On Thu, May 21, 2026 at 8:40 PM Andrew Pinski
<[email protected]> wrote:
>
> On Thu, May 21, 2026 at 8:31 PM Jeffrey Law
> <[email protected]> wrote:
> >
> >
> >
> > On 5/18/2026 9:39 PM, [email protected] wrote:
> > > Dear contributor,
> > >
> > > Our automatic CI has detected problems related to your patch(es). Please
> > > find some details below.
> > >
> > > In aarch64 native, after:
> > > | commit gcc-17-577-gbc19036af435
> > > | Author: Jeff Law <[email protected]>
> > > | Date: Mon May 18 15:17:27 2026 -0600
> > > |
> > > | [RISC-V] Improve ext-dce's live bit tracking for IOR/AND with a
> > > constant argument
> > > |
> > > | Investigation of a regression with some RISC-V target changes
> > > exposed a clear
> > > | missed optimization in ext-dce.c
> > > |
> > > | ... 67 lines of the commit log omitted.
> > >
> > > Produces 2 regressions:
> > > |
> > > | regressions.sum:
> > > | Running gcc:gcc.target/aarch64/aarch64.exp ...
> > > | FAIL: gcc.target/aarch64/tbz_1.c check-function-bodies g1
> > > | FAIL: gcc.target/aarch64/tbz_1.c check-function-bodies g2
> > I've reproduced this locally. I haven't gotten into the debug cycle
> > yet, but wanted folks to know it's mine AFAICT to avoid duplicating
> > debugging efforts.
>
> I think the fix is just a testcase fix.
> Currently the testcase has:
> ** tbnz w[0-9]+, #?0, .L([0-9]+)
>
> But that should just can be:
> ** tbnz [wx][0-9]+, #?0, .L([0-9]+)
>
> to match both x0 and w0 there. But are valid in this case with bit 0.
> For both g1 and g2.
Otherwise this is the fix to the backend:
```
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index f7e2e4be10e..89f0c78e540 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -1091,6 +1091,8 @@ (define_insn "@aarch64_tbz<optab><ALLI:mode><GPI:mode>"
return "tst\t%<ALLI:w>0, %1\;<bcond>\t%l2";
}
}
+ else if (UINTVAL (operands[1]) <= 31)
+ return "<tbz>\t%w0, %1, %l2";
else
return "<tbz>\t%<ALLI:w>0, %1, %l2";
}
```
But that might have more testcase fallout.
I will go and test that one and see what other testcase fallout there
is because I think we want this change anyways; the backend is moving
towards using w form for things if possible anyways.
Thanks
Andrea
>
> Thanks,
> Andrea
>
>
> >
> > jeff
