From 15237f9a89b2d626073e1261e19b6608088e1d70 Mon Sep 17 00:00:00 2001 From: Jason Merrill Date: Mon, 13 Apr 2009 16:53:34 -0400 Subject: [PATCH] re PR c++/39480 (generated memcpy causes trouble in assignment) PR c++/39480 * call.c (build_over_call): Don't call memcpy if the target is the same as the source. From-SVN: r146011 --- gcc/cp/ChangeLog | 6 ++++++ gcc/cp/call.c | 14 ++++++++++++++ gcc/testsuite/ChangeLog | 5 +++++ gcc/testsuite/g++.dg/init/copy7.C | 32 +++++++++++++++++++++++++++++++ 4 files changed, 57 insertions(+) create mode 100644 gcc/testsuite/g++.dg/init/copy7.C diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 905b6e431dd..d77634d3263 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,9 @@ +2009-04-09 Jason Merrill + + PR c++/39480 + * call.c (build_over_call): Don't call memcpy if the target is + the same as the source. + 2009-04-13 Jason Merrill PR c++/39750 diff --git a/gcc/cp/call.c b/gcc/cp/call.c index 869146efe8e..ef7c045acab 100644 --- a/gcc/cp/call.c +++ b/gcc/cp/call.c @@ -5396,14 +5396,28 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain) instead of an explicit call to memcpy. */ tree arg0, arg1, arg2, t; + tree test = NULL_TREE; arg2 = TYPE_SIZE_UNIT (as_base); arg1 = arg; arg0 = cp_build_unary_op (ADDR_EXPR, to, 0, complain); + + if (!(optimize && flag_tree_ter)) + { + /* When TER is off get_pointer_alignment returns 0, so a call + to __builtin_memcpy is expanded as a call to memcpy, which + is invalid with identical args. When TER is on it is + expanded as a block move, which should be safe. */ + arg0 = save_expr (arg0); + arg1 = save_expr (arg1); + test = build2 (EQ_EXPR, boolean_type_node, arg0, arg1); + } t = implicit_built_in_decls[BUILT_IN_MEMCPY]; t = build_call_n (t, 3, arg0, arg1, arg2); t = convert (TREE_TYPE (arg0), t); + if (test) + t = build3 (COND_EXPR, TREE_TYPE (t), test, arg0, t); val = cp_build_indirect_ref (t, 0, complain); } diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index d29496fb18b..457aee66bb2 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2009-04-09 Jason Merrill + + PR c++/39480 + * g++.dg/init/copy7.C: New. + 2009-04-13 H.J. Lu PR testsuite/39733 diff --git a/gcc/testsuite/g++.dg/init/copy7.C b/gcc/testsuite/g++.dg/init/copy7.C new file mode 100644 index 00000000000..f4364f329e5 --- /dev/null +++ b/gcc/testsuite/g++.dg/init/copy7.C @@ -0,0 +1,32 @@ +// PR c++/39480 +// It isn't always safe to call memcpy with identical arguments. +// { dg-do run } + +extern "C" void abort(); +extern "C" void * +memcpy(void *dest, void *src, __SIZE_TYPE__ n) +{ + abort(); +} + +struct A +{ + double d[10]; +}; + +struct B: public A +{ + char bc; +}; + +B b; + +void f(B *a1, B* a2) +{ + *a1 = *a2; +} + +int main() +{ + f(&b,&b); +} -- 2.30.2