diff options
| author | Richard Kenner <kenner@vlsi1.ultra.nyu.edu> | 2000-09-17 15:33:30 +0000 |
|---|---|---|
| committer | Richard Kenner <kenner@gcc.gnu.org> | 2000-09-17 11:33:30 -0400 |
| commit | ec56965643d368ba8eae4ce34af4439aa9dd7b31 (patch) | |
| tree | a088015564b8aca06f881097758706390ad3463f /gcc/alias.c | |
| parent | 23cb1766e03f75f32a723f63c7c68287d6822fff (diff) | |
| download | gcc-ec56965643d368ba8eae4ce34af4439aa9dd7b31.zip gcc-ec56965643d368ba8eae4ce34af4439aa9dd7b31.tar.gz gcc-ec56965643d368ba8eae4ce34af4439aa9dd7b31.tar.bz2 | |
alias.c (true_dependence): Allow non-unchanging read to conflict with unchanging write.
* alias.c (true_dependence): Allow non-unchanging read to conflict
with unchanging write.
From-SVN: r36476
Diffstat (limited to 'gcc/alias.c')
| -rw-r--r-- | gcc/alias.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/gcc/alias.c b/gcc/alias.c index be46281..65b053f 100644 --- a/gcc/alias.c +++ b/gcc/alias.c @@ -1600,10 +1600,13 @@ true_dependence (mem, mem_mode, x, varies) A non-unchanging read can conflict with a non-unchanging write. An unchanging read can conflict with an unchanging write since there may be a single store to this address to initialize it. + Note that an unchanging store can conflict with a non-unchanging read + since we have to make conservative assumptions when we have a + record with readonly fields and we are copying the whole thing. Just fall through to the code below to resolve potential conflicts. This won't handle all cases optimally, but the possible performance loss should be negligible. */ - if (RTX_UNCHANGING_P (x) != RTX_UNCHANGING_P (mem)) + if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem)) return 0; if (mem_mode == VOIDmode) |