Re: [PATCH] ipa: Avoid excessive removing of SSAs (PR 113757)
> On Thu, Feb 08 2024, Martin Jambor wrote: > > Hi, > > > > PR 113757 shows that the code which was meant to debug-reset and > > remove SSAs defined by LHSs of calls redirected to > > __builtin_unreachable can trigger also when speculative > > devirtualization creates a call to a noreturn function (and since it > > is noreturn, it does not bother dealing with its return value). > > > > What is more, it seems that the code handling this case is not really > > necessary. I feel slightly idiotic about this because I have a > > feeling that I added it because of a failing test-case but I can > > neither find the testcase nor a reason why the code in > > cgraph_edge::redirect_call_stmt_to_callee would not be sufficient (it > > turns the SSA name into a default-def, a bit like IPA-SRA, but any > > code dominated by a call to a noreturn is not dangerous when it comes > > to its side-effects). So this patch just removes the handling. > > > > Bootstrapped and tested on x86_64-linux and ppc64le-linux. I have also > > LTO-bootstrapped and LTO-profilebootstrapped the patch on x86_64-linux. > > > > OK for master? > > > > Thanks, > > > > Martin > > > > > > gcc/ChangeLog: > > > > 2024-02-07 Martin Jambor > > > > PR ipa/113757 > > * tree-inline.cc (redirect_all_calls): Remove code adding SSAs to > > id->killed_new_ssa_names. > > > > gcc/testsuite/ChangeLog: > > > > 2024-02-07 Martin Jambor > > > > PR ipa/113757 > > * g++.dg/ipa/pr113757.C: New test. OK, thanks! Honza > > --- > > gcc/testsuite/g++.dg/ipa/pr113757.C | 14 ++ > > gcc/tree-inline.cc | 14 ++ > > 2 files changed, 16 insertions(+), 12 deletions(-) > > create mode 100644 gcc/testsuite/g++.dg/ipa/pr113757.C > > > > diff --git a/gcc/testsuite/g++.dg/ipa/pr113757.C > > b/gcc/testsuite/g++.dg/ipa/pr113757.C > > new file mode 100644 > > index 000..885d4010a10 > > --- /dev/null > > +++ b/gcc/testsuite/g++.dg/ipa/pr113757.C > > @@ -0,0 +1,14 @@ > > +// { dg-do compile } > > +// { dg-options "-O2 -fPIC" } > > +// { dg-require-effective-target fpic } > > + > > +long size(); > > +struct ll { virtual int hh(); }; > > +ll *slice_owner; > > +int ll::hh() { __builtin_exit(0); } > > +int nn() { > > + if (size()) > > +return 0; > > + return slice_owner->hh(); > > +} > > +int (*a)() = nn; > > diff --git a/gcc/tree-inline.cc b/gcc/tree-inline.cc > > index 75c10eb7dfc..cac41b4f031 100644 > > --- a/gcc/tree-inline.cc > > +++ b/gcc/tree-inline.cc > > @@ -2984,23 +2984,13 @@ redirect_all_calls (copy_body_data * id, > > basic_block bb) > >gimple *stmt = gsi_stmt (si); > >if (is_gimple_call (stmt)) > > { > > - tree old_lhs = gimple_call_lhs (stmt); > > struct cgraph_edge *edge = id->dst_node->get_edge (stmt); > > if (edge) > > { > > if (!id->killed_new_ssa_names) > > id->killed_new_ssa_names = new hash_set (16); > > - gimple *new_stmt > > - = cgraph_edge::redirect_call_stmt_to_callee (edge, > > - id->killed_new_ssa_names); > > - if (old_lhs > > - && TREE_CODE (old_lhs) == SSA_NAME > > - && !gimple_call_lhs (new_stmt)) > > - /* In case of IPA-SRA removing the LHS, the name should have > > - been already added to the hash. But in case of redirecting > > - to builtin_unreachable it was not and the name still should > > - be pruned from debug statements. */ > > - id->killed_new_ssa_names->add (old_lhs); > > + cgraph_edge::redirect_call_stmt_to_callee (edge, > > + id->killed_new_ssa_names); > > > > if (stmt == last && id->call_stmt && maybe_clean_eh_stmt (stmt)) > > gimple_purge_dead_eh_edges (bb); > > -- > > 2.43.0
