[COMMITTED] Allow ranger queries on exit block.
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Commit Message
Ranger was not allowing the exit block to be queried for range_on_entry
or exit, for no good reason. This removes that restriction.
Interestingly, it seems that when we calculate dominance info, GCC does
not set the dominators for the EXIT_BLOCK? I worked around it by
starting with a single pred of the exit block for my queries, but as a
result it doesn't support multiple exit blocks.
For the record:
get_immediate_dominator (CDI_DOMINATORS, EXIT_BLOCK_PTR_FOR_FN (cfun))
returns NULL. Is this actually working as intended? It was unexpected
on my part.
Bootstrapped on x86_64-pc-linux-gnu with no regressions. Pushed.
Andrew
Comments
On Tue, Nov 1, 2022 at 2:20 PM Andrew MacLeod via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Ranger was not allowing the exit block to be queried for range_on_entry
> or exit, for no good reason. This removes that restriction.
>
> Interestingly, it seems that when we calculate dominance info, GCC does
> not set the dominators for the EXIT_BLOCK? I worked around it by
> starting with a single pred of the exit block for my queries, but as a
> result it doesn't support multiple exit blocks.
>
> For the record:
>
> get_immediate_dominator (CDI_DOMINATORS, EXIT_BLOCK_PTR_FOR_FN (cfun))
>
> returns NULL. Is this actually working as intended? It was unexpected
> on my part.
Yes, working as "intended". EXIT and ENTRY
basic-blocks are artificial so having dominance info for them would be
somewhat odd.
Richard.
>
> Bootstrapped on x86_64-pc-linux-gnu with no regressions. Pushed.
>
> Andrew
From 592bbe3d7eb3cff656c731e84ad872719a4a9d16 Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacleod@redhat.com>
Date: Mon, 31 Oct 2022 10:56:25 -0400
Subject: [PATCH 2/3] Allow queries on exit block.
Ranger was not allowing the exit block to be queried for range_on_entry
or exit. This removes that restriction.
* gimple-range-cache.cc (ranger_cache::fill_block_cache): Allow
exit block to be specified.
(ranger_cache::range_from_dom): If exit block is specified, use
the immediate predecessor instead of the dominator to start.
* gimple-range.cc (gimple_ranger::range_on_exit): Allow query
for exit block.
---
gcc/gimple-range-cache.cc | 16 ++++++++++------
gcc/gimple-range.cc | 1 -
2 files changed, 10 insertions(+), 7 deletions(-)
@@ -1193,9 +1193,8 @@ ranger_cache::fill_block_cache (tree name, basic_block bb, basic_block def_bb)
Value_Range block_result (type);
Value_Range undefined (type);
- // At this point we shouldn't be looking at the def, entry or exit block.
- gcc_checking_assert (bb != def_bb && bb != ENTRY_BLOCK_PTR_FOR_FN (cfun) &&
- bb != EXIT_BLOCK_PTR_FOR_FN (cfun));
+ // At this point we shouldn't be looking at the def, entry block.
+ gcc_checking_assert (bb != def_bb && bb != ENTRY_BLOCK_PTR_FOR_FN (cfun));
gcc_checking_assert (m_workback.length () == 0);
// If the block cache is set, then we've already visited this block.
@@ -1434,10 +1433,15 @@ ranger_cache::range_from_dom (vrange &r, tree name, basic_block start_bb,
// Default value is global range.
get_global_range (r, name);
+ // The dominator of EXIT_BLOCK doesn't seem to be set, so at least handle
+ // the common single exit cases.
+ if (start_bb == EXIT_BLOCK_PTR_FOR_FN (cfun) && single_pred_p (start_bb))
+ bb = single_pred_edge (start_bb)->src;
+ else
+ bb = get_immediate_dominator (CDI_DOMINATORS, start_bb);
+
// Search until a value is found, pushing blocks which may need calculating.
- for (bb = get_immediate_dominator (CDI_DOMINATORS, start_bb);
- bb;
- prev_bb = bb, bb = get_immediate_dominator (CDI_DOMINATORS, bb))
+ for ( ; bb; prev_bb = bb, bb = get_immediate_dominator (CDI_DOMINATORS, bb))
{
// Accumulate any block exit inferred ranges.
m_exit.maybe_adjust_range (infer, name, bb);
@@ -167,7 +167,6 @@ void
gimple_ranger::range_on_exit (vrange &r, basic_block bb, tree name)
{
// on-exit from the exit block?
- gcc_checking_assert (bb != EXIT_BLOCK_PTR_FOR_FN (cfun));
gcc_checking_assert (gimple_range_ssa_p (name));
unsigned idx;
--
2.37.3