| Message ID | 20240514155132.2890624-1-quic_apinski@quicinc.com |
|---|---|
| State | New |
| Headers | show |
| Series | tree-cfg: Move the returns_twice check to be last statement only [PR114301] | expand |
On Tue, May 14, 2024 at 5:52 PM Andrew Pinski <quic_apinski@quicinc.com> wrote: > > When I was checking to making sure that all of the bugs dealing > with the case where gimple_can_duplicate_bb_p would return false was fixed, > I noticed that the code which was checking if a call statement was > returns_twice was checking all call statements rather than just the > last statement. Since calling gimple_call_flags has a small non-zero > overhead due to a few string comparison, removing the uses of it > can have a small performance improvement. In the case of returns_twice > functions calls, will always end the basic-block due to the check in > stmt_can_terminate_bb_p (and others). So checking only the last statement > is a small optimization and will be safe. > > Bootstrapped and tested pon x86_64-linux-gnu with no regressions. OK. > PR tree-optimization/114301 > gcc/ChangeLog: > > * tree-cfg.cc (gimple_can_duplicate_bb_p): Check returns_twice > only on the last call statement rather than all. > > Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com> > --- > gcc/tree-cfg.cc | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) > > diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc > index b2d47b72084..7fb7b92966b 100644 > --- a/gcc/tree-cfg.cc > +++ b/gcc/tree-cfg.cc > @@ -6495,6 +6495,13 @@ gimple_can_duplicate_bb_p (const_basic_block bb) > && gimple_call_internal_p (last) > && gimple_call_internal_unique_p (last)) > return false; > + > + /* Prohibit duplication of returns_twice calls, otherwise associated > + abnormal edges also need to be duplicated properly. > + return_twice functions will always be the last statement. */ > + if (is_gimple_call (last) > + && (gimple_call_flags (last) & ECF_RETURNS_TWICE)) > + return false; > } > > for (gimple_stmt_iterator gsi = gsi_start_bb (CONST_CAST_BB (bb)); > @@ -6502,15 +6509,12 @@ gimple_can_duplicate_bb_p (const_basic_block bb) > { > gimple *g = gsi_stmt (gsi); > > - /* Prohibit duplication of returns_twice calls, otherwise associated > - abnormal edges also need to be duplicated properly. > - An IFN_GOMP_SIMT_ENTER_ALLOC/IFN_GOMP_SIMT_EXIT call must be > + /* An IFN_GOMP_SIMT_ENTER_ALLOC/IFN_GOMP_SIMT_EXIT call must be > duplicated as part of its group, or not at all. > The IFN_GOMP_SIMT_VOTE_ANY and IFN_GOMP_SIMT_XCHG_* are part of such a > group, so the same holds there. */ > if (is_gimple_call (g) > - && (gimple_call_flags (g) & ECF_RETURNS_TWICE > - || gimple_call_internal_p (g, IFN_GOMP_SIMT_ENTER_ALLOC) > + && (gimple_call_internal_p (g, IFN_GOMP_SIMT_ENTER_ALLOC) > || gimple_call_internal_p (g, IFN_GOMP_SIMT_EXIT) > || gimple_call_internal_p (g, IFN_GOMP_SIMT_VOTE_ANY) > || gimple_call_internal_p (g, IFN_GOMP_SIMT_XCHG_BFLY) > -- > 2.34.1 >
diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc index b2d47b72084..7fb7b92966b 100644 --- a/gcc/tree-cfg.cc +++ b/gcc/tree-cfg.cc @@ -6495,6 +6495,13 @@ gimple_can_duplicate_bb_p (const_basic_block bb) && gimple_call_internal_p (last) && gimple_call_internal_unique_p (last)) return false; + + /* Prohibit duplication of returns_twice calls, otherwise associated + abnormal edges also need to be duplicated properly. + return_twice functions will always be the last statement. */ + if (is_gimple_call (last) + && (gimple_call_flags (last) & ECF_RETURNS_TWICE)) + return false; } for (gimple_stmt_iterator gsi = gsi_start_bb (CONST_CAST_BB (bb)); @@ -6502,15 +6509,12 @@ gimple_can_duplicate_bb_p (const_basic_block bb) { gimple *g = gsi_stmt (gsi); - /* Prohibit duplication of returns_twice calls, otherwise associated - abnormal edges also need to be duplicated properly. - An IFN_GOMP_SIMT_ENTER_ALLOC/IFN_GOMP_SIMT_EXIT call must be + /* An IFN_GOMP_SIMT_ENTER_ALLOC/IFN_GOMP_SIMT_EXIT call must be duplicated as part of its group, or not at all. The IFN_GOMP_SIMT_VOTE_ANY and IFN_GOMP_SIMT_XCHG_* are part of such a group, so the same holds there. */ if (is_gimple_call (g) - && (gimple_call_flags (g) & ECF_RETURNS_TWICE - || gimple_call_internal_p (g, IFN_GOMP_SIMT_ENTER_ALLOC) + && (gimple_call_internal_p (g, IFN_GOMP_SIMT_ENTER_ALLOC) || gimple_call_internal_p (g, IFN_GOMP_SIMT_EXIT) || gimple_call_internal_p (g, IFN_GOMP_SIMT_VOTE_ANY) || gimple_call_internal_p (g, IFN_GOMP_SIMT_XCHG_BFLY)
When I was checking to making sure that all of the bugs dealing with the case where gimple_can_duplicate_bb_p would return false was fixed, I noticed that the code which was checking if a call statement was returns_twice was checking all call statements rather than just the last statement. Since calling gimple_call_flags has a small non-zero overhead due to a few string comparison, removing the uses of it can have a small performance improvement. In the case of returns_twice functions calls, will always end the basic-block due to the check in stmt_can_terminate_bb_p (and others). So checking only the last statement is a small optimization and will be safe. Bootstrapped and tested pon x86_64-linux-gnu with no regressions. PR tree-optimization/114301 gcc/ChangeLog: * tree-cfg.cc (gimple_can_duplicate_bb_p): Check returns_twice only on the last call statement rather than all. Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com> --- gcc/tree-cfg.cc | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-)