From 7b1ff60122fda6e106e54b792713f8eb16424cf2 Mon Sep 17 00:00:00 2001 From: Jeff Law Date: Mon, 10 Dec 2018 21:56:54 -0700 Subject: [PATCH] re PR tree-optimization/80520 (Performance regression from missing if-conversion) PR tree-optimization/80520 * gimple-ssa-split-paths.c (is_feasible_trace): Recognize half diamonds that are likely if convertable. * gcc.dg/tree-ssa/split-path-5.c: Update expected output. * gcc.dg/tree-ssa/split-path-11.c: New test. From-SVN: r266971 --- gcc/ChangeLog | 6 ++ gcc/gimple-ssa-split-paths.c | 92 +++++++++++++++++++ gcc/testsuite/ChangeLog | 6 ++ gcc/testsuite/gcc.dg/tree-ssa/split-path-11.c | 14 +++ gcc/testsuite/gcc.dg/tree-ssa/split-path-5.c | 2 +- 5 files changed, 119 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/split-path-11.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 14c52ad64be..eddcdc3f843 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2018-12-10 Jeff Law + + PR tree-optimization/80520 + * gimple-ssa-split-paths.c (is_feasible_trace): Recognize half + diamonds that are likely if convertable. + 2018-12-10 Martin Sebor PR tree-optimization/86196 diff --git a/gcc/gimple-ssa-split-paths.c b/gcc/gimple-ssa-split-paths.c index a8515119ce5..91596526045 100644 --- a/gcc/gimple-ssa-split-paths.c +++ b/gcc/gimple-ssa-split-paths.c @@ -203,6 +203,98 @@ is_feasible_trace (basic_block bb) } } + /* Canonicalize the form. */ + if (num_stmts_in_pred1 == 0 && num_stmts_in_pred2 == 1) + { + std::swap (pred1, pred2); + std::swap (num_stmts_in_pred1, num_stmts_in_pred2); + } + + /* Another variant. This one is half-diamond. */ + if (num_stmts_in_pred1 == 1 && num_stmts_in_pred2 == 0 + && dominated_by_p (CDI_DOMINATORS, pred1, pred2)) + { + gimple *stmt1 = last_and_only_stmt (pred1); + + /* The only statement in PRED1 must be an assignment that is + not a good candidate for if-conversion. This may need some + generalization. */ + if (stmt1 && gimple_code (stmt1) == GIMPLE_ASSIGN) + { + enum tree_code code1 = gimple_assign_rhs_code (stmt1); + + if (!poor_ifcvt_candidate_code (code1)) + { + tree lhs1 = gimple_assign_lhs (stmt1); + tree rhs1 = gimple_assign_rhs1 (stmt1); + + gimple_stmt_iterator gsi; + for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + gimple *phi = gsi_stmt (gsi); + if ((gimple_phi_arg_def (phi, 0) == lhs1 + && gimple_phi_arg_def (phi, 1) == rhs1) + || (gimple_phi_arg_def (phi, 1) == lhs1 + && gimple_phi_arg_def (phi, 0) == rhs1)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, + "Block %d appears to be a join point for " + "if-convertable half-diamond.\n", + bb->index); + return false; + } + } + } + } + } + + /* Canonicalize the form. */ + if (num_stmts_in_pred1 == 0 && num_stmts_in_pred2 == 1) + { + std::swap (pred1, pred2); + std::swap (num_stmts_in_pred1, num_stmts_in_pred2); + } + + /* Another variant. This one is half-diamond. */ + if (num_stmts_in_pred1 == 1 && num_stmts_in_pred2 == 0 + && dominated_by_p (CDI_DOMINATORS, pred1, pred2)) + { + gimple *stmt1 = last_and_only_stmt (pred1); + + /* The only statement in PRED1 must be an assignment that is + not a good candidate for if-conversion. This may need some + generalization. */ + if (stmt1 && gimple_code (stmt1) == GIMPLE_ASSIGN) + { + enum tree_code code1 = gimple_assign_rhs_code (stmt1); + + if (!poor_ifcvt_candidate_code (code1)) + { + tree lhs1 = gimple_assign_lhs (stmt1); + tree rhs1 = gimple_assign_rhs1 (stmt1); + + gimple_stmt_iterator gsi; + for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + gimple *phi = gsi_stmt (gsi); + if ((gimple_phi_arg_def (phi, 0) == lhs1 + && gimple_phi_arg_def (phi, 1) == rhs1) + || (gimple_phi_arg_def (phi, 1) == lhs1 + && gimple_phi_arg_def (phi, 0) == rhs1)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, + "Block %d appears to be a join point for " + "if-convertable half-diamond.\n", + bb->index); + return false; + } + } + } + } + } + /* If the joiner has no PHIs with useful uses there is zero chance of CSE/DCE/jump-threading possibilities exposed by duplicating it. */ bool found_useful_phi = false; diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 43675b9adb0..0fde3cb395a 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2018-12-10 Jeff Law + + PR tree-optimization/80520 + * gcc.dg/tree-ssa/split-path-5.c: Update expected output. + * gcc.dg/tree-ssa/split-path-11.c: New test. + 2018-12-10 Steven G. Kargl PR fortran/97922 diff --git a/gcc/testsuite/gcc.dg/tree-ssa/split-path-11.c b/gcc/testsuite/gcc.dg/tree-ssa/split-path-11.c new file mode 100644 index 00000000000..f94f1a84e2c --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/split-path-11.c @@ -0,0 +1,14 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fsplit-paths -fdump-tree-split-paths-details -w" } */ + +void foo(unsigned long *M) +{ + for (unsigned long k = 0; k < 227; ++k) + { + unsigned long y = + ((M[k] & 0xffffffff80000000) | (M[k + 1] & 0x7fffffff)); + M[k] = (M[k + 397] ^ (y >> 1) ^ ((y & 1) ? 2567483615 : 0)); + } +} + +/* { dg-final { scan-tree-dump-times "join point for if-convertable half-diamond" 1 "split-paths" } } */ diff --git a/gcc/testsuite/gcc.dg/tree-ssa/split-path-5.c b/gcc/testsuite/gcc.dg/tree-ssa/split-path-5.c index 95aabdaf6be..83141a716ed 100644 --- a/gcc/testsuite/gcc.dg/tree-ssa/split-path-5.c +++ b/gcc/testsuite/gcc.dg/tree-ssa/split-path-5.c @@ -41,4 +41,4 @@ bmhi_init (const char *pattern) } } -/* { dg-final { scan-tree-dump-times "Duplicating join block" 1 "split-paths" } } */ +/* { dg-final { scan-tree-dump-times "join point for if-convertable half-diamond" 1 "split-paths" } } */