> On Oct 4, 2021, at 12:19 PM, Richard Biener <rguent...@suse.de> wrote: > > On October 4, 2021 7:00:10 PM GMT+02:00, Qing Zhao <qing.z...@oracle.com> > wrote: >> I have several questions on this fix: >> >> 1. This fix avoided expanding “.DEFERRED_INIT” when !tree_fits_uhwi_p >> (TYPE_SIZE_UNIT (var_type)). >> As a result, this call to .DEFERRED_INIT will NOT be expanded at all. > > Yes.
Then, should we exclude such auto init during gimplification phase? > >> Then not expanding .DEFERRED_INIT in RTL expanding phase will trigger more >> issues in later RTL phases, this looks not correct to me. (Actually, with is >> the patch, this testing case still failed in a later RTL stage). >> >> So, If we really want to avoid auto-init for VLA vectors, we should not >> add call to .DEFERRED_INIT in gimplification phase at all. >> >> >> 2. For the added .DEFERRED_INIT: >> >> __SVFloat64_t f64; >> >> f64 = .DEFERRED_INIT (POLY_INT_CST [16, 16], 2, 0); >> >> What does “POLY_INT_CST[16,16]” mean? Is this a constant size? If YES, >> what’s the value of it? If Not, can we use “memset” to expand it? > > When the target is a register memset doesn't work. I'm not sure the memset > expansion path will work as-is either for aggregates with vla parts - Stupid question here: what does POLY_INT_CST[16,16] mean? It’s not a constant? Qing > but I'll leave that to Richard S. to sort out. > > Richard. > >> Thanks. >> >> Qing >> >> >> >>> On Oct 4, 2021, at 3:57 AM, Richard Biener via Gcc-patches >>> <gcc-patches@gcc.gnu.org> wrote: >>> >>> This avoids ICEing for VLA vector auto-init by not initializing. >>> >>> Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed. >>> >>> 2021-10-04 Richard Biener <rguent...@suse.de> >>> >>> PR middle-end/102587 >>> * internal-fn.c (expand_DEFERRED_INIT): Guard register >>> initialization path an avoid initializing VLA registers >>> with it. >>> >>> * gcc.target/aarch64/sve/pr102587-1.c: New testcase. >>> * gcc.target/aarch64/sve/pr102587-2.c: Likewise. >>> --- >>> gcc/internal-fn.c | 3 ++- >>> gcc/testsuite/gcc.target/aarch64/sve/pr102587-1.c | 4 ++++ >>> gcc/testsuite/gcc.target/aarch64/sve/pr102587-2.c | 4 ++++ >>> 3 files changed, 10 insertions(+), 1 deletion(-) >>> create mode 100644 gcc/testsuite/gcc.target/aarch64/sve/pr102587-1.c >>> create mode 100644 gcc/testsuite/gcc.target/aarch64/sve/pr102587-2.c >>> >>> diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c >>> index 8312d08aab2..ef5dc90db56 100644 >>> --- a/gcc/internal-fn.c >>> +++ b/gcc/internal-fn.c >>> @@ -3035,7 +3035,8 @@ expand_DEFERRED_INIT (internal_fn, gcall *stmt) >>> /* Expand this memset call. */ >>> expand_builtin_memset (m_call, NULL_RTX, TYPE_MODE (var_type)); >>> } >>> - else >>> + /* ??? Deal with poly-int sized registers. */ >>> + else if (tree_fits_uhwi_p (TYPE_SIZE_UNIT (var_type))) >>> { >>> /* If this variable is in a register, use expand_assignment might >>> generate better code. */ >>> diff --git a/gcc/testsuite/gcc.target/aarch64/sve/pr102587-1.c >>> b/gcc/testsuite/gcc.target/aarch64/sve/pr102587-1.c >>> new file mode 100644 >>> index 00000000000..2b9a68b0b59 >>> --- /dev/null >>> +++ b/gcc/testsuite/gcc.target/aarch64/sve/pr102587-1.c >>> @@ -0,0 +1,4 @@ >>> +/* { dg-do compile } */ >>> +/* { dg-options "-ftrivial-auto-var-init=zero" } */ >>> + >>> +void foo() { __SVFloat64_t f64; } >>> diff --git a/gcc/testsuite/gcc.target/aarch64/sve/pr102587-2.c >>> b/gcc/testsuite/gcc.target/aarch64/sve/pr102587-2.c >>> new file mode 100644 >>> index 00000000000..4cdb9056002 >>> --- /dev/null >>> +++ b/gcc/testsuite/gcc.target/aarch64/sve/pr102587-2.c >>> @@ -0,0 +1,4 @@ >>> +/* { dg-do compile } */ >>> +/* { dg-options "-ftrivial-auto-var-init=pattern" } */ >>> + >>> +void foo() { __SVFloat64_t f64; } >>> -- >>> 2.31.1 >> >