| Message ID | YiHV6KNNuxvnuoWq@tucnak |
|---|---|
| State | New |
| Headers | show |
| Series | gimplify: Clear TREE_READONLY on automatic vars being stored into [PR104529] | expand |
> Am 04.03.2022 um 10:04 schrieb Jakub Jelinek via Gcc-patches <gcc-patches@gcc.gnu.org>: > > Hi! > > The following testcase regressed when SRA started punting on stores to > TREE_READONLY vars. We document that: > "In a VAR_DECL, PARM_DECL or FIELD_DECL, or any kind of ..._REF node, > nonzero means it may not be the lhs of an assignment." > so the SRA change looks desirable. On the other side, at least in this > testcase the TREE_READONLY is set there intentionally from the > PR85873 fix, because gimplify_init_constructor itself uses TREE_READONLY > on the object to determine if it can perform promotion to static const > or not. > > So, similarly to other spots in the gimplifier where we also clear > TREE_READONLY when we emit IL that stores into the object, this > does the same in gimplify_init_constructor, but in the way so that > the TREE_READONLY test for the promotion to static const keeps working > and doesn't change anything for notify_temp_creation mode, which doesn't > emit any IL, just tests if it would need a temporary or not. > > This keeps PR85873 testcase working as before and fixes this regression. > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? Ok. Thanks, Richard > 2022-03-04 Jakub Jelinek <jakub@redhat.com> > > PR middle-end/104529 > * gimplify.cc (gimplify_init_constructor): Clear TREE_READONLY > on automatic objects which will be runtime initialized. > > * g++.dg/tree-ssa/pr104529.C: New test. > > --- gcc/gimplify.cc.jj 2022-03-03 09:13:16.000000000 +0100 > +++ gcc/gimplify.cc 2022-03-03 15:21:02.270198275 +0100 > @@ -5120,6 +5120,12 @@ gimplify_init_constructor (tree *expr_p, > { > if (notify_temp_creation) > return GS_OK; > + > + /* The var will be initialized and so appear on lhs of > + assignment, it can't be TREE_READONLY anymore. */ > + if (VAR_P (object)) > + TREE_READONLY (object) = 0; > + > is_empty_ctor = true; > break; > } > @@ -5171,6 +5177,11 @@ gimplify_init_constructor (tree *expr_p, > break; > } > > + /* The var will be initialized and so appear on lhs of > + assignment, it can't be TREE_READONLY anymore. */ > + if (VAR_P (object) && !notify_temp_creation) > + TREE_READONLY (object) = 0; > + > /* If there are "lots" of initialized elements, even discounting > those that are not address constants (and thus *must* be > computed at runtime), then partition the constructor into > --- gcc/testsuite/g++.dg/tree-ssa/pr104529.C.jj 2022-03-03 14:57:30.216939375 +0100 > +++ gcc/testsuite/g++.dg/tree-ssa/pr104529.C 2022-03-03 14:57:23.002040380 +0100 > @@ -0,0 +1,20 @@ > +// PR middle-end/104529 > +// { dg-do compile { target c++11 } } > +// { dg-options "-O2 -fdump-tree-optimized" } > +// { dg-final { scan-tree-dump-not "MEM\[^\n\r]*MEM" "optimized" } } > + > +#include <cstddef> > +#include <vector> > + > +struct S { > + unsigned int a; > + std::vector<unsigned char> b; > + std::vector<unsigned char> c; > +}; > + > +std::size_t > +foo () > +{ > + S test[] = { { 48, { 255, 0, 0, 0, 0, 0 } } }; > + return sizeof (test); > +} > > Jakub >
--- gcc/gimplify.cc.jj 2022-03-03 09:13:16.000000000 +0100 +++ gcc/gimplify.cc 2022-03-03 15:21:02.270198275 +0100 @@ -5120,6 +5120,12 @@ gimplify_init_constructor (tree *expr_p, { if (notify_temp_creation) return GS_OK; + + /* The var will be initialized and so appear on lhs of + assignment, it can't be TREE_READONLY anymore. */ + if (VAR_P (object)) + TREE_READONLY (object) = 0; + is_empty_ctor = true; break; } @@ -5171,6 +5177,11 @@ gimplify_init_constructor (tree *expr_p, break; } + /* The var will be initialized and so appear on lhs of + assignment, it can't be TREE_READONLY anymore. */ + if (VAR_P (object) && !notify_temp_creation) + TREE_READONLY (object) = 0; + /* If there are "lots" of initialized elements, even discounting those that are not address constants (and thus *must* be computed at runtime), then partition the constructor into --- gcc/testsuite/g++.dg/tree-ssa/pr104529.C.jj 2022-03-03 14:57:30.216939375 +0100 +++ gcc/testsuite/g++.dg/tree-ssa/pr104529.C 2022-03-03 14:57:23.002040380 +0100 @@ -0,0 +1,20 @@ +// PR middle-end/104529 +// { dg-do compile { target c++11 } } +// { dg-options "-O2 -fdump-tree-optimized" } +// { dg-final { scan-tree-dump-not "MEM\[^\n\r]*MEM" "optimized" } } + +#include <cstddef> +#include <vector> + +struct S { + unsigned int a; + std::vector<unsigned char> b; + std::vector<unsigned char> c; +}; + +std::size_t +foo () +{ + S test[] = { { 48, { 255, 0, 0, 0, 0, 0 } } }; + return sizeof (test); +}