We'd like to add vec_duplicate_optab to x86 backend. There are 3 ways to broadcast an integer constant:
1. Load the full size from constant pool directly. 2. Use AVX2/AVX512 broadcast instruction. 3. Emulate broadcast with SSE2 unpack and shuffle instructions. A small benchmark: https://gitlab.com/x86-benchmarks/microbenchmark/-/tree/memset/broadcast shows that broadcast is a little bit faster on Intel Core i7-8559U: $ make gcc -g -I. -O2 -c -o test.o test.c gcc -g -c -o memory.o memory.S gcc -g -c -o broadcast.o broadcast.S gcc -g -c -o vec_dup_sse2.o vec_dup_sse2.S gcc -o test test.o memory.o broadcast.o vec_dup_sse2.o ./test memory : 147215 broadcast : 121213 vec_dup_sse2: 171366 $ broadcast is also smaller: $ size memory.o broadcast.o text data bss dec hex filename 132 0 0 132 84 memory.o 122 0 0 122 7a broadcast.o $ The preferred choices are 1. Use AVX2/AVX512 broadcast instruction. 2. Load the full size from constant pool directly. 3. Emulate broadcast with SSE2 unpack and shuffle instructions. The first patch updates vec_duplicate_optab usage to allow it to fail so that x86 backend can opt out SSE2 broadcast emulation from an integer constant. The second patch adds vec_duplicate<mode> expander and updates move expanders to convert the CONST_WIDE_INT and CONST_VECTO operands to vector broadcast from an integer with AVX2. H.J. Lu (2): Allow vec_duplicate_optab to fail x86: Convert CONST_WIDE_INT/CONST_VECTOR to broadcast gcc/config/i386/i386-expand.c | 216 +++++++++++++++++- gcc/config/i386/i386-protos.h | 3 + gcc/config/i386/i386.c | 31 +++ gcc/config/i386/sse.md | 19 ++ gcc/doc/md.texi | 2 - gcc/expr.c | 10 +- .../i386/avx512f-broadcast-pr87767-1.c | 7 +- .../i386/avx512f-broadcast-pr87767-5.c | 5 +- .../gcc.target/i386/avx512f_cond_move.c | 4 +- .../i386/avx512vl-broadcast-pr87767-1.c | 12 +- .../i386/avx512vl-broadcast-pr87767-5.c | 9 +- gcc/testsuite/gcc.target/i386/pr100865-1.c | 13 ++ gcc/testsuite/gcc.target/i386/pr100865-10a.c | 33 +++ gcc/testsuite/gcc.target/i386/pr100865-10b.c | 7 + gcc/testsuite/gcc.target/i386/pr100865-2.c | 14 ++ gcc/testsuite/gcc.target/i386/pr100865-3.c | 15 ++ gcc/testsuite/gcc.target/i386/pr100865-4a.c | 16 ++ gcc/testsuite/gcc.target/i386/pr100865-4b.c | 9 + gcc/testsuite/gcc.target/i386/pr100865-5a.c | 16 ++ gcc/testsuite/gcc.target/i386/pr100865-5b.c | 9 + gcc/testsuite/gcc.target/i386/pr100865-6a.c | 16 ++ gcc/testsuite/gcc.target/i386/pr100865-6b.c | 9 + gcc/testsuite/gcc.target/i386/pr100865-7a.c | 17 ++ gcc/testsuite/gcc.target/i386/pr100865-7b.c | 9 + gcc/testsuite/gcc.target/i386/pr100865-8a.c | 24 ++ gcc/testsuite/gcc.target/i386/pr100865-8b.c | 7 + gcc/testsuite/gcc.target/i386/pr100865-9a.c | 25 ++ gcc/testsuite/gcc.target/i386/pr100865-9b.c | 7 + 28 files changed, 534 insertions(+), 30 deletions(-) create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-1.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-10a.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-10b.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-2.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-3.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-4a.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-4b.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-5a.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-5b.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-6a.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-6b.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-7a.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-7b.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-8a.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-8b.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-9a.c create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-9b.c -- 2.31.1
