| Message ID | ri6mu9fj3dz.fsf@suse.cz |
|---|---|
| State | New |
| Headers | show |
| Series | sra: Avoid totally scalarizing overallping field_decls (PR93667) | expand |
On February 18, 2020 4:56:08 PM GMT+01:00, Martin Jambor <mjambor@suse.cz> wrote: >Hi, > >[[no_unique_address]] C++ attribute can cause two fields of a >RECORD_TYPE overlap, which currently confuses the totally scalarizing >code into creating invalid access tree. For GCC 10, I'd like to >simply disable total scalarization of types where this happens. > >For GCC 11 I'll write down a TODO item to enable total scalarization >of cases like this where the problematic fields are basically empty - >despite having a non-zero size - i.e. when they are just RECORD_TYPEs >without any data fields. > >Bootstrapped and tested on x86_64, OK for trunk? Ok. Richard. >Thanks, > >Martin > >2020-02-14 Martin Jambor <mjambor@suse.cz> > > PR tree-optimization/93667 > * tree-sra.c (scalarizable_type_p): Return false if record fields > do not follow wach other. > > testsuite/ > * g++.dg/tree-ssa/pr93667.C: New test. >--- > gcc/ChangeLog | 6 ++++++ > gcc/testsuite/ChangeLog | 5 +++++ > gcc/testsuite/g++.dg/tree-ssa/pr93667.C | 11 +++++++++++ > gcc/tree-sra.c | 14 ++++++++++++++ > 4 files changed, 36 insertions(+) > create mode 100644 gcc/testsuite/g++.dg/tree-ssa/pr93667.C > >diff --git a/gcc/testsuite/g++.dg/tree-ssa/pr93667.C >b/gcc/testsuite/g++.dg/tree-ssa/pr93667.C >new file mode 100644 >index 00000000000..d875f53d9ec >--- /dev/null >+++ b/gcc/testsuite/g++.dg/tree-ssa/pr93667.C >@@ -0,0 +1,11 @@ >+// { dg-do compile } >+// { dg-options "-O2 -std=c++2a" } */ >+ >+struct a {}; >+struct b { [[no_unique_address]] a aq; }; >+struct c { >+ int d; >+ [[no_unique_address]] b e; >+}; >+c f() {return {};} >+void g() { f(); } >diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c >index 0cfac0a8192..4c7d651e6b9 100644 >--- a/gcc/tree-sra.c >+++ b/gcc/tree-sra.c >@@ -958,6 +958,9 @@ scalarizable_type_p (tree type, bool const_decl) > if (type_contains_placeholder_p (type)) > return false; > >+ bool have_predecessor_field = false; >+ HOST_WIDE_INT prev_pos = 0; >+ > switch (TREE_CODE (type)) > { > case RECORD_TYPE: >@@ -966,6 +969,17 @@ scalarizable_type_p (tree type, bool const_decl) > { > tree ft = TREE_TYPE (fld); > >+ if (zerop (DECL_SIZE (fld))) >+ continue; >+ >+ HOST_WIDE_INT pos = int_bit_position (fld); >+ if (have_predecessor_field >+ && pos <= prev_pos) >+ return false; >+ >+ have_predecessor_field = true; >+ prev_pos = pos; >+ > if (DECL_BIT_FIELD (fld)) > return false; >
diff --git a/gcc/testsuite/g++.dg/tree-ssa/pr93667.C b/gcc/testsuite/g++.dg/tree-ssa/pr93667.C new file mode 100644 index 00000000000..d875f53d9ec --- /dev/null +++ b/gcc/testsuite/g++.dg/tree-ssa/pr93667.C @@ -0,0 +1,11 @@ +// { dg-do compile } +// { dg-options "-O2 -std=c++2a" } */ + +struct a {}; +struct b { [[no_unique_address]] a aq; }; +struct c { + int d; + [[no_unique_address]] b e; +}; +c f() {return {};} +void g() { f(); } diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c index 0cfac0a8192..4c7d651e6b9 100644 --- a/gcc/tree-sra.c +++ b/gcc/tree-sra.c @@ -958,6 +958,9 @@ scalarizable_type_p (tree type, bool const_decl) if (type_contains_placeholder_p (type)) return false; + bool have_predecessor_field = false; + HOST_WIDE_INT prev_pos = 0; + switch (TREE_CODE (type)) { case RECORD_TYPE: @@ -966,6 +969,17 @@ scalarizable_type_p (tree type, bool const_decl) { tree ft = TREE_TYPE (fld); + if (zerop (DECL_SIZE (fld))) + continue; + + HOST_WIDE_INT pos = int_bit_position (fld); + if (have_predecessor_field + && pos <= prev_pos) + return false; + + have_predecessor_field = true; + prev_pos = pos; + if (DECL_BIT_FIELD (fld)) return false;