Re: [PATCH v5] tree-ssa-sink: Improve code sinking pass
On 23/06/23 7:44 am, Peter Bergner wrote: > On 6/1/23 11:54 PM, Ajit Agarwal via Gcc-patches wrote: >> >> >> On 01/06/23 2:06 pm, Bernhard Reutner-Fischer wrote: >>> On 1 June 2023 09:20:08 CEST, Ajit Agarwal wrote: Hello All: This patch improves code sinking pass to sink statements before call to reduce register pressure. Review comments are incorporated. >>> >>> Hi Ajit! >>> >>> I had two comments for v4 that you did not address in v5 or followed up. >>> thanks, >> >> Which comments I didn't address. Please let me know. > > I believe he's referring to these two comments: > > > + && dominated_by_p (CDI_DOMINATORS, new_best_bb, early_bb)) > > + { > > + if (def_use_same_block (use)) > > + return best_bb; > > + > > + return new_best_bb; > > + } > > + return best_bb; > > +} > > > > Many returns. > I'd have said > && !def_use_same_block (use) > return new_best_bb; > else > return best_bb; > > and rephrase the comment above list of Things to consider accordingly. > > > I agree with Bernhard's comment that it could be rewritten to be clearer. > Although, the "else" isn't really required. So Bernhard's version would > look like: > > 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) > && !def_use_same_block (use)) > return new_best_bb; > else > return best_bb; > > ...or just: > > 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) > && !def_use_same_block (use)) > return new_best_bb; > > return best_bb; > > > Either works. Thanks Peter. I will incorporate and send the new version of the patch. > > > Peter >
Re: [PATCH v5] tree-ssa-sink: Improve code sinking pass
On 6/1/23 11:54 PM, Ajit Agarwal via Gcc-patches wrote: > > > On 01/06/23 2:06 pm, Bernhard Reutner-Fischer wrote: >> On 1 June 2023 09:20:08 CEST, Ajit Agarwal wrote: >>> Hello All: >>> >>> This patch improves code sinking pass to sink statements before call to >>> reduce >>> register pressure. >>> Review comments are incorporated. >> >> Hi Ajit! >> >> I had two comments for v4 that you did not address in v5 or followed up. >> thanks, > > Which comments I didn't address. Please let me know. I believe he's referring to these two comments: > + && dominated_by_p (CDI_DOMINATORS, new_best_bb, early_bb)) > + { > + if (def_use_same_block (use)) > + return best_bb; > + > + return new_best_bb; > + } > + return best_bb; > +} > Many returns. I'd have said && !def_use_same_block (use) return new_best_bb; else return best_bb; and rephrase the comment above list of Things to consider accordingly. I agree with Bernhard's comment that it could be rewritten to be clearer. Although, the "else" isn't really required. So Bernhard's version would look like: 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) && !def_use_same_block (use)) return new_best_bb; else return best_bb; ...or just: 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) && !def_use_same_block (use)) return new_best_bb; return best_bb; Either works. Peter
Re: [PATCH v5] tree-ssa-sink: Improve code sinking pass
On 01/06/23 2:06 pm, Bernhard Reutner-Fischer wrote: > On 1 June 2023 09:20:08 CEST, Ajit Agarwal wrote: >> Hello All: >> >> This patch improves code sinking pass to sink statements before call to >> reduce >> register pressure. >> Review comments are incorporated. > > Hi Ajit! > > I had two comments for v4 that you did not address in v5 or followed up. > thanks, Which comments I didn't address. Please let me know. Thanks & Regards Ajit
Re: [PATCH v5] tree-ssa-sink: Improve code sinking pass
On 1 June 2023 09:20:08 CEST, Ajit Agarwal wrote: >Hello All: > >This patch improves code sinking pass to sink statements before call to reduce >register pressure. >Review comments are incorporated. Hi Ajit! I had two comments for v4 that you did not address in v5 or followed up. thanks,
[PATCH v5] tree-ssa-sink: Improve code sinking pass
Hello All: This patch improves code sinking pass to sink statements before call to reduce register pressure. Review comments are incorporated. For example : 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; } } Code Sinking does the following: void bar(); int j; void foo(int a, int b, int c, int d, int e, int f) { int l; if (a != 5) { l = a + b + c + d +e + f; bar(); j = l; } } Bootstrapped regtested on powerpc64-linux-gnu. Thanks & Regards Ajit tree-ssa-sink: Improve code sinking pass Currently, code sinking will sink code after function calls. This increases register pressure for callee-saved registers. The following patch improves code sinking by placing the sunk code before calls in the use block or in the immediate dominator of the use blocks. 2023-06-01 Ajit Kumar Agarwal gcc/ChangeLog: PR tree-optimization/81953 * tree-ssa-sink.cc (statement_sink_location): Move statements before calls. (def_use_same_block): New function. (select_best_block): Add heuristics to select the best blocks in the immediate post dominator. gcc/testsuite/ChangeLog: PR tree-optimization/81953 * 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 | 15 + gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-21.c | 19 ++ gcc/tree-ssa-sink.cc| 71 ++--- 3 files changed, 95 insertions(+), 10 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 000..d3b79ca5803 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-20.c @@ -0,0 +1,15 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -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 {l_12\s+=\s+_4\s+\+\s+f_11\(D\);\n\s+bar\s+\(\)} sink1 } } */ 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 000..84e7938c54f --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-21.c @@ -0,0 +1,19 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -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 {l_13\s+=\s+_4\s+\+\s+f_12\(D\);\n\s+bar\s+\(\)} sink1 } } */ diff --git a/gcc/tree-ssa-sink.cc b/gcc/tree-ssa-sink.cc index b1ba7a2ad6c..f1d25f1a0f8 100644 --- a/gcc/tree-ssa-sink.cc +++ b/gcc/tree-ssa-sink.cc @@ -171,9 +171,28 @@ nearest_common_dominator_of_uses (def_operand_p def_p, bool *debug_stmts) return commondom; } +/* Return TRUE if immediate uses of the defs in + STMT occur in the same block as STMT, FALSE otherwise. */ + +static bool +def_use_same_block (gimple *stmt) +{ + def_operand_p def; + ssa_op_iter iter; + + FOR_EACH_SSA_DEF_OPERAND (def, stmt, iter, SSA_OP_DEF) +{ + gimple *def_stmt = SSA_NAME_DEF_STMT (DEF_FROM_PTR (def)); + if ((gimple_bb (def_stmt) == gimple_bb (stmt))) + 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. + statements. The best basic block should be an immediate dominator of + best basic block if the use stmt is after the call. We want the most control dependent block in the shallowest loop nest. @@ -190,7 +209,8 @@ 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) { basic_block best_bb = late_bb; basic_block temp_bb = late_bb; @@ -237,7 +257,40 @@ select_best_block (basic_block early_bb, /* If result of comparsion is unknown, prefer EARLY_BB. Thus use !(...>=..) rather than (...<...) */ && !(best_bb->count * 100 >= early_bb->count * threshold)) -return best_bb; +{ + basic_block new_best_bb = get_immediate_dominator (CDI_DOMINATORS, best_bb); + /* Return best_bb if def and use are in same block otherwise new_best_bb. + +Things to consider: + + new_best_bb is not equal to best_bb