Re: PR 33089: Canonicalizing a + b != 0 as a != -b causes missed optimization

2007-08-20 Thread Hans-Peter Nilsson
On Fri, 17 Aug 2007, Rask Ingemann Lambertsen wrote: >We start out with (eq (plus X A) 0): >I want to hear some opinions on which form we should choose as the > canonical one. I'm proposing two forms: > > 1) (eq (neg X) Y) because the change to simplify_comparison will be simpler. > 2) (e

PR 33089: Canonicalizing a + b != 0 as a != -b causes missed optimization

2007-08-17 Thread Rask Ingemann Lambertsen
We start out with (eq (plus X A) 0): simplify_comparison (code=EQ, pop0=0xbfd722b4, pop1=0xbfd722b0) at /home/rask/cvssrc/ia16-gcc/gcc/combine.c:9915 (gdb) call debug_rtx (*pop0) (plus:SI (reg/v:SI 59 [ b ]) (mem/c/i:SI (reg/f:SI 16 argp) [2 a+0 S4 A32])) (gdb) call debug_rtx (*pop1) (co