| Message ID | 20110127201329.GP2724@tyan-ft48-01.lab.bos.redhat.com |
|---|---|
| State | New |
| Headers | show |
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 01/27/11 13:13, Jakub Jelinek wrote: > On Thu, Jan 27, 2011 at 09:48:00AM +0100, Jakub Jelinek wrote: >> On Wed, Jan 26, 2011 at 06:29:25PM -0700, Jeff Law wrote: >>> Well, one could easily argue that using the original expression in the >>> REG_EQUAL note is incorrect as well. In fact, looking over all the >>> calls to set_unique_reg_note shows that most either copy the value or >>> generate a new one. >>> >>> I think that means we actually want both the varasm.c and the expr.c >>> change to avoid incorrect sharing. >> >> I think the reason why most of the set_unique_reg_note calls copy_rtx >> is that the pattern is usually kept in the insn (or in some other insn). >> In the emit_move_insn case it specifically tests that the pattern is not >> there (well, some weird target could embed it in some unspec or something), >> the reason I changed force_const_mem was to deal with any other uses of >> force_const_mem. >> >> But I guess if you strongly prefer to have it in both places I can test a >> patch. > > This passed bootstrap/regtest on x86_64-linux and i686-linux too: > > 2011-01-27 Jakub Jelinek <jakub@redhat.com> > > PR target/42894 > * varasm.c (force_const_mem): Store copy of x in desc->constant > instead of x itself. > * expr.c (emit_move_insn): Add a copy of y_cst instead of y_cst > itself into REG_EQUAL note. > > * gcc.dg/tls/pr42894.c: New test. Let's go with this. It should be the safest -- and if a port shows up which assumes the pool entries are shared, we can certainly deal with it. Jeff -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJNQwc0AAoJEBRtltQi2kC7huIIAK/H18lSp/ZQj4xgtjqCsk8j H2BUqVRzI1hWiVI3BkmUl6PW3Xl0Qa/cfbtIEljELgfZ/yxxKwmDrlFJfP1yCEJX 1CP1wO5ox73wN68+8Axhy6479C6cIurWCMs18oBNOGi0LLmUPYZgDgKjrzSX1r7w VGtcv+V3UzRz56lQqDKblui55ZqeDMKXXq7pHhDw+qNebKncpQtZAZPeZhYKh/Ey YKoIxQCqpVjEDapSRhOUkRwmxw9Y748EMooR2Zh8JiLzqx28wfbc2ZzfS/yT/vIG yInJ5RKyMdfXtmXT3I/gjkxKDM+zpdQvMRj588tudUlHmTWBImXU34OqDl1QkHk= =R1q2 -----END PGP SIGNATURE-----
--- gcc/varasm.c.jj 2011-01-25 12:58:41.000000000 +0100 +++ gcc/varasm.c 2011-01-26 14:07:50.635389932 +0100 @@ -3518,7 +3518,7 @@ force_const_mem (enum machine_mode mode, pool->offset &= ~ ((align / BITS_PER_UNIT) - 1); desc->next = NULL; - desc->constant = tmp.constant; + desc->constant = copy_rtx (tmp.constant); desc->offset = pool->offset; desc->hash = hash; desc->mode = mode; --- gcc/expr.c.jj 2011-01-26 14:07:50.635389932 +0100 +++ gcc/expr.c 2011-01-27 17:05:04.936795133 +0100 @@ -3398,7 +3398,7 @@ emit_move_insn (rtx x, rtx y) && (set = single_set (last_insn)) != NULL_RTX && SET_DEST (set) == x && ! rtx_equal_p (y_cst, SET_SRC (set))) - set_unique_reg_note (last_insn, REG_EQUAL, y_cst); + set_unique_reg_note (last_insn, REG_EQUAL, copy_rtx (y_cst)); return last_insn; } --- gcc/testsuite/gcc.dg/tls/pr42894.c.jj 2011-01-26 16:29:13.765389223 +0100 +++ gcc/testsuite/gcc.dg/tls/pr42894.c 2011-01-26 16:31:46.830433380 +0100 @@ -0,0 +1,12 @@ +/* PR target/42894 */ +/* { dg-do compile } */ +/* { dg-options "-march=armv5te -mthumb" { target arm*-*-* } } */ +/* { dg-require-effective-target tls } */ + +extern __thread int t; + +void +foo (int a) +{ + t = a; +}