On 1/26/22 04:33, Jakub Jelinek wrote:
Hi!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.
OK.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? 2022-01-26 Jakub Jelinek <ja...@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. --- gcc/cp/constexpr.cc.jj 2022-01-19 00:42:11.000000000 +0100 +++ gcc/cp/constexpr.cc 2022-01-25 21:44:28.459208756 +0100 @@ -4658,6 +4658,13 @@ init_subob_ctx (const constexpr_ctx *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 --- gcc/testsuite/g++.dg/cpp0x/constexpr-104226.C.jj 2022-01-25 21:50:34.977031244 +0100 +++ gcc/testsuite/g++.dg/cpp0x/constexpr-104226.C 2022-01-25 21:51:41.851086559 +0100 @@ -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); +} Jakub
