https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114440
--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Feng Xue <f...@gcc.gnu.org>: https://gcc.gnu.org/g:178cc419512f7e358f88dfe2336625aa99cd7438 commit r15-2096-g178cc419512f7e358f88dfe2336625aa99cd7438 Author: Feng Xue <f...@os.amperecomputing.com> Date: Wed May 29 17:22:36 2024 +0800 vect: Support multiple lane-reducing operations for loop reduction [PR114440] For lane-reducing operation(dot-prod/widen-sum/sad) in loop reduction, current vectorizer could only handle the pattern if the reduction chain does not contain other operation, no matter the other is normal or lane-reducing. This patches removes some constraints in reduction analysis to allow multiple arbitrary lane-reducing operations with mixed input vectypes in a loop reduction chain. For example: int sum = 1; for (i) { sum += d0[i] * d1[i]; // dot-prod <vector(16) char> sum += w[i]; // widen-sum <vector(16) char> sum += abs(s0[i] - s1[i]); // sad <vector(8) short> } The vector size is 128-bit vectorization factor is 16. Reduction statements would be transformed as: vector<4> int sum_v0 = { 0, 0, 0, 1 }; vector<4> int sum_v1 = { 0, 0, 0, 0 }; vector<4> int sum_v2 = { 0, 0, 0, 0 }; vector<4> int sum_v3 = { 0, 0, 0, 0 }; for (i / 16) { sum_v0 = DOT_PROD (d0_v0[i: 0 ~ 15], d1_v0[i: 0 ~ 15], sum_v0); sum_v1 = sum_v1; // copy sum_v2 = sum_v2; // copy sum_v3 = sum_v3; // copy sum_v0 = WIDEN_SUM (w_v0[i: 0 ~ 15], sum_v0); sum_v1 = sum_v1; // copy sum_v2 = sum_v2; // copy sum_v3 = sum_v3; // copy sum_v0 = SAD (s0_v0[i: 0 ~ 7 ], s1_v0[i: 0 ~ 7 ], sum_v0); sum_v1 = SAD (s0_v1[i: 8 ~ 15], s1_v1[i: 8 ~ 15], sum_v1); sum_v2 = sum_v2; // copy sum_v3 = sum_v3; // copy } sum_v = sum_v0 + sum_v1 + sum_v2 + sum_v3; // = sum_v0 + sum_v1 2024-03-22 Feng Xue <f...@os.amperecomputing.com> gcc/ PR tree-optimization/114440 * tree-vectorizer.h (vectorizable_lane_reducing): New function declaration. * tree-vect-stmts.cc (vect_analyze_stmt): Call new function vectorizable_lane_reducing to analyze lane-reducing operation. * tree-vect-loop.cc (vect_model_reduction_cost): Remove cost computation code related to emulated_mixed_dot_prod. (vectorizable_lane_reducing): New function. (vectorizable_reduction): Allow multiple lane-reducing operations in loop reduction. Move some original lane-reducing related code to vectorizable_lane_reducing. (vect_transform_reduction): Adjust comments with updated example. gcc/testsuite/ PR tree-optimization/114440 * gcc.dg/vect/vect-reduc-chain-1.c * gcc.dg/vect/vect-reduc-chain-2.c * gcc.dg/vect/vect-reduc-chain-3.c * gcc.dg/vect/vect-reduc-chain-dot-slp-1.c * gcc.dg/vect/vect-reduc-chain-dot-slp-2.c * gcc.dg/vect/vect-reduc-chain-dot-slp-3.c * gcc.dg/vect/vect-reduc-chain-dot-slp-4.c * gcc.dg/vect/vect-reduc-dot-slp-1.c
