https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112554
--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Lehua Ding <lh...@gcc.gnu.org>: https://gcc.gnu.org/g:fc6f7ab4e078aaf52c37739da73eb6416f5ec788 commit r14-5516-gfc6f7ab4e078aaf52c37739da73eb6416f5ec788 Author: Juzhe-Zhong <juzhe.zh...@rivai.ai> Date: Thu Nov 16 10:58:16 2023 +0800 VECT: Clear LOOP_VINFO_USING_SELECT_VL_P when loop is not partial vectorized This patch fixes ICE: https://godbolt.org/z/z8T6o6qov <source>: In function 'b': <source>:2:6: error: missing definition 2 | void b() { | ^ for SSA_NAME: loop_len_8 in statement: _1 = -loop_len_8; during GIMPLE pass: vect <source>:2:6: internal compiler error: verify_ssa failed 0x7f1b56331082 __libc_start_main ???:0 Please submit a full bug report, with preprocessed source (by using -freport-bug). Please include the complete backtrace with any bug report. See <https://gcc.gnu.org/bugs/> for instructions. Compiler returned: 1 The root cause is we generate such IR in vectorization: _1 = -loop_len_8; vect_cst__11 = {_1, _1}; _18 = vect_vec_iv_.6_14 + vect_cst__11; loop_len_8 is uninitialized value. The IR _18 = vect_vec_iv_.6_14 + vect_cst__11; is generated because of we are adding induction variable with the result of SELECT_VL instead of VF. The code is: else if (LOOP_VINFO_USING_SELECT_VL_P (loop_vinfo)) { /* When we're using loop_len produced by SELEC_VL, the non-final iterations are not always processing VF elements. So vectorize induction variable instead of _21 = vect_vec_iv_.6_22 + { VF, ... }; We should generate: _35 = .SELECT_VL (ivtmp_33, VF); vect_cst__22 = [vec_duplicate_expr] _35; _21 = vect_vec_iv_.6_22 + vect_cst__22; */ gcc_assert (!slp_node); gimple_seq seq = NULL; vec_loop_lens *lens = &LOOP_VINFO_LENS (loop_vinfo); tree len = vect_get_loop_len (loop_vinfo, NULL, lens, 1, vectype, 0, 0); expr = force_gimple_operand (fold_convert (TREE_TYPE (step_expr), unshare_expr (len)), &seq, true, NULL_TREE); new_name = gimple_build (&seq, MULT_EXPR, TREE_TYPE (step_expr), expr, step_expr); gsi_insert_seq_before (&si, seq, GSI_SAME_STMT); step_iv_si = &si; } LOOP_VINFO_USING_SELECT_VL_P is set before loop vectorization analysis so we don't know whether it is partial vectorization or not but the induction variable depends on SELECT_VL_P is true. So update SELECT_VL_P as false when it is not partial vectorization. PR middle-end/112554 gcc/ChangeLog: * tree-vect-loop.cc (vect_determine_partial_vectors_and_peeling): Clear SELECT_VL_P for non-partial vectorization. gcc/testsuite/ChangeLog: * gcc.target/riscv/rvv/autovec/pr112554.c: New test.
