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From: Jakub Jelinek <jakub@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-6881] c++: Fix up handling of vector CONSTRUCTORs with vectors in it in constexpr.cc [PR104226] Date: Wed, 26 Jan 2022 18:41:48 +0000 (GMT) [thread overview] Message-ID: <20220126184148.58926382C400@sourceware.org> (raw) https://gcc.gnu.org/g:abea1c9a252ef7712ab800360e1e0e2697ee14f2 commit r12-6881-gabea1c9a252ef7712ab800360e1e0e2697ee14f2 Author: Jakub Jelinek <jakub@redhat.com> Date: Wed Jan 26 19:40:29 2022 +0100 c++: Fix up handling of vector CONSTRUCTORs with vectors in it in constexpr.cc [PR104226] The middle-end uses sometimes VECTOR_TYPE CONSTRUCTORs that contain some other VECTOR_TYPE elements in it (should be with compatible element size and smaller number of elements, e.g. a V8SImode vector can be constructed as { V4SImode_var_1, V4SImode_var_2 }), and expansion of __builtin_shufflevector emits these early, so constexpr.cc can see those too. constexpr.cc already has special cases for NULL index which is typical for VECTOR_TYPE CONSTRUCTORs, and for VECTOR_TYPE CONSTRUCTORs that contain just scalar elts that works just fine - init_subob_ctx just returns on non-aggregate elts and get_or_insert_ctor_field has if (TREE_CODE (type) == VECTOR_TYPE && index == NULL_TREE) { CONSTRUCTOR_APPEND_ELT (CONSTRUCTOR_ELTS (ctor), index, NULL_TREE); return &CONSTRUCTOR_ELTS (ctor)->last(); } handling for it. But for the vector in vector case init_subob_ctx would try to create a sub-CONSTRUCTOR and even didn't handle the NULL index case well, so instead of creating the sub-CONSTRUCTOR after the elts already in it overwrote the first one. So (V8SImode) { { 0, 0, 0, 0 }, { 0, 0, 0, 0 } } became (V8SImode) { 0, 0, 0, 0 } The following patch fixes it by not forcing a sub-CONSTRUCTOR for this vector in vector case. 2022-01-26 Jakub Jelinek <jakub@redhat.com> PR c++/104226 * constexpr.cc (init_subob_ctx): For vector ctors containing vector elements, ensure appending to the same ctor instead of creating another one. * g++.dg/cpp0x/constexpr-104226.C: New test. Diff: --- gcc/cp/constexpr.cc | 7 +++++++ gcc/testsuite/g++.dg/cpp0x/constexpr-104226.C | 15 +++++++++++++++ 2 files changed, 22 insertions(+) diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc index dcc167499ed..7f4425326be 100644 --- a/gcc/cp/constexpr.cc +++ b/gcc/cp/constexpr.cc @@ -4658,6 +4658,13 @@ init_subob_ctx (const constexpr_ctx *ctx, constexpr_ctx &new_ctx, if (!AGGREGATE_TYPE_P (type) && !VECTOR_TYPE_P (type)) /* A non-aggregate member doesn't get its own CONSTRUCTOR. */ return; + if (VECTOR_TYPE_P (type) + && VECTOR_TYPE_P (TREE_TYPE (ctx->ctor)) + && index == NULL_TREE) + /* A vector inside of a vector CONSTRUCTOR, e.g. when a larger + vector is constructed from smaller vectors, doesn't get its own + CONSTRUCTOR either. */ + return; /* The sub-aggregate initializer might contain a placeholder; update object to refer to the subobject and ctor to refer to diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-104226.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-104226.C new file mode 100644 index 00000000000..a44f417f7ab --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-104226.C @@ -0,0 +1,15 @@ +// PR c++/104226 +// { dg-do compile } +// { dg-options "-Wno-psabi" } + +typedef unsigned short __attribute__((__vector_size__(16))) U; +typedef unsigned int __attribute__((__vector_size__(16))) V; +typedef unsigned int __attribute__((__vector_size__(32))) W; + +U +foo (void) +{ + return __builtin_convertvector (__builtin_shufflevector ((V){}, (W){}, + 0, 0, 1, 0, + 5, 5, 0, 2), U); +}
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