* [PATCH] tweak range-on-exit.
@ 2021-05-07 19:03 Andrew MacLeod
2021-05-08 15:05 ` Aldy Hernandez
0 siblings, 1 reply; 2+ messages in thread
From: Andrew MacLeod @ 2021-05-07 19:03 UTC (permalink / raw)
To: gcc-patches
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Range on exit was not ding the right thing when a basic block contained
no statements other than a PHI node.
Rather than returning the value of the PHI, it was instead asking for
range-on-entry for the phi, which would trigger a walk back to the top
of the CFG looking for the definition. When it didnt find it, it would
then default to the global-value calculation. So it ended up with the
right value, but it does a lot of unnecessary work and put entries in
the on-entry cache that don't need to be there.
Bootstraps on x86_64-pc-linux-gnu with no testsuite regressions.
Pushed.
Andrew
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commit c0c25d1052950cecbf4488b7f76d41952672414a
Author: Andrew MacLeod <amacleod@redhat.com>
Date: Mon Apr 26 19:23:25 2021 -0400
Fix range_on_exit for PHI stmts when there are no other stmts in the block.
last_stmt(bb) returns NULL for blocks which only have PHI stmts, and
range_on_exit would trigger a cache fill all the way to the top of the
program for the SSA_NAME.
* gimple-range.cc (gimple_ranger::range_on_exit): Handle block with
only PHI nodes better.
diff --git a/gcc/gimple-range.cc b/gcc/gimple-range.cc
index 6158a754dd6..e94bb355de3 100644
--- a/gcc/gimple-range.cc
+++ b/gcc/gimple-range.cc
@@ -1003,14 +1003,23 @@ gimple_ranger::range_on_exit (irange &r, basic_block bb, tree name)
gcc_checking_assert (bb != EXIT_BLOCK_PTR_FOR_FN (cfun));
gcc_checking_assert (gimple_range_ssa_p (name));
- gimple *s = last_stmt (bb);
- // If there is no statement in the block and this isn't the entry
- // block, go get the range_on_entry for this block. For the entry
- // block, a NULL stmt will return the global value for NAME.
- if (!s && bb != ENTRY_BLOCK_PTR_FOR_FN (cfun))
- range_on_entry (r, bb, name);
- else
+ gimple *s = SSA_NAME_DEF_STMT (name);
+ basic_block def_bb = gimple_bb (s);
+ // If this is not the definition block, get the range on the last stmt in
+ // the block... if there is one.
+ if (def_bb != bb)
+ s = last_stmt (bb);
+ // If there is no statement provided, get the range_on_entry for this block.
+ if (s)
range_of_expr (r, name, s);
+ else
+ {
+ range_on_entry (r, bb, name);
+ // See if there was a deref in this block, if applicable
+ if (!cfun->can_throw_non_call_exceptions && r.varying_p () &&
+ m_cache.m_non_null.non_null_deref_p (name, bb))
+ r = range_nonzero (TREE_TYPE (name));
+ }
gcc_checking_assert (r.undefined_p ()
|| range_compatible_p (r.type (), TREE_TYPE (name)));
}
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] tweak range-on-exit.
2021-05-07 19:03 [PATCH] tweak range-on-exit Andrew MacLeod
@ 2021-05-08 15:05 ` Aldy Hernandez
0 siblings, 0 replies; 2+ messages in thread
From: Aldy Hernandez @ 2021-05-08 15:05 UTC (permalink / raw)
To: Andrew MacLeod, gcc-patches
On 5/7/21 9:03 PM, Andrew MacLeod wrote:
> + else
> + {
> + range_on_entry (r, bb, name);
> + // See if there was a deref in this block, if applicable
> + if (!cfun->can_throw_non_call_exceptions && r.varying_p () &&
> + m_cache.m_non_null.non_null_deref_p (name, bb))
> + r = range_nonzero (TREE_TYPE (name));
> + }
Nit. The final && must go on the following line. And it probably looks
better if you put each "&& conditional" on its own line.
Aldy
^ permalink raw reply [flat|nested] 2+ messages in thread
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