[PATCH] rtl-optimization/98144 - tame REE memory usage
Richard Biener
rguenther@suse.de
Fri Jan 29 09:51:59 GMT 2021
This changes the REE dataflow to change the explicit all-ones
starting solution to be implicit via a visited flag, removing
the need to initially start with fully populated bitmaps for
all basic-blocks. That reduces peak memory use when compiling
the RTL checking enabled insn-extract.c testcase from PR98144
from 6GB to less than 2GB.
Bootstrapped and tested on x86_64-unknown-linux-gnu.
OK for trunk and branches?
Thanks,
Richard.
2021-01-29 Richard Biener <rguenther@suse.de>
PR rtl-optimization/98144
* df.h (df_mir_bb_info): Add con_visited member.
* df-problems.c (df_mir_alloc): Initialize con_visited,
do not fully populate IN and OUT.
(df_mir_reset): Likewise.
(df_mir_confluence_0): Set con_visited.
(df_mir_confluence_n): Properly handle implicitely
fully populated IN and OUT as designated by con_visited
and update con_visited accordingly.
---
gcc/df-problems.c | 28 +++++++++++++++++++++-------
gcc/df.h | 1 +
2 files changed, 22 insertions(+), 7 deletions(-)
diff --git a/gcc/df-problems.c b/gcc/df-problems.c
index 53a1f0d9dd6..8fe58581f32 100644
--- a/gcc/df-problems.c
+++ b/gcc/df-problems.c
@@ -1917,8 +1917,7 @@ df_mir_alloc (bitmap all_blocks)
bitmap_initialize (&bb_info->gen, &problem_data->mir_bitmaps);
bitmap_initialize (&bb_info->in, &problem_data->mir_bitmaps);
bitmap_initialize (&bb_info->out, &problem_data->mir_bitmaps);
- bitmap_set_range (&bb_info->in, 0, DF_REG_SIZE (df));
- bitmap_set_range (&bb_info->out, 0, DF_REG_SIZE (df));
+ bb_info->con_visited = false;
}
}
@@ -1941,9 +1940,8 @@ df_mir_reset (bitmap all_blocks)
gcc_assert (bb_info);
bitmap_clear (&bb_info->in);
- bitmap_set_range (&bb_info->in, 0, DF_REG_SIZE (df));
bitmap_clear (&bb_info->out);
- bitmap_set_range (&bb_info->out, 0, DF_REG_SIZE (df));
+ bb_info->con_visited = false;
}
}
@@ -2021,6 +2019,7 @@ df_mir_confluence_0 (basic_block bb)
class df_mir_bb_info *bb_info = df_mir_get_bb_info (bb->index);
bitmap_clear (&bb_info->in);
+ bb_info->con_visited = true;
}
@@ -2029,12 +2028,27 @@ df_mir_confluence_0 (basic_block bb)
static bool
df_mir_confluence_n (edge e)
{
- bitmap op1 = &df_mir_get_bb_info (e->dest->index)->in;
- bitmap op2 = &df_mir_get_bb_info (e->src->index)->out;
-
if (e->flags & EDGE_FAKE)
return false;
+ df_mir_bb_info *src_info = df_mir_get_bb_info (e->src->index);
+ /* If SRC was not visited yet then we'll and with all-ones which
+ means no changes. Do not consider DST con_visited by this
+ operation alone either. */
+ if (!src_info->con_visited)
+ return false;
+
+ df_mir_bb_info *dst_info = df_mir_get_bb_info (e->dest->index);
+ bitmap op1 = &dst_info->in;
+ bitmap op2 = &src_info->out;
+ /* If DEST was not visited yet just copy the SRC bitmap. */
+ if (!dst_info->con_visited)
+ {
+ dst_info->con_visited = true;
+ bitmap_copy (op1, op2);
+ return true;
+ }
+
/* A register is must-initialized at the entry of a basic block iff it is
must-initialized at the exit of all the predecessors. */
return bitmap_and_into (op1, op2);
diff --git a/gcc/df.h b/gcc/df.h
index 88d35e49afd..5effefaa6e3 100644
--- a/gcc/df.h
+++ b/gcc/df.h
@@ -929,6 +929,7 @@ public:
/* The results of the dataflow problem. */
bitmap_head in; /* At the top of the block. */
bitmap_head out; /* At the bottom of the block. */
+ bool con_visited; /* Visited by con_fun_{0,n}. */
};
--
2.26.2
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