On Tue, Jul 7, 2026 at 4:36 PM Roger Sayle <[email protected]> wrote:
>
>
> Hi Richard,
> Thanks for the review. Here's a revised patch incorporating your feedback.
> I'd considered arguing that none of the other callers of vec_init_optab in
> the middle-end currently allow it to FAIL, but with the factorization into
> a helper function (so that icode doesn’t have to be looked up twice), it's
> trivially easy to handle it here (and perhaps update the other callers in
> future).
Yeah, it might be a documentation omission but I didn't check whether
any targets vec_init can actually fail.
> This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
> and make -k check, both with and without --target_board=unix{-m32}
> with no new failures. Ok for mainline?
LGTM, I'm always a bit nervous with endianess issues, but I _think_
you got that correct. Please wait a day or two so anybody else can
double-check that.
Thanks,
Richard.
> 2026-07-07 Roger Sayle <[email protected]>
> Richard Biener <[email protected]>
>
> gcc/ChangeLog
> PR target/99668
> * expr.cc (try_expand_complex_as_vector): Try to use vec_init_optab
> to convert a complex number to a two-component vector with the same
> inner type.
> (expand_expr_real_1) <case VIEW_CONVERT_EXPR>: Check whether the
> above function can be used to implement this VIEW_CONVERT_EXPR.
>
> gcc/testsuite/ChangeLog
> PR target/99668
> * gcc.target/i386/pr99668.c: New test case.
>
>
> Thanks again,
> Roger
> --
> > -----Original Message-----
> > From: Richard Biener <[email protected]>
> > Sent: 01 July 2026 08:25
> > To: Roger Sayle <[email protected]>
> > Cc: GCC Patches <[email protected]>
> > Subject: Re: [PATCH] PR target/99668: Improved complex to vector RTL
> > expansion.
> >
> > On Tue, Jun 30, 2026 at 11:42 PM Roger Sayle <[email protected]>
> > wrote:
> > >
> > >
> > > This patch improves the RTL expansion of casts (VIEW_CONVERT_EXPR)
> > > from complex numbers to two-component vectors with the same inner
> > > type. Currently, expand spills the complex number to memory to
> > > perform this conversion. With the patch below we now convert the
> > > V_C_E into the equivalent of (v2x){__real__ z,__imag__ z}, using the
> > > backend's vec_init_optab.
> > >
> > > The motivating example from the Bugzilla PR is:
> > >
> > > typedef double v2df __attribute__((vector_size(16))); v2df foo
> > > (_Complex double x) {
> > > return *(v2df *)&x;
> > > }
> > >
> > > Currently, with -O2 GCC implements this by spilling to memory:
> > >
> > > foo: movsd %xmm0, -24(%rsp)
> > > movsd %xmm1, -16(%rsp)
> > > movupd -24(%rsp), %xmm0
> > > ret
> > >
> > > with this enhancement to RTL expansion, we now generate:
> > >
> > > foo: unpcklpd %xmm1, %xmm0
> > > ret
> > >
> > > The improvement with -m32 -msse2 -O2 is even more pronounced.
> > >
> > > From: subl $28, %esp
> > > movsd 32(%esp), %xmm1
> > > movsd 40(%esp), %xmm2
> > > movsd %xmm1, (%esp)
> > > movsd %xmm2, 8(%esp)
> > > movupd (%esp), %xmm0
> > > addl $28, %esp
> > > ret
> > >
> > > To: movq 4(%esp), %xmm0
> > > movhpd 12(%esp), %xmm0
> > > ret
> > >
> > >
> > > This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
> > > and make -k check, both with and without --target_board=unix{-m32}
> > > with no new failures. Ok for mainline?
> >
> > I'll note the documentation of vec_init doesn't state the pattern is not
> > allowed to
> > FAIL, so I think you need to handle the expander failing.
> >
> > Also
> >
> > + if (!REG_P (rpart) && !CONSTANT_P (rpart))
> > + rpart = force_reg (GET_MODE_INNER (mode), rpart);
> > + if (!REG_P (ipart) && !CONSTANT_P (ipart))
> >
> > I think there's one extra space after part) and it would be nice to do the
> > icode =
> > convert_optab_handler assignment as part of the if () to not repeat it.
> >
> > Otherwise a good idea.
> >
> > Thanks,
> > Richard.
> >
> > >
> > >
> > > 2026-06-30 Roger Sayle <[email protected]>
> > >
> > > gcc/ChangeLog
> > > PR target/99668
> > > * expr.cc (expand_expr_real_1) <case VIEW_CONVERT_EXPR>: Use
> > > vec_init_optab to convert a complex number into two-component
> > > vector with the same inner type.
> > >
> > > gcc/testsuite/ChangeLog
> > > PR target/99668
> > > * gcc.target/pr99668.c: New test case.
> > >
> > >
> > > Thanks in advance,
> > > Roger
> > > --
> > >
