Am Sat, 22 Jul 2017 08:11:28 +0000
schrieb Mike <n...@none.com>:
> On Friday, 21 July 2017 at 23:44:53 UTC, Mike wrote:
>
> > However, I'm getting broken binaries with -O2 and -O3. I've
> > nailed the culprit down to -fschedule-insns (i.e. if I add
> > -fno-schedule-insns to -O2 or -O3, the binary works fine).
>
> I've confirmed that -fschedule-insns is reordering register
> access even though they are being accessed with
> volatileLoad/Store. Read the comments in the following code for
> understanding. FYI A bit-banded address is a 32-bit address to a
> single bit.
>
> Here's the D code
> -----------------
> // This is a single atomic store to bit-banded address 0x42470048
> RCC.CR.HSEBYP.value = false;
>
> // This is a single read-modify-write to non-bit-banded 32-bit
> address 0x40023808
> with(RCC.CFGR)
> {
> setValue
> !(
> MCO2, 0
> , MCO2PRE, 0
> , MCO1PRE, 0
> , I2SSRC, 0
> , MCO1, 0
> , RTCPRE, 0
> , HPRE, 0b000
> , PPRE2, 0b100
> , PPRE1, 0b101
> , SW, 0
> )();
> }
>
I guess this doesn't happen for a reduced example directly using
volatileLoad/volatileStore? If you could provide such a reduced example
that'd be very useful.
-- Johannes
