On Thu, Apr 28, 2022 at 10:31 AM Jakub Jelinek <ja...@redhat.com> wrote: > > Hi! > > I'd like to ping this patch. I know it isn't a full week yet, but we are > almost out of P1s and GCC 12 branching is any time now. > > Thanks: > On Fri, Apr 22, 2022 at 09:25:04AM +0200, Jakub Jelinek via Gcc-patches wrote: > > On the following testcase we emit a bogus > > 'va_arg_tmp.5' may be used uninitialized > > warning. The reason is that when gimplifying the addr = &temp; > > statement, the va_arg_tmp temporary var for which we emit ADDR_EXPR > > is not TREE_ADDRESSABLE, prepare_gimple_addressable emits some extra > > code to initialize the newly addressable var from its previous value, > > but it is a new variable which hasn't been initialized yet and will > > be later, so we end up initializing it with uninitialized SSA_NAME: > > va_arg_tmp.6 = va_arg_tmp.5_14(D); > > addr.2_16 = &va_arg_tmp.6; > > _17 = MEM[(double *)sse_addr.4_13]; > > MEM[(double * {ref-all})addr.2_16] = _17; > > and with -O1 we actually don't DSE it before the warning is emitted. > > If we make the temp TREE_ADDRESSABLE before the gimplification, then > > this prepare_gimple_addressable path isn't taken and we effectively > > omit the first statement above and so the bogus warning is gone. > > > > I went through other backends and didn't find another instance of this > > problem. > > > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? > > > > 2022-04-22 Jakub Jelinek <ja...@redhat.com> > > > > PR target/105331 > > * config/i386/i386.cc (ix86_gimplify_va_arg): Mark va_arg_tmp > > temporary TREE_ADDRESSABLE before trying to gimplify ADDR_EXPR > > of it. > > > > * gcc.dg/pr105331.c: New test.
Sorry, I have no idea if this patch is correct or not. Uros.