Re: [PATCH] ipa: Avoid excessive removing of SSAs (PR 113757)
Hello, and ping please. Martin On Thu, Feb 08 2024, Martin Jambor wrote: > Hi, > > PR 113757 shows that the code which was meant to debug-reset and > remove SSAs defined by LHSs of calls redirected to > __builtin_unreachable can trigger also when speculative > devirtualization creates a call to a noreturn function (and since it > is noreturn, it does not bother dealing with its return value). > > What is more, it seems that the code handling this case is not really > necessary. I feel slightly idiotic about this because I have a > feeling that I added it because of a failing test-case but I can > neither find the testcase nor a reason why the code in > cgraph_edge::redirect_call_stmt_to_callee would not be sufficient (it > turns the SSA name into a default-def, a bit like IPA-SRA, but any > code dominated by a call to a noreturn is not dangerous when it comes > to its side-effects). So this patch just removes the handling. > > Bootstrapped and tested on x86_64-linux and ppc64le-linux. I have also > LTO-bootstrapped and LTO-profilebootstrapped the patch on x86_64-linux. > > OK for master? > > Thanks, > > Martin > > > gcc/ChangeLog: > > 2024-02-07 Martin Jambor > > PR ipa/113757 > * tree-inline.cc (redirect_all_calls): Remove code adding SSAs to > id->killed_new_ssa_names. > > gcc/testsuite/ChangeLog: > > 2024-02-07 Martin Jambor > > PR ipa/113757 > * g++.dg/ipa/pr113757.C: New test. > --- > gcc/testsuite/g++.dg/ipa/pr113757.C | 14 ++ > gcc/tree-inline.cc | 14 ++ > 2 files changed, 16 insertions(+), 12 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/ipa/pr113757.C > > diff --git a/gcc/testsuite/g++.dg/ipa/pr113757.C > b/gcc/testsuite/g++.dg/ipa/pr113757.C > new file mode 100644 > index 000..885d4010a10 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/ipa/pr113757.C > @@ -0,0 +1,14 @@ > +// { dg-do compile } > +// { dg-options "-O2 -fPIC" } > +// { dg-require-effective-target fpic } > + > +long size(); > +struct ll { virtual int hh(); }; > +ll *slice_owner; > +int ll::hh() { __builtin_exit(0); } > +int nn() { > + if (size()) > +return 0; > + return slice_owner->hh(); > +} > +int (*a)() = nn; > diff --git a/gcc/tree-inline.cc b/gcc/tree-inline.cc > index 75c10eb7dfc..cac41b4f031 100644 > --- a/gcc/tree-inline.cc > +++ b/gcc/tree-inline.cc > @@ -2984,23 +2984,13 @@ redirect_all_calls (copy_body_data * id, basic_block > bb) >gimple *stmt = gsi_stmt (si); >if (is_gimple_call (stmt)) > { > - tree old_lhs = gimple_call_lhs (stmt); > struct cgraph_edge *edge = id->dst_node->get_edge (stmt); > if (edge) > { > if (!id->killed_new_ssa_names) > id->killed_new_ssa_names = new hash_set (16); > - gimple *new_stmt > - = cgraph_edge::redirect_call_stmt_to_callee (edge, > - id->killed_new_ssa_names); > - if (old_lhs > - && TREE_CODE (old_lhs) == SSA_NAME > - && !gimple_call_lhs (new_stmt)) > - /* In case of IPA-SRA removing the LHS, the name should have > -been already added to the hash. But in case of redirecting > -to builtin_unreachable it was not and the name still should > -be pruned from debug statements. */ > - id->killed_new_ssa_names->add (old_lhs); > + cgraph_edge::redirect_call_stmt_to_callee (edge, > + id->killed_new_ssa_names); > > if (stmt == last && id->call_stmt && maybe_clean_eh_stmt (stmt)) > gimple_purge_dead_eh_edges (bb); > -- > 2.43.0
