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| author | Jeffrey A Law <law@cygnus.com> | 1998-10-19 12:20:32 +0000 |
|---|---|---|
| committer | Jeff Law <law@gcc.gnu.org> | 1998-10-19 06:20:32 -0600 |
| commit | e1f7435e415108d10eb601d21b5785bbbc838e54 (patch) | |
| tree | b1a9832b2f3894b411416df36de55cfcff6ee8e0 | |
| parent | 38bf4c6fcdb82bd51a0293d6c64695499083aefb (diff) | |
| download | gcc-e1f7435e415108d10eb601d21b5785bbbc838e54.zip gcc-e1f7435e415108d10eb601d21b5785bbbc838e54.tar.gz gcc-e1f7435e415108d10eb601d21b5785bbbc838e54.tar.bz2 | |
loop.c (scan_loop): Be more selective about what invariants are moved out of a loop.
* loop.c (scan_loop): Be more selective about what invariants are
moved out of a loop.
From-SVN: r23178
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/loop.c | 21 |
2 files changed, 11 insertions, 15 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 6acdbae..5d3a4cb 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +Mon Oct 19 11:40:56 1998 Jeffrey A Law (law@cygnus.com) + + * loop.c (scan_loop): Be more selective about what invariants are + moved out of a loop. + Mon Oct 19 10:46:58 PDT 1998 Jeff Law (law@cygnus.com) * version.c: Bump for snapshot. @@ -837,13 +837,7 @@ scan_loop (loop_start, end, unroll_p, bct_p) We don't know its life-span, so we can't compute the benefit. */ if (REGNO (SET_DEST (set)) >= max_reg_before_loop) ; - else if (/* The set is a user-variable or it is used in - the exit test (this can cause the variable to be - used before it is set just like a - user-variable)... */ - (REG_USERVAR_P (SET_DEST (set)) - || REG_LOOP_TEST_P (SET_DEST (set))) - /* And the set is not guaranteed to be executed one + else if (/* The set is not guaranteed to be executed one the loop starts, or the value before the set is needed before the set occurs... */ && (maybe_never @@ -854,14 +848,11 @@ scan_loop (loop_start, end, unroll_p, bct_p) something after this point in the loop might depend on its value before the set). */ && !reg_in_basic_block_p (p, SET_DEST (set))) - /* It is unsafe to move the set. The fact that these - three conditions are considered in conjunction means - that we are assuming various conditions, such as: - - o It's OK to move a set of a variable which was not - created by the user and is not used in an exit test - even if that point in the set would not be reached - during execution of the loop. */ + /* It is unsafe to move the set. + + This code used to consider it OK to move a set of a variable + which was not created by the user and not used in an exit test. + That behavior is incorrect and was removed. */ ; else if ((tem = invariant_p (src)) && (dependencies == 0 |