[Bug middle-end/82051] [mips]mips emit different results when compiling union var using -O0/-O2
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82051 YunQiang Su changed: What|Removed |Added Resolution|--- |INVALID CC||syq at gcc dot gnu.org Status|UNCONFIRMED |RESOLVED --- Comment #4 from YunQiang Su --- So, we believes that it is invalid.
[Bug middle-end/82051] [mips]mips emit different results when compiling union var using -O0/-O2
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82051
--- Comment #3 from joseph at codesourcery dot com ---
On Thu, 31 Aug 2017, zwzhangwen.zhang at huawei dot com wrote:
>volatile long long f1;
> printf ("g_121.f1=%x\n",g_121.f1);
In addition to the other points people have made about active union
members, %x is not the correct format for long long; use %llx.
[Bug middle-end/82051] [mips]mips emit different results when compiling union var using -O0/-O2
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82051
Richard Biener changed:
What|Removed |Added
CC||rguenth at gcc dot gnu.org
--- Comment #2 from Richard Biener ---
(In reply to Andrew Pinski from comment #1)
> I don't know if this is defined or not. Basically 0x549E5CE9L is really
> 0xCE9 which is stored in the bit-field. The rest of the bits might be still
> undefined or zero. I don't remember what the C standard says here.
They are undefined. The question is what the standard says about the
initializer, what union member gets initialized / activated. One may read
6.7.9/20 as to
always the first member being initialized / activated.
In this case this PR is INVALID.
I suppose you want = { .f1 = 0x549E5CE9L };
[Bug middle-end/82051] [mips]mips emit different results when compiling union var using -O0/-O2
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82051 Andrew Pinski changed: What|Removed |Added Component|c |middle-end --- Comment #1 from Andrew Pinski --- I don't know if this is defined or not. Basically 0x549E5CE9L is really 0xCE9 which is stored in the bit-field. The rest of the bits might be still undefined or zero. I don't remember what the C standard says here.
