This is a v2 of: https://gcc.gnu.org/pipermail/gcc-patches/2024-August/659969.html this version just streams the flag as requested.
Bootstrapped/tested as a series on aarch64-linux-gnu (both with and without LTO), OK for trunk? Thanks, Alex -- >8 -- When #pragma GCC unroll is processed in tree-cfg.cc:replace_loop_annotate_in_block, we set both the loop->unroll field (which is currently streamed during LTO) but also the cfun->has_unroll flag. cfun->has_unroll, however, is not currently streamed during LTO. This patch fixes that. Prior to this patch, loops marked with #pragma GCC unroll that would be unrolled by RTL loop2_unroll in a non-LTO compilation didn't get unrolled under LTO. gcc/ChangeLog: PR libstdc++/116140 * lto-streamer-in.cc (input_struct_function_base): Stream in fn->has_unroll. * lto-streamer-out.cc (output_struct_function_base): Stream out fn->has_unroll. gcc/testsuite/ChangeLog: PR libstdc++/116140 * g++.dg/ext/pragma-unroll-lambda-lto.C: New test. --- gcc/lto-streamer-in.cc | 1 + gcc/lto-streamer-out.cc | 1 + .../g++.dg/ext/pragma-unroll-lambda-lto.C | 32 +++++++++++++++++++ 3 files changed, 34 insertions(+) create mode 100644 gcc/testsuite/g++.dg/ext/pragma-unroll-lambda-lto.C
diff --git a/gcc/lto-streamer-in.cc b/gcc/lto-streamer-in.cc index 64f75807328..9d0ec5d589c 100644 --- a/gcc/lto-streamer-in.cc +++ b/gcc/lto-streamer-in.cc @@ -1326,6 +1326,7 @@ input_struct_function_base (struct function *fn, class data_in *data_in, fn->has_force_vectorize_loops = bp_unpack_value (&bp, 1); fn->has_simduid_loops = bp_unpack_value (&bp, 1); fn->has_musttail = bp_unpack_value (&bp, 1); + fn->has_unroll = bp_unpack_value (&bp, 1); fn->assume_function = bp_unpack_value (&bp, 1); fn->va_list_fpr_size = bp_unpack_value (&bp, 8); fn->va_list_gpr_size = bp_unpack_value (&bp, 8); diff --git a/gcc/lto-streamer-out.cc b/gcc/lto-streamer-out.cc index 523d6dad221..52d0d737330 100644 --- a/gcc/lto-streamer-out.cc +++ b/gcc/lto-streamer-out.cc @@ -2283,6 +2283,7 @@ output_struct_function_base (struct output_block *ob, struct function *fn) bp_pack_value (&bp, fn->has_force_vectorize_loops, 1); bp_pack_value (&bp, fn->has_simduid_loops, 1); bp_pack_value (&bp, fn->has_musttail, 1); + bp_pack_value (&bp, fn->has_unroll, 1); bp_pack_value (&bp, fn->assume_function, 1); bp_pack_value (&bp, fn->va_list_fpr_size, 8); bp_pack_value (&bp, fn->va_list_gpr_size, 8); diff --git a/gcc/testsuite/g++.dg/ext/pragma-unroll-lambda-lto.C b/gcc/testsuite/g++.dg/ext/pragma-unroll-lambda-lto.C new file mode 100644 index 00000000000..144c4c32692 --- /dev/null +++ b/gcc/testsuite/g++.dg/ext/pragma-unroll-lambda-lto.C @@ -0,0 +1,32 @@ +// { dg-do link { target c++11 } } +// { dg-options "-O2 -flto -fdump-rtl-loop2_unroll" } + +#include <cstdlib> + +template<typename Iter, typename Pred> +inline Iter +my_find(Iter first, Iter last, Pred pred) +{ +#pragma GCC unroll 4 + while (first != last && !pred(*first)) + ++first; + return first; +} + +__attribute__((noipa)) +short *use_find(short *p) +{ + auto pred = [](short x) { return x == 42; }; + return my_find(p, p + 1024, pred); +} + +int main(void) +{ + short a[1024]; + for (int i = 0; i < 1024; i++) + a[i] = rand (); + + return use_find (a) - a; +} + +// { dg-final { scan-ltrans-rtl-dump-times "Unrolled loop 3 times" 1 "loop2_unroll" } }