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[PR104637] LRA: Split hard regs as many as possible on one subpass 

LRA hard reg split subpass is a small subpass used as the last
resort for LRA when it can not assign a hard reg to a reload
pseudo by other ways (e.g. by spilling non-reload pseudos).  For
simplicity the subpass works on one split base (as each split
changes pseudo live range info).  In this case it results in
reaching maximal possible number of subpasses.  The patch
implements as many non-overlapping hard reg splits
splits as possible on each subpass.

gcc/ChangeLog:

	PR rtl-optimization/104637
	* lra-assigns.c (lra_split_hard_reg_for): Split hard regs as many
	as possible on one subpass.

gcc/testsuite/ChangeLog:

	PR rtl-optimization/104637
	* gcc.target/i386/pr104637.c: New.
This commit is contained in:
Vladimir N. Makarov 2022-02-28 16:43:50 -05:00
parent 2c12aaed1f
commit 6887035690
2 changed files with 57 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
gcc/lra-assigns.c
View File

@ -1773,8 +1773,8 @@ lra_split_hard_reg_for (void)
iterations. Either it's an asm and something is wrong with the
constraints, or we have run out of spill registers; error out in
either case. */
bool asm_p = false;
bitmap_head failed_reload_insns, failed_reload_pseudos;
bool asm_p = false, spill_p = false;
bitmap_head failed_reload_insns, failed_reload_pseudos, over_split_insns;
if (lra_dump_file != NULL)
fprintf (lra_dump_file,
@ -1785,6 +1785,7 @@ lra_split_hard_reg_for (void)
bitmap_ior (&non_reload_pseudos, &lra_inheritance_pseudos, &lra_split_regs);
bitmap_ior_into (&non_reload_pseudos, &lra_subreg_reload_pseudos);
bitmap_ior_into (&non_reload_pseudos, &lra_optional_reload_pseudos);
bitmap_initialize (&over_split_insns, &reg_obstack);
for (i = lra_constraint_new_regno_start; i < max_regno; i++)
if (reg_renumber[i] < 0 && lra_reg_info[i].nrefs != 0
&& (rclass = lra_get_allocno_class (i)) != NO_REGS
@ -1792,13 +1793,41 @@ lra_split_hard_reg_for (void)
{
if (! find_reload_regno_insns (i, first, last))
continue;
if (spill_hard_reg_in_range (i, rclass, first, last))
if (BLOCK_FOR_INSN (first) == BLOCK_FOR_INSN (last))
{
bitmap_clear (&failed_reload_pseudos);
return true;
/* Check that we are not trying to split over the same insn
requiring reloads to avoid splitting the same hard reg twice or
more. If we need several hard regs splitting over the same insn
it can be finished on the next iterations.
The following loop iteration number is small as we split hard
reg in a very small range. */
for (insn = first;
insn != NEXT_INSN (last);
insn = NEXT_INSN (insn))
if (bitmap_bit_p (&over_split_insns, INSN_UID (insn)))
break;
if (insn != NEXT_INSN (last)
|| !spill_hard_reg_in_range (i, rclass, first, last))
{
bitmap_set_bit (&failed_reload_pseudos, i);
}
else
{
for (insn = first;
insn != NEXT_INSN (last);
insn = NEXT_INSN (insn))
bitmap_set_bit (&over_split_insns, INSN_UID (insn));
spill_p = true;
}
}
bitmap_set_bit (&failed_reload_pseudos, i);
}
bitmap_clear (&over_split_insns);
if (spill_p)
{
bitmap_clear (&failed_reload_pseudos);
return true;
}
bitmap_clear (&non_reload_pseudos);
bitmap_initialize (&failed_reload_insns, &reg_obstack);
EXECUTE_IF_SET_IN_BITMAP (&failed_reload_pseudos, 0, u, bi)

22
gcc/testsuite/gcc.target/i386/pr104637.c Normal file
View File

@ -0,0 +1,22 @@
/* { dg-do compile } */
/* { dg-options "-Og -fno-forward-propagate -mavx" } */
typedef short __attribute__((__vector_size__ (64))) U;
typedef unsigned long long __attribute__((__vector_size__ (32))) V;
typedef long double __attribute__((__vector_size__ (64))) F;
int i;
U u;
F f;
void
foo (char a, char b, _Complex char c, V v)
{
u = (U) { u[0] / 0, u[1] / 0, u[2] / 0, u[3] / 0, u[4] / 0, u[5] / 0, u[6] / 0, u[7] / 0,
u[8] / 0, u[0] / 0, u[9] / 0, u[10] / 0, u[11] / 0, u[12] / 0, u[13] / 0, u[14] / 0, u[15] / 0,
u[16] / 0, u[17] / 0, u[18] / 0, u[19] / 0, u[20] / 0, u[21] / 0, u[22] / 0, u[23] / 0,
u[24] / 0, u[25] / 0, u[26] / 0, u[27] / 0, u[28] / 0, u[29] / 0, u[30] / 0, u[31] / 0 };
c += i;
f = (F) { v[0], v[1], v[2], v[3] };
i = (char) (__imag__ c + i);
}