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.
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
