On 03/15/2017 12:09 AM, Bernd Schmidt wrote:
I'll retest with your
suggestion and with the bitmap creation conditional on i1 being nonnull.
Like this (also had to throw in a bitmap_empty_p). Retested as before. Ok?
Bernd
Index: gcc/combine.c
===================================================================
--- gcc/combine.c (revision 245685)
+++ gcc/combine.c (working copy)
@@ -104,6 +104,7 @@ along with GCC; see the file COPYING3.
#include "valtrack.h"
#include "rtl-iter.h"
#include "print-rtl.h"
+#include "dbgcnt.h"
/* Number of attempts to combine instructions in this function. */
@@ -2559,6 +2560,57 @@ can_split_parallel_of_n_reg_sets (rtx_in
return true;
}
+/* Set up a set of registers used in an insn. Called through note_uses,
+ arguments as described for that function. */
+
+static void
+record_used_regs (rtx *xptr, void *data)
+{
+ bitmap set = (bitmap)data;
+ int i, j;
+ enum rtx_code code;
+ const char *fmt;
+ rtx x = *xptr;
+
+ /* repeat is used to turn tail-recursion into iteration since GCC
+ can't do it when there's no return value. */
+ repeat:
+ if (x == 0)
+ return;
+
+ code = GET_CODE (x);
+ if (REG_P (x))
+ {
+ unsigned regno = REGNO (x);
+ unsigned end_regno = END_REGNO (x);
+ while (regno < end_regno)
+ bitmap_set_bit (set, regno++);
+ return;
+ }
+
+ /* Recursively scan the operands of this expression. */
+
+ for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
+ {
+ if (fmt[i] == 'e')
+ {
+ /* If we are about to do the last recursive call
+ needed at this level, change it into iteration.
+ This function is called enough to be worth it. */
+ if (i == 0)
+ {
+ x = XEXP (x, 0);
+ goto repeat;
+ }
+
+ record_used_regs (&XEXP (x, i), data);
+ }
+ else if (fmt[i] == 'E')
+ for (j = 0; j < XVECLEN (x, i); j++)
+ record_used_regs (&XVECEXP (x, i, j), data);
+ }
+}
+
/* Try to combine the insns I0, I1 and I2 into I3.
Here I0, I1 and I2 appear earlier than I3.
I0 and I1 can be zero; then we combine just I2 into I3, or I1 and I2 into
@@ -2742,6 +2794,27 @@ try_combine (rtx_insn *i3, rtx_insn *i2,
added_links_insn = 0;
+ /* For combinations that may result in two insns, we have to gather
+ some extra information about registers used, so that we can
+ update all relevant LOG_LINKS later. */
+ auto_bitmap i2_regset, i3_regset, links_regset;
+ if (i1)
+ {
+ note_uses (&PATTERN (i2), record_used_regs, (bitmap)i2_regset);
+ note_uses (&PATTERN (i3), record_used_regs, (bitmap)i3_regset);
+ insn_link *ll;
+ FOR_EACH_LOG_LINK (ll, i3)
+ bitmap_set_bit (links_regset, ll->regno);
+ FOR_EACH_LOG_LINK (ll, i2)
+ bitmap_set_bit (links_regset, ll->regno);
+ if (i1)
+ FOR_EACH_LOG_LINK (ll, i1)
+ bitmap_set_bit (links_regset, ll->regno);
+ if (i0)
+ FOR_EACH_LOG_LINK (ll, i0)
+ bitmap_set_bit (links_regset, ll->regno);
+ }
+
/* First check for one important special case that the code below will
not handle. Namely, the case where I1 is zero, I2 is a PARALLEL
and I3 is a SET whose SET_SRC is a SET_DEST in I2. In that case,
@@ -4004,6 +4077,12 @@ try_combine (rtx_insn *i3, rtx_insn *i2,
}
}
+ if (!dbg_cnt (combine))
+ {
+ undo_all ();
+ return 0;
+ }
+
/* If it still isn't recognized, fail and change things back the way they
were. */
if ((insn_code_number < 0
@@ -4051,6 +4130,33 @@ try_combine (rtx_insn *i3, rtx_insn *i2,
return 0;
}
+ auto_bitmap new_regs_in_i2;
+ if (newi2pat)
+ {
+ /* We need to discover situations where we introduce a use of a
+ register into I2, where none of the existing LOG_LINKS contain
+ a reference to it. This can happen if previously I3 referenced
+ the reg, and there is an additional use between I2 and I3. We
+ must remove the LOG_LINKS entry from that additional use and
+ distribute it along with our own ones. */
+ note_uses (&newi2pat, record_used_regs, (bitmap)new_regs_in_i2);
+ bitmap_and_compl_into (new_regs_in_i2, i2_regset);
+ bitmap_and_compl_into (new_regs_in_i2, links_regset);
+
+ /* Here, we first look for situations where a hard register use
+ moved, and just give up. This should happen approximately
+ never, and it's not worth it to deal with possibilities like
+ multi-word registers. Later, when fixing up LOG_LINKS, we
+ deal with the case where a pseudo use moved. */
+ if (!bitmap_empty_p (new_regs_in_i2)
+ && prev_nonnote_insn (i3) != i2
+ && bitmap_first_set_bit (new_regs_in_i2) < FIRST_PSEUDO_REGISTER)
+ {
+ undo_all ();
+ return 0;
+ }
+ }
+
if (MAY_HAVE_DEBUG_INSNS)
{
struct undo *undo;
@@ -4494,6 +4600,45 @@ try_combine (rtx_insn *i3, rtx_insn *i2,
NULL_RTX, NULL_RTX, NULL_RTX);
}
+ if (newi2pat)
+ {
+ bitmap_iterator iter;
+ unsigned int i;
+
+ /* See comments above where we calculate the bitmap. */
+ EXECUTE_IF_SET_IN_BITMAP ((bitmap)new_regs_in_i2,
+ LAST_VIRTUAL_REGISTER, i, iter)
+ {
+ rtx reg = regno_reg_rtx[i];
+ rtx_insn *other;
+ for (other = NEXT_INSN (i2); other != i3; other = NEXT_INSN (other))
+ if (NONDEBUG_INSN_P (other)
+ && (reg_overlap_mentioned_p (reg, PATTERN (other))
+ || (CALL_P (other) && find_reg_fusage (other, USE, reg))))
+ {
+ if (dump_file)
+ fprintf (dump_file,
+ "found extra use of reg %d at insn %d\n", i,
+ INSN_UID (other));
+ insn_link **plink;
+ for (plink = &LOG_LINKS (other);
+ *plink;
+ plink = &(*plink)->next)
+ {
+ insn_link *link = *plink;
+ if (link->regno == i)
+ {
+ *plink = link->next;
+ link->next = i3links;
+ i3links = link;
+ break;
+ }
+ }
+ break;
+ }
+ }
+ }
+
distribute_links (i3links);
distribute_links (i2links);
distribute_links (i1links);
