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LCM: Export 2 helpful functions as global for VSETVL PASS use in RISC-V backend

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This patch exports 'compute_antinout_edge' and 'compute_earliest' as global scope
which is going to be used in VSETVL PASS of RISC-V backend.

The demand fusion is the fusion of VSETVL information to emit VSETVL which dominate and pre-config for most
of the RVV instructions in order to elide redundant VSETVLs.

For exmaple:

for
 for
  for
    if (cond}
      VSETVL demand 1: SEW/LMUL = 16 and TU policy
    else
      VSETVL demand 2: SEW = 32

VSETVL pass should be able to fuse demand 1 and demand 2 into new demand: SEW = 32, LMUL = M2, TU policy.
Then emit such VSETVL at the outmost of the for loop to get the most optimal codegen and run-time execution.

Currenty the VSETVL PASS Phase 3 (demand fusion) is really messy and un-reliable as well as un-maintainable.
And, I recently read dragon book and morgan's book again, I found there "earliest" can allow us to do the
demand fusion in a very reliable and optimal way.

So, this patch exports these 2 functions which are very helpful for VSETVL pass.

gcc/ChangeLog:

	* lcm.cc (compute_antinout_edge): Export as global use.
	(compute_earliest): Ditto.
	(compute_rev_insert_delete): Ditto.
	* lcm.h (compute_antinout_edge): Ditto.
	(compute_earliest): Ditto.
This commit is contained in:
Juzhe-Zhong 2023-08-21 09:04:53 +08:00 • committed by Lehua Ding
parent 966b0a9652
commit d5dfba19ae
2 changed files with 5 additions and 5 deletions
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7
gcc/lcm.cc
View file

@ -56,9 +56,6 @@ along with GCC; see the file COPYING3. If not see
#include "lcm.h"
/* Edge based LCM routines. */
static void compute_antinout_edge (sbitmap *, sbitmap *, sbitmap *, sbitmap *);
static void compute_earliest (struct edge_list *, int, sbitmap *, sbitmap *,
sbitmap *, sbitmap *, sbitmap *);
static void compute_laterin (struct edge_list *, sbitmap *, sbitmap *,
sbitmap *, sbitmap *);
static void compute_insert_delete (struct edge_list *edge_list, sbitmap *,
@ -79,7 +76,7 @@ static void compute_rev_insert_delete (struct edge_list *edge_list, sbitmap *,
This is done based on the flow graph, and not on the pred-succ lists.
Other than that, its pretty much identical to compute_antinout. */
static void
void
compute_antinout_edge (sbitmap *antloc, sbitmap *transp, sbitmap *antin,
sbitmap *antout)
{
@ -170,7 +167,7 @@ compute_antinout_edge (sbitmap *antloc, sbitmap *transp, sbitmap *antin,
/* Compute the earliest vector for edge based lcm. */
static void
void
compute_earliest (struct edge_list *edge_list, int n_exprs, sbitmap *antin,
sbitmap *antout, sbitmap *avout, sbitmap *kill,
sbitmap *earliest)

3
gcc/lcm.h
View file

@ -31,4 +31,7 @@ extern struct edge_list *pre_edge_rev_lcm (int, sbitmap *,
sbitmap *, sbitmap *,
sbitmap *, sbitmap **,
sbitmap **);
extern void compute_antinout_edge (sbitmap *, sbitmap *, sbitmap *, sbitmap *);
extern void compute_earliest (struct edge_list *, int, sbitmap *, sbitmap *,
sbitmap *, sbitmap *, sbitmap *);
#endif /* GCC_LCM_H */