Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}. Ok for trunk. gcc/ChangeLog:
PR rtl/103750 * cfgloop.h (loop_contains_p): New function. * fwprop.c (forward_propagate_into): Allow propagations from inner loop to outer loop. gcc/testsuite/ChangeLog: * g++.target/i386/pr103750-fwprop-1.C: New test. --- gcc/cfgloop.h | 12 +++++++++ gcc/fwprop.c | 7 +++-- .../g++.target/i386/pr103750-fwprop-1.C | 26 +++++++++++++++++++ 3 files changed, 43 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/g++.target/i386/pr103750-fwprop-1.C diff --git a/gcc/cfgloop.h b/gcc/cfgloop.h index d2714e20cb0..e8fe0cedd5f 100644 --- a/gcc/cfgloop.h +++ b/gcc/cfgloop.h @@ -908,6 +908,18 @@ loop_outermost (class loop *loop) return (*loop->superloops)[1]; } +/* Returns true if loop OUTER contains loop INNER. */ +static inline bool +loop_contains_p (class loop* outer, class loop* inner) +{ + unsigned n = vec_safe_length (inner->superloops); + + for (unsigned i = 0; i != n; i++) + if ((*inner->superloops)[i] == outer) + return true; + return false; +} + extern void record_niter_bound (class loop *, const widest_int &, bool, bool); extern HOST_WIDE_INT get_estimated_loop_iterations_int (class loop *); extern HOST_WIDE_INT get_max_loop_iterations_int (const class loop *); diff --git a/gcc/fwprop.c b/gcc/fwprop.c index 2eab4fd4614..aed48e7273f 100644 --- a/gcc/fwprop.c +++ b/gcc/fwprop.c @@ -866,10 +866,13 @@ forward_propagate_into (use_info *use, bool reg_prop_only = false) rtx src = SET_SRC (def_set); /* Allow propagations into a loop only for reg-to-reg copies, since - replacing one register by another shouldn't increase the cost. */ + replacing one register by another shouldn't increase the cost. + Propagations from inner loop to outer loop should be also ok. */ struct loop *def_loop = def_insn->bb ()->cfg_bb ()->loop_father; struct loop *use_loop = use->bb ()->cfg_bb ()->loop_father; - if ((reg_prop_only || def_loop != use_loop) + if ((reg_prop_only + || (use_loop && def_loop != use_loop + && !loop_contains_p (use_loop, def_loop))) && (!reg_single_def_p (dest) || !reg_single_def_p (src))) return false; diff --git a/gcc/testsuite/g++.target/i386/pr103750-fwprop-1.C b/gcc/testsuite/g++.target/i386/pr103750-fwprop-1.C new file mode 100644 index 00000000000..26987d307aa --- /dev/null +++ b/gcc/testsuite/g++.target/i386/pr103750-fwprop-1.C @@ -0,0 +1,26 @@ +/* PR target/103750. */ +/* { dg-do compile } */ +/* { dg-options "-O2 -std=c++1y -march=cannonlake -fdump-rtl-fwprop1" } */ +/* { dg-final { scan-rtl-dump-not "subreg:HI\[ \\\(\]*reg:SI\[^\n]*\n\[^\n]*UNSPEC_TZCNT" "fwprop1" } } */ + +#include<immintrin.h> +const char16_t *qustrchr(char16_t *n, char16_t *e, char16_t c) noexcept +{ + __m256i mch256 = _mm256_set1_epi16(c); + for ( ; n < e; n += 32) { + __m256i data1 = _mm256_loadu_si256(reinterpret_cast<const __m256i *>(n)); + __m256i data2 = _mm256_loadu_si256(reinterpret_cast<const __m256i *>(n) + 1); + __mmask16 mask1 = _mm256_cmpeq_epu16_mask(data1, mch256); + __mmask16 mask2 = _mm256_cmpeq_epu16_mask(data2, mch256); + if (_kortestz_mask16_u8(mask1, mask2)) + continue; + + unsigned idx = _tzcnt_u32(mask1); + if (mask1 == 0) { + idx = __tzcnt_u16(mask2); + n += 16; + } + return n + idx; + } + return e; +} -- 2.18.1