47 lines
1.4 KiB
Diff
47 lines
1.4 KiB
Diff
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From 5729ffad4db78b26f0d1f658a9fd695be5970550 Mon Sep 17 00:00:00 2001
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From: Richard Biener <rguenther@suse.de>
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Date: Wed, 3 Apr 2024 12:58:26 +0200
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Subject: [PATCH] rtl-optimization/101523 - avoid re-combine after noop 2->2
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combination
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To: gcc-patches@gcc.gnu.org
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The following avoids re-walking and re-combining the instructions
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between i2 and i3 when the pattern of i2 doesn't change.
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PR rtl-optimization/101523
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* combine.cc (try_combine): When the pattern of i2 doesn't
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change do not re-start combining at i2 or an earlier insn which
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had links or notes added.
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---
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gcc/combine.cc | 7 +++++++
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1 file changed, 7 insertions(+)
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diff --git a/gcc/combine.cc b/gcc/combine.cc
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index a4479f8d836..ff25752cac4 100644
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--- a/gcc/combine.cc
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+++ b/gcc/combine.cc
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@@ -4186,6 +4186,10 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn *i1, rtx_insn *i0,
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adjust_for_new_dest (i3);
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}
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+ bool i2_unchanged = false;
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+ if (rtx_equal_p (newi2pat, PATTERN (i2)))
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+ i2_unchanged = true;
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+
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/* We now know that we can do this combination. Merge the insns and
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update the status of registers and LOG_LINKS. */
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@@ -4752,6 +4756,9 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn *i1, rtx_insn *i0,
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combine_successes++;
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undo_commit ();
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+ if (i2_unchanged)
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+ return i3;
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+
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rtx_insn *ret = newi2pat ? i2 : i3;
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if (added_links_insn && DF_INSN_LUID (added_links_insn) < DF_INSN_LUID (ret))
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ret = added_links_insn;
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--
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2.35.3
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