
* reload1.c (eliminate_regs): Don't abort on MEM USEs.
--- reload1.c.orig Wed Sep 27 14:27:23 2000
+++ reload1.c Tue Nov 14 16:01:56 2000
@@ -2499,6 +2499,10 @@
return x;
case USE:
+ /* Handle insn_list USE that a call to a pure functions may generate. */
+ new = eliminate_regs (XEXP (x, 0), 0, insn);
+ if (GET_CODE (new) == MEM)
+ return XEXP (new, 0);
case CLOBBER:
case ASM_OPERANDS:
case SET: