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From: Jason Merrill <jason@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-5318] c++: TARGET_EXPR collapsing [PR107303] Date: Tue, 24 Jan 2023 03:26:30 +0000 (GMT) [thread overview] Message-ID: <20230124032631.04B7A3858C00@sourceware.org> (raw) https://gcc.gnu.org/g:049a52909075117f5112971cc83952af2a818bc1 commit r13-5318-g049a52909075117f5112971cc83952af2a818bc1 Author: Jason Merrill <jason@redhat.com> Date: Mon Jan 23 16:25:07 2023 -0500 c++: TARGET_EXPR collapsing [PR107303] In r13-2978 I tried to eliminate TARGET_EXPR around TARGET_EXPR by discarding the outer one, but as in this testcase that breaks if the TARGET_EXPR_SLOT of the outer one is used elsewhere. But it should always be safe to strip the inner one; if its slot were reused, there would be a COMPOUND_EXPR around the TARGET_EXPR. For 107329, if we're setting *walk_subtrees, we also need to fold TARGET_EXPR_CLEANUP. PR c++/107303 PR c++/107329 gcc/cp/ChangeLog: * cp-gimplify.cc (cp_fold_r) [TARGET_EXPR]: In case of double TARGET_EXPR, keep the outer one instead of the inner one. (maybe_replace_decl): New. gcc/testsuite/ChangeLog: * g++.dg/ext/builtin-shufflevector-5.C: New test. * g++.dg/init/new51.C: New test. Diff: --- gcc/cp/cp-gimplify.cc | 31 +++++++++++++++++++--- gcc/testsuite/g++.dg/ext/builtin-shufflevector-5.C | 14 ++++++++++ gcc/testsuite/g++.dg/init/new51.C | 10 +++++++ 3 files changed, 52 insertions(+), 3 deletions(-) diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc index 83ba1285bfd..92cd309e670 100644 --- a/gcc/cp/cp-gimplify.cc +++ b/gcc/cp/cp-gimplify.cc @@ -952,6 +952,28 @@ cp_genericize_target_expr (tree *stmt_p) gcc_assert (!DECL_INITIAL (slot)); } +/* Similar to if (target_expr_needs_replace) replace_decl, but TP is the + TARGET_EXPR_INITIAL, and this also updates *_SLOT. We need this extra + replacement when cp_folding TARGET_EXPR to preserve the invariant that + AGGR_INIT_EXPR_SLOT agrees with the enclosing TARGET_EXPR_SLOT. */ + +bool +maybe_replace_decl (tree *tp, tree decl, tree replacement) +{ + if (!*tp || !VOID_TYPE_P (TREE_TYPE (*tp))) + return false; + tree t = *tp; + while (TREE_CODE (t) == COMPOUND_EXPR) + t = TREE_OPERAND (t, 1); + if (TREE_CODE (t) == AGGR_INIT_EXPR) + replace_decl (&AGGR_INIT_EXPR_SLOT (t), decl, replacement); + else if (TREE_CODE (t) == VEC_INIT_EXPR) + replace_decl (&VEC_INIT_EXPR_SLOT (t), decl, replacement); + else + replace_decl (tp, decl, replacement); + return true; +} + /* Genericization context. */ struct cp_genericize_data @@ -1116,15 +1138,18 @@ cp_fold_r (tree *stmt_p, int *walk_subtrees, void *data_) cp_genericize_target_expr (stmt_p); /* Folding might replace e.g. a COND_EXPR with a TARGET_EXPR; in - that case, use it in place of this one. */ + that case, strip it in favor of this one. */ if (tree &init = TARGET_EXPR_INITIAL (stmt)) { cp_walk_tree (&init, cp_fold_r, data, NULL); + cp_walk_tree (&TARGET_EXPR_CLEANUP (stmt), cp_fold_r, data, NULL); *walk_subtrees = 0; if (TREE_CODE (init) == TARGET_EXPR) { - TARGET_EXPR_ELIDING_P (init) = TARGET_EXPR_ELIDING_P (stmt); - *stmt_p = init; + tree sub = TARGET_EXPR_INITIAL (init); + maybe_replace_decl (&sub, TARGET_EXPR_SLOT (init), + TARGET_EXPR_SLOT (stmt)); + init = sub; } } break; diff --git a/gcc/testsuite/g++.dg/ext/builtin-shufflevector-5.C b/gcc/testsuite/g++.dg/ext/builtin-shufflevector-5.C new file mode 100644 index 00000000000..06472b8d86b --- /dev/null +++ b/gcc/testsuite/g++.dg/ext/builtin-shufflevector-5.C @@ -0,0 +1,14 @@ +// PR c++/107303 +// { dg-options "-Wno-psabi" } + +typedef __attribute__((__vector_size__ (2))) unsigned short U; +typedef __attribute__((__vector_size__ (8))) unsigned short V; + +U u0, u1, u2; +V v; + +void +foo (void) +{ + u0 *= +__builtin_shufflevector (__builtin_shufflevector (u1, v, 3, 1), u2, 0); +} diff --git a/gcc/testsuite/g++.dg/init/new51.C b/gcc/testsuite/g++.dg/init/new51.C new file mode 100644 index 00000000000..d8b336476d9 --- /dev/null +++ b/gcc/testsuite/g++.dg/init/new51.C @@ -0,0 +1,10 @@ +// PR c++/107329 + +struct RexxClass { + void *operator new(unsigned long, unsigned long, const char *, RexxClass *, + RexxClass *); + void operator delete(void *, unsigned long, const char *, RexxClass *, + RexxClass *); + RexxClass(); +}; +void createInstance() { new (sizeof(RexxClass), "", 0, 0) RexxClass; }
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