On Thu, Mar 15, 2018 at 4:50 AM, Richard Biener <richard.guent...@gmail.com> wrote: > On Wed, Mar 14, 2018 at 8:57 PM, Jason Merrill <ja...@redhat.com> wrote: >> Ping >> >> On Fri, Mar 2, 2018 at 1:23 PM, Jason Merrill <ja...@redhat.com> wrote: >>> As I mentioned in the PR, the problem here is that we're replacing a >>> constructor with a dispatcher function which doesn't look much like a >>> constructor. This patch adjusts make_dispatcher_decl to make it look >>> more like the functions it dispatches to, but other things are certain >>> to break for similar reasons down the road. A proper solution should >>> be more transparent, like thunks. >>> >>> Tested x86_64-pc-linux-gnu. Does this seem worth applying to fix the >>> regression? > > The patch looks reasonable to me, you probably know best whether > the cp/ parts are risky or not ;) > > So - OK from my POV. > > And yes, thunks may be a better representation for the dispatcher.
It occurred to me that I could handle this more locally by deferring the function substitution until genericization time, so this is what I'm checking in:
commit 05dda93e56e02859c65f93bd541dc7793bc7305c Author: Jason Merrill <ja...@redhat.com> Date: Fri Feb 16 16:53:47 2018 -0500 PR c++/83911 - ICE with multiversioned constructor. * cp-gimplify.c (cp_genericize_r): Replace versioned function with dispatchere here. * call.c (build_over_call): Not here. PR c++/83911 - ICE with multiversioned constructor. diff --git a/gcc/cp/call.c b/gcc/cp/call.c index 45c22aaa312..67438ff2e94 100644 --- a/gcc/cp/call.c +++ b/gcc/cp/call.c @@ -8204,23 +8204,6 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain) } } - /* For calls to a multi-versioned function, overload resolution - returns the function with the highest target priority, that is, - the version that will checked for dispatching first. If this - version is inlinable, a direct call to this version can be made - otherwise the call should go through the dispatcher. */ - - if (DECL_FUNCTION_VERSIONED (fn) - && (current_function_decl == NULL - || !targetm.target_option.can_inline_p (current_function_decl, fn))) - { - fn = get_function_version_dispatcher (fn); - if (fn == NULL) - return NULL; - if (!already_used) - mark_versions_used (fn); - } - if (!already_used && !mark_used (fn, complain)) return error_mark_node; diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c index 0ddd435454c..653d1dcee26 100644 --- a/gcc/cp/cp-gimplify.c +++ b/gcc/cp/cp-gimplify.c @@ -1513,6 +1513,29 @@ cp_genericize_r (tree *stmt_p, int *walk_subtrees, void *data) == REFERENCE_TYPE)) *walk_subtrees = 0; } + /* Fall through. */ + case AGGR_INIT_EXPR: + /* For calls to a multi-versioned function, overload resolution + returns the function with the highest target priority, that is, + the version that will checked for dispatching first. If this + version is inlinable, a direct call to this version can be made + otherwise the call should go through the dispatcher. */ + { + tree fn = cp_get_callee_fndecl (stmt); + if (fn && DECL_FUNCTION_VERSIONED (fn) + && (current_function_decl == NULL + || !targetm.target_option.can_inline_p (current_function_decl, + fn))) + if (tree dis = get_function_version_dispatcher (fn)) + { + mark_versions_used (dis); + dis = build_address (dis); + if (TREE_CODE (stmt) == CALL_EXPR) + CALL_EXPR_FN (stmt) = dis; + else + AGGR_INIT_EXPR_FN (stmt) = dis; + } + } break; default: diff --git a/gcc/testsuite/g++.dg/ext/mv27.C b/gcc/testsuite/g++.dg/ext/mv27.C new file mode 100644 index 00000000000..443a54be765 --- /dev/null +++ b/gcc/testsuite/g++.dg/ext/mv27.C @@ -0,0 +1,18 @@ +// PR c++/83911 +// { dg-do compile { target i?86-*-* x86_64-*-* } } +// { dg-require-ifunc "" } + +class SimdFloat +{ +public: + __attribute__ ((target ("default"))) + SimdFloat(float x) {} + + __attribute__ ((target ("avx2"))) + SimdFloat(float x) {} +}; + +SimdFloat foo() +{ + return 1; +}