https://gcc.gnu.org/g:1f7bb5c73d588dd5da92d8673d0583a8431a81c5
commit r16-6498-g1f7bb5c73d588dd5da92d8673d0583a8431a81c5 Author: Pan Li <[email protected]> Date: Sun Dec 28 16:33:27 2025 +0800 Vect: Adjust depth_limit of vec_slp_has_scalar_use from 2 to 3 The test case of RISC-V vx-6-u8.c is failed for the vaaddu.vx asm check when --param=gpr2vr-cost=2 recently. After some investigation, it is failed to vectorize afte some middle-end changes. The depth_limit is 2 of the func vec_slp_has_scalar_use, and then return -1 by design. Then the slp_insntance got 12 in size and we may see log similar as below: *_2 1 times vec_to_scalar costs 3 in epilogue *_2 1 times vec_to_scalar costs 3 in epilogue *_2 1 times vec_to_scalar costs 3 in epilogue *_2 1 times vec_to_scalar costs 3 in epilogue Vector cost: 18 Scalar cost: 9 And then cannot vectorize due to cost consideration. This PATCH would like to adjust the depth_limit to 3 suggested by Richard. gcc/ChangeLog: * tree-vect-slp.cc (vec_slp_has_scalar_use): Adjust the depth_limit from 2 to 3. gcc/testsuite/ChangeLog: * gcc.target/riscv/rvv/autovec/sat_add-cost-1.c: New test. Signed-off-by: Pan Li <[email protected]> Diff: --- .../gcc.target/riscv/rvv/autovec/sat_add-cost-1.c | 59 ++++++++++++++++++++++ gcc/tree-vect-slp.cc | 2 +- 2 files changed, 60 insertions(+), 1 deletion(-) diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/sat_add-cost-1.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/sat_add-cost-1.c new file mode 100644 index 000000000000..6f9ef08d3c2a --- /dev/null +++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/sat_add-cost-1.c @@ -0,0 +1,59 @@ +/* { dg-do compile } */ +/* { dg-options "-march=rv64gcv_zvl128b -mabi=lp64d --param=gpr2vr-cost=2 -fdump-tree-optimized" } */ + +#include <stdint.h> + +#define T uint8_t + +T +test_sat_add (T a, T b) +{ + return (a + b) | (-(T)((T)(a + b) < a)); +} + +void +test_sat_add_cost_1 (T * restrict out, T * restrict in, + T x, unsigned n) +{ + unsigned k = 0; + T tmp = x + 3; + + while (k < n) + { + tmp = tmp ^ 0x82; + + out[k + 0] = test_sat_add (in[k + 0], tmp); + out[k + 1] = test_sat_add (in[k + 1], tmp); + k += 2; + + out[k + 0] = test_sat_add (in[k + 0], tmp); + out[k + 1] = test_sat_add (in[k + 1], tmp); + k += 2; + + out[k + 0] = test_sat_add (in[k + 0], tmp); + out[k + 1] = test_sat_add (in[k + 1], tmp); + k += 2; + + out[k + 0] = test_sat_add (in[k + 0], tmp); + out[k + 1] = test_sat_add (in[k + 1], tmp); + k += 2; + + out[k + 0] = test_sat_add (in[k + 0], tmp); + out[k + 1] = test_sat_add (in[k + 1], tmp); + k += 2; + + out[k + 0] = test_sat_add (in[k + 0], tmp); + out[k + 1] = test_sat_add (in[k + 1], tmp); + k += 2; + + out[k + 0] = test_sat_add (in[k + 0], tmp); + out[k + 1] = test_sat_add (in[k + 1], tmp); + k += 2; + + out[k + 0] = test_sat_add (in[k + 0], tmp); + out[k + 1] = test_sat_add (in[k + 1], tmp); + k += 2; + } +} + +/* { dg-final { scan-tree-dump ".SAT_ADD " "optimized" } } */ diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc index c7b71342ffc4..4e01adf4cd30 100644 --- a/gcc/tree-vect-slp.cc +++ b/gcc/tree-vect-slp.cc @@ -8888,7 +8888,7 @@ vec_slp_has_scalar_use (bb_vec_info bb_vinfo, tree def, hash_map<tree, int> &scalar_use_map, int depth = 0) { - const int depth_limit = 2; + const int depth_limit = 3; imm_use_iterator use_iter; gimple *use_stmt;
