diff options
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/alias.c | 7 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/opt/alias1.C | 25 |
3 files changed, 37 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 7c66b67..760dd95 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2001-08-07 Jason Merrill <jason_merrill@redhat.com> + + * alias.c (get_alias_set): Return a previously calculated + alias set for a VAR_DECL. + 2001-08-06 Richard Henderson <rth@redhat.com> * varasm.c (assemble_gc_entry): Remove. diff --git a/gcc/alias.c b/gcc/alias.c index e741718..a529a01 100644 --- a/gcc/alias.c +++ b/gcc/alias.c @@ -527,6 +527,13 @@ get_alias_set (t) return 0; } + /* If we've already determined the alias set for this decl, just + return it. This is necessary for C++ anonymous unions, whose + component variables don't look like union members (boo!). */ + if (TREE_CODE (t) == VAR_DECL + && DECL_RTL_SET_P (t) && GET_CODE (DECL_RTL (t)) == MEM) + return MEM_ALIAS_SET (DECL_RTL (t)); + /* Give the language another chance to do something special. */ if (orig_t != t && (set = lang_get_alias_set (t)) != -1) diff --git a/gcc/testsuite/g++.dg/opt/alias1.C b/gcc/testsuite/g++.dg/opt/alias1.C new file mode 100644 index 0000000..34aed59 --- /dev/null +++ b/gcc/testsuite/g++.dg/opt/alias1.C @@ -0,0 +1,25 @@ +// Test that type punning using an anonymous union works with strict aliasing. +// { dg-do run } +// { dg-options -O2 -fstrict-aliasing } + +extern "C" void abort (); + +void f (int i) +{ + union + { + int ui; + float uf[2]; + }; + + ui = i; + if (uf[0] != 42.0) + abort (); +} + +int main () +{ + union U { int i; float f[2]; } u; + u.f[0] = 42.0; + f (u.i); +} |