From: Richard Sandiford <richard.sandiford@arm.com>
Date: Tue, 25 Jun 2024 17:02:35 +0000 (+0100)
Subject: late-combine: Honor targetm.cannot_copy_insn_p
X-Git-Tag: basepoints/gcc-16~7937
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b87e19afa349691fdc91173bcf7a9afc7b3b0cb1;p=thirdparty%2Fgcc.git

late-combine: Honor targetm.cannot_copy_insn_p

late-combine was failing to take targetm.cannot_copy_insn_p into
account, which led to multiple definitions of PIC symbols on
arm*-*-* targets.

gcc/
	* late-combine.cc (insn_combination::substitute_nondebug_use):
	Reject second and subsequent uses if targetm.cannot_copy_insn_p
	disallows copying.
---

diff --git a/gcc/late-combine.cc b/gcc/late-combine.cc
index fc75d1c56d7..b7c0bc07a8b 100644
--- a/gcc/late-combine.cc
+++ b/gcc/late-combine.cc
@@ -179,6 +179,18 @@ insn_combination::substitute_nondebug_use (use_info *use)
   if (dump_file && (dump_flags & TDF_DETAILS))
     dump_insn_slim (dump_file, use->insn ()->rtl ());
 
+  // Reject second and subsequent uses if the target does not allow
+  // the defining instruction to be copied.
+  if (targetm.cannot_copy_insn_p
+      && m_nondebug_changes.length () >= 2
+      && targetm.cannot_copy_insn_p (m_def_insn->rtl ()))
+    {
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, "-- The target does not allow multiple"
+		 " copies of insn %d\n", m_def_insn->uid ());
+      return false;
+    }
+
   // Check that we can change the instruction pattern.  Leave recognition
   // of the result till later.
   insn_propagation prop (use_rtl, m_dest, m_src);