Re: GCC 4.1.2 for ARM (in NetBSD 4) produces buggy code with-fno-strict-aliasing?

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

gavare%gmail.com@localhost wrote:

> By manually compiling wi.o and removing optimization options from the
> command line, I noticed that removing -fno-strict-aliasing causes the
> buggy code to be replaced with more reasonable code:

I think the real problem is -fregmove, which is enabled by -O2.
With -fno-regmove, it generates:
---
    3b7c:       e51b40d0        ldr     r4, [fp, #-208]
    3b80:       e51b50d0        ldr     r5, [fp, #-208]
    3b84:       e5943eb4        ldr     r3, [r4, #3764]
    3b88:       e5944eb8        ldr     r4, [r4, #3768]
---

Enabling -fstrict-aliasing (also enabled by -O2 but disabled by default
on NetBSD kernel) could make some difference as a side effect
because "ptr = (u_int32_t *)&sc->sc_stats;" statement may break
strict aliasing rule.
---
Izumi Tsutsui