| Message ID | 874lnmx78a.fsf@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Two fixes for live-out SLP inductions (PR 83857) | expand |
On Tue, Jan 16, 2018 at 2:29 PM, Richard Sandiford <richard.sandiford@linaro.org> wrote: > vect_analyze_loop_operations was calling vectorizable_live_operation > for all live-out phis, which led to a bogus ncopies calculation in > the pure SLP case. I think v_a_l_o should only be passing phis > that are vectorised using normal loop vectorisation, since > vect_slp_analyze_node_operations handles the SLP side (and knows > the correct slp_index and slp_node arguments to pass in, via > vect_analyze_stmt). > > With that fixed we hit an older bug that vectorizable_live_operation > didn't handle live-out SLP inductions. Fixed by using gimple_phi_result > rather than gimple_get_lhs for phis. > > Tested on aarch64-linux-gnu. OK to install? Ok. Richard. > Richard > > > 2018-01-16 Richard Sandiford <richard.sandiford@linaro.org> > > gcc/ > PR tree-optimization/83857 > * tree-vect-loop.c (vect_analyze_loop_operations): Don't call > vectorizable_live_operation for pure SLP statements. > (vectorizable_live_operation): Handle PHIs. > > gcc/testsuite/ > PR tree-optimization/83857 > * gcc.dg/vect/pr83857.c: New test. > > Index: gcc/tree-vect-loop.c > =================================================================== > --- gcc/tree-vect-loop.c 2018-01-13 18:02:00.950360196 +0000 > +++ gcc/tree-vect-loop.c 2018-01-16 13:24:33.022528019 +0000 > @@ -1851,7 +1851,10 @@ vect_analyze_loop_operations (loop_vec_i > ok = vectorizable_reduction (phi, NULL, NULL, NULL, NULL); > } > > - if (ok && STMT_VINFO_LIVE_P (stmt_info)) > + /* SLP PHIs are tested by vect_slp_analyze_node_operations. */ > + if (ok > + && STMT_VINFO_LIVE_P (stmt_info) > + && !PURE_SLP_STMT (stmt_info)) > ok = vectorizable_live_operation (phi, NULL, NULL, -1, NULL); > > if (!ok) > @@ -8217,7 +8220,11 @@ vectorizable_live_operation (gimple *stm > gcc_assert (!LOOP_VINFO_FULLY_MASKED_P (loop_vinfo)); > > /* Get the correct slp vectorized stmt. */ > - vec_lhs = gimple_get_lhs (SLP_TREE_VEC_STMTS (slp_node)[vec_entry]); > + gimple *vec_stmt = SLP_TREE_VEC_STMTS (slp_node)[vec_entry]; > + if (gphi *phi = dyn_cast <gphi *> (vec_stmt)) > + vec_lhs = gimple_phi_result (phi); > + else > + vec_lhs = gimple_get_lhs (vec_stmt); > > /* Get entry to use. */ > bitstart = bitsize_int (vec_index); > Index: gcc/testsuite/gcc.dg/vect/pr83857.c > =================================================================== > --- /dev/null 2018-01-15 18:48:25.844002736 +0000 > +++ gcc/testsuite/gcc.dg/vect/pr83857.c 2018-01-16 13:24:33.021528058 +0000 > @@ -0,0 +1,30 @@ > +/* { dg-do run } */ > +/* { dg-additional-options "-ffast-math" } */ > + > +#define N 100 > + > +double __attribute__ ((noinline, noclone)) > +f (double *x, double y) > +{ > + double a = 0; > + for (int i = 0; i < N; ++i) > + { > + a += y; > + x[i * 2] += a; > + x[i * 2 + 1] += a; > + } > + return a - y; > +} > + > +double x[N * 2]; > + > +int > +main (void) > +{ > + if (f (x, 5) != (N - 1) * 5) > + __builtin_abort (); > + return 0; > +} > + > +/* { dg-final { scan-tree-dump "Loop contains only SLP stmts" "vect" { target vect_double } } } */ > +/* { dg-final { scan-tree-dump "vectorized 1 loops" "vect" { target vect_double } } } */
Index: gcc/tree-vect-loop.c =================================================================== --- gcc/tree-vect-loop.c 2018-01-13 18:02:00.950360196 +0000 +++ gcc/tree-vect-loop.c 2018-01-16 13:24:33.022528019 +0000 @@ -1851,7 +1851,10 @@ vect_analyze_loop_operations (loop_vec_i ok = vectorizable_reduction (phi, NULL, NULL, NULL, NULL); } - if (ok && STMT_VINFO_LIVE_P (stmt_info)) + /* SLP PHIs are tested by vect_slp_analyze_node_operations. */ + if (ok + && STMT_VINFO_LIVE_P (stmt_info) + && !PURE_SLP_STMT (stmt_info)) ok = vectorizable_live_operation (phi, NULL, NULL, -1, NULL); if (!ok) @@ -8217,7 +8220,11 @@ vectorizable_live_operation (gimple *stm gcc_assert (!LOOP_VINFO_FULLY_MASKED_P (loop_vinfo)); /* Get the correct slp vectorized stmt. */ - vec_lhs = gimple_get_lhs (SLP_TREE_VEC_STMTS (slp_node)[vec_entry]); + gimple *vec_stmt = SLP_TREE_VEC_STMTS (slp_node)[vec_entry]; + if (gphi *phi = dyn_cast <gphi *> (vec_stmt)) + vec_lhs = gimple_phi_result (phi); + else + vec_lhs = gimple_get_lhs (vec_stmt); /* Get entry to use. */ bitstart = bitsize_int (vec_index); Index: gcc/testsuite/gcc.dg/vect/pr83857.c =================================================================== --- /dev/null 2018-01-15 18:48:25.844002736 +0000 +++ gcc/testsuite/gcc.dg/vect/pr83857.c 2018-01-16 13:24:33.021528058 +0000 @@ -0,0 +1,30 @@ +/* { dg-do run } */ +/* { dg-additional-options "-ffast-math" } */ + +#define N 100 + +double __attribute__ ((noinline, noclone)) +f (double *x, double y) +{ + double a = 0; + for (int i = 0; i < N; ++i) + { + a += y; + x[i * 2] += a; + x[i * 2 + 1] += a; + } + return a - y; +} + +double x[N * 2]; + +int +main (void) +{ + if (f (x, 5) != (N - 1) * 5) + __builtin_abort (); + return 0; +} + +/* { dg-final { scan-tree-dump "Loop contains only SLP stmts" "vect" { target vect_double } } } */ +/* { dg-final { scan-tree-dump "vectorized 1 loops" "vect" { target vect_double } } } */