Hello All: This patch improves code sinking pass to sink the blocks before calls in the use blocks or immediate dominator blocks that reduces register pressure.
Bootstrapped and regtested on powerpc64-linux-gnu. Thanks & Regards Ajit tree-ssa-sink: Improve code sinking pass. Code Sinking sinks the blocks after call. This increases register pressure for callee-saved registers. Improves code sinking before call in the use blocks or immediate dominator of use blocks. 2023-04-16 Ajit Kumar Agarwal <aagar...@linux.ibm.com> gcc/ChangeLog: * tree-ssa-sink.cc (statement_sink_location): Modifed to move statements before calls. (block_call_p): New function. (def_use_same_block): New function. (select_best_block): Add heuristics to select the best blocks in the immediate post dominator. gcc/testsuite/ChangeLog: * gcc.dg/tree-ssa/ssa-sink-20.c: New testcase. * gcc.dg/tree-ssa/ssa-sink-21.c: New testcase. --- gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-20.c | 16 +++ gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-21.c | 20 +++ gcc/tree-ssa-sink.cc | 134 +++++++++++++++++++- 3 files changed, 164 insertions(+), 6 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-20.c create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-21.c diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-20.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-20.c new file mode 100644 index 00000000000..716bc1f9257 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-20.c @@ -0,0 +1,16 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-sink -fdump-tree-optimized -fdump-tree-sink-stats" } */ + +void bar(); +int j; +void foo(int a, int b, int c, int d, int e, int f) +{ + int l; + l = a + b + c + d +e + f; + if (a != 5) + { + bar(); + j = l; + } +} +/* { dg-final { scan-tree-dump-times "Sunk statements: 5" 1 "sink" } } */ diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-21.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-21.c new file mode 100644 index 00000000000..ff41e2ea8ae --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-21.c @@ -0,0 +1,20 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-sink-stats -fdump-tree-sink-stats" } */ + +void bar(); +int j, x; +void foo(int a, int b, int c, int d, int e, int f) +{ + int l; + l = a + b + c + d +e + f; + if (a != 5) + { + bar(); + if (b != 3) + x = 3; + else + x = 5; + j = l; + } +} +/* { dg-final { scan-tree-dump-times "Sunk statements: 5" 1 "sink" } } */ diff --git a/gcc/tree-ssa-sink.cc b/gcc/tree-ssa-sink.cc index 87b1d40c174..12babf73321 100644 --- a/gcc/tree-ssa-sink.cc +++ b/gcc/tree-ssa-sink.cc @@ -171,6 +171,70 @@ nearest_common_dominator_of_uses (def_operand_p def_p, bool *debug_stmts) return commondom; } +/* Check def and use stmts are in same block. */ + +bool +def_use_same_block (gimple *use) +{ + use_operand_p use_p; + def_operand_p def_p; + imm_use_iterator imm_iter; + ssa_op_iter iter; + + FOR_EACH_SSA_DEF_OPERAND (def_p, use, iter, SSA_OP_DEF) + { + FOR_EACH_IMM_USE_FAST (use_p, imm_iter, DEF_FROM_PTR (def_p)) + { + if (is_gimple_debug (USE_STMT (use_p))) + continue; + + if (use_p + && (gimple_bb(USE_STMT (use_p)) == gimple_bb (use))) + return true; + } + } + return false; +} + +/* Check if the block has only calls. */ + +bool +block_call_p (basic_block bb) +{ + int i = 0; + bool is_call = false; + gimple_stmt_iterator gsi = gsi_last_bb (bb); + gimple *last_stmt = gsi_stmt (gsi); + + if (last_stmt && gimple_code (last_stmt) == GIMPLE_COND) + { + if (!gsi_end_p (gsi)) + gsi_prev (&gsi); + + for (; !gsi_end_p (gsi);) + { + gimple *stmt = gsi_stmt (gsi); + + if (is_gimple_debug (stmt)) + return false; + + if (is_gimple_call (stmt)) + is_call = true; + else + return false; + + if (!gsi_end_p (gsi)) + gsi_prev (&gsi); + + ++i; + } + } + if (is_call && i == 1) + return true; + + return false; +} + /* Given EARLY_BB and LATE_BB, two blocks in a path through the dominator tree, return the best basic block between them (inclusive) to place statements. @@ -190,7 +254,8 @@ nearest_common_dominator_of_uses (def_operand_p def_p, bool *debug_stmts) static basic_block select_best_block (basic_block early_bb, basic_block late_bb, - gimple *stmt) + gimple *stmt, + gimple *use = 0) { basic_block best_bb = late_bb; basic_block temp_bb = late_bb; @@ -230,7 +295,28 @@ select_best_block (basic_block early_bb, if (threshold > 100) threshold = 100; } + if (bb_loop_depth (best_bb) == bb_loop_depth (early_bb) + && !(best_bb->count * 100 >= early_bb->count * threshold)) + { + basic_block new_best_bb = get_immediate_dominator (CDI_DOMINATORS, best_bb); + + if (new_best_bb && use + && (new_best_bb != best_bb) + && (new_best_bb != early_bb) + && !is_gimple_call (stmt) + && gsi_end_p (gsi_start_phis (new_best_bb)) + && (gimple_bb (use) != early_bb) + && !is_gimple_call (use) + && dominated_by_p (CDI_POST_DOMINATORS, new_best_bb, gimple_bb(use)) + && dominated_by_p (CDI_DOMINATORS, new_best_bb, early_bb) + && block_call_p (new_best_bb)) + { + if (def_use_same_block (use)) + return best_bb; + return new_best_bb; + } + } /* If BEST_BB is at the same nesting level, then require it to have significantly lower execution frequency to avoid gratuitous movement. */ if (bb_loop_depth (best_bb) == bb_loop_depth (early_bb) @@ -456,19 +542,55 @@ statement_sink_location (gimple *stmt, basic_block frombb, continue; break; } + use = USE_STMT (one_use); if (gimple_code (use) != GIMPLE_PHI) { - sinkbb = select_best_block (frombb, gimple_bb (use), stmt); + sinkbb = select_best_block (frombb, gimple_bb (use), stmt, use); if (sinkbb == frombb) return false; - if (sinkbb == gimple_bb (use)) - *togsi = gsi_for_stmt (use); - else - *togsi = gsi_after_labels (sinkbb); + gimple *def_stmt = SSA_NAME_DEF_STMT (DEF_FROM_PTR (def_p)); + + if ((gimple_bb (def_stmt) == gimple_bb (use)) + && (gimple_bb (use) != sinkbb)) + sinkbb = gimple_bb (use); + + if (sinkbb == gimple_bb (use)) + { + gimple_stmt_iterator gsi = gsi_last_bb (sinkbb); + gimple *def_stmt = SSA_NAME_DEF_STMT (DEF_FROM_PTR (def_p)); + gimple *last_stmt = gsi_stmt (gsi); + + if (gsi_stmt (gsi) == use + && !is_gimple_call (last_stmt) + && (gimple_code (last_stmt) != GIMPLE_SWITCH) + && (gimple_code (last_stmt) != GIMPLE_COND) + && (gimple_code (last_stmt) != GIMPLE_GOTO) + && (!gimple_vdef (use) || !def_use_same_block (def_stmt))) + { + if (!gsi_end_p (gsi)) + gsi_prev (&gsi); + + gimple *stmt = gsi_stmt (gsi); + + if (!gsi_end_p (gsi)) + gsi_prev (&gsi); + + if (gsi_end_p (gsi) && stmt && is_gimple_call (stmt) + && gsi_end_p (gsi_start_phis (sinkbb)) + && !is_gimple_call (def_stmt)) + *togsi = gsi_for_stmt (stmt); + else + *togsi = gsi_for_stmt (use); + } + else + *togsi = gsi_for_stmt(use); + } + else + *togsi = gsi_after_labels (sinkbb); return true; } -- 2.31.1