[PATCH] ipa: Avoid excessive removing of SSAs (PR 113757)
Hi, PR 113757 shows that the code which was meant to debug-reset and remove SSAs defined by LHSs of calls redirected to __builtin_unreachable can trigger also when speculative devirtualization creates a call to a noreturn function (and since it is noreturn, it does not bother dealing with its return value). What is more, it seems that the code handling this case is not really necessary. I feel slightly idiotic about this because I have a feeling that I added it because of a failing test-case but I can neither find the testcase nor a reason why the code in cgraph_edge::redirect_call_stmt_to_callee would not be sufficient (it turns the SSA name into a default-def, a bit like IPA-SRA, but any code dominated by a call to a noreturn is not dangerous when it comes to its side-effects). So this patch just removes the handling. Bootstrapped and tested on x86_64-linux and ppc64le-linux. I have also LTO-bootstrapped and LTO-profilebootstrapped the patch on x86_64-linux. OK for master? Thanks, Martin gcc/ChangeLog: 2024-02-07 Martin Jambor PR ipa/113757 * tree-inline.cc (redirect_all_calls): Remove code adding SSAs to id->killed_new_ssa_names. gcc/testsuite/ChangeLog: 2024-02-07 Martin Jambor PR ipa/113757 * g++.dg/ipa/pr113757.C: New test. --- gcc/testsuite/g++.dg/ipa/pr113757.C | 14 ++ gcc/tree-inline.cc | 14 ++ 2 files changed, 16 insertions(+), 12 deletions(-) create mode 100644 gcc/testsuite/g++.dg/ipa/pr113757.C diff --git a/gcc/testsuite/g++.dg/ipa/pr113757.C b/gcc/testsuite/g++.dg/ipa/pr113757.C new file mode 100644 index 000..885d4010a10 --- /dev/null +++ b/gcc/testsuite/g++.dg/ipa/pr113757.C @@ -0,0 +1,14 @@ +// { dg-do compile } +// { dg-options "-O2 -fPIC" } +// { dg-require-effective-target fpic } + +long size(); +struct ll { virtual int hh(); }; +ll *slice_owner; +int ll::hh() { __builtin_exit(0); } +int nn() { + if (size()) +return 0; + return slice_owner->hh(); +} +int (*a)() = nn; diff --git a/gcc/tree-inline.cc b/gcc/tree-inline.cc index 75c10eb7dfc..cac41b4f031 100644 --- a/gcc/tree-inline.cc +++ b/gcc/tree-inline.cc @@ -2984,23 +2984,13 @@ redirect_all_calls (copy_body_data * id, basic_block bb) gimple *stmt = gsi_stmt (si); if (is_gimple_call (stmt)) { - tree old_lhs = gimple_call_lhs (stmt); struct cgraph_edge *edge = id->dst_node->get_edge (stmt); if (edge) { if (!id->killed_new_ssa_names) id->killed_new_ssa_names = new hash_set (16); - gimple *new_stmt - = cgraph_edge::redirect_call_stmt_to_callee (edge, - id->killed_new_ssa_names); - if (old_lhs - && TREE_CODE (old_lhs) == SSA_NAME - && !gimple_call_lhs (new_stmt)) - /* In case of IPA-SRA removing the LHS, the name should have - been already added to the hash. But in case of redirecting - to builtin_unreachable it was not and the name still should - be pruned from debug statements. */ - id->killed_new_ssa_names->add (old_lhs); + cgraph_edge::redirect_call_stmt_to_callee (edge, + id->killed_new_ssa_names); if (stmt == last && id->call_stmt && maybe_clean_eh_stmt (stmt)) gimple_purge_dead_eh_edges (bb); -- 2.43.0