[gcc r11-9897] emit-rtl: Fix -fcompare-debug bug with label references in debug insns [PR105203]

[gcc r11-9897] emit-rtl: Fix -fcompare-debug bug with label references in debug insns [PR105203]

[Jakub Jelinek]

https://gcc.gnu.org/g:141b66c4becfa2f2c09b4a6cc0411d995ea5153a

commit r11-9897-g141b66c4becfa2f2c09b4a6cc0411d995ea5153a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Apr 21 09:43:30 2022 +0200

    emit-rtl: Fix -fcompare-debug bug with label references in debug insns [PR105203]
    
    When we compute LABEL_NUSES from scratch, mark_all_labels doesn't call
    mark_jump_label on DEBUG_INSNs:
                  if (NONDEBUG_INSN_P (insn))
                    mark_jump_label (PATTERN (insn), insn, 0);
    and so doesn't increment LABEL_NUSES from references in DEBUG_INSNs.
    But, when we call emit_copy_of_insn_after e.g. when duplicating some
    DEBUG_INSNs, we call it even on those, which then results in LABEL_NUSES
    differences and -fcompare-debug failures.
    
    The following patch makes sure we don't call it on DEBUG_INSNs.
    
    2022-04-21  Jakub Jelinek  <jakub@redhat.com>
    
            PR debug/105203
            * emit-rtl.c (emit_copy_of_insn_after): Don't call mark_jump_label
            on DEBUG_INSNs.
    
            * gfortran.dg/g77/pr105203.f: New test.
    
    (cherry picked from commit 504b02c70abcc31e0e9b56e69f82f85b5261bca9)

Diff:
---
 gcc/emit-rtl.c                           |  3 ++-
 gcc/testsuite/gfortran.dg/g77/pr105203.f | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index 07e908624a0..0dc51220682 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -6465,7 +6465,8 @@ emit_copy_of_insn_after (rtx_insn *insn, rtx_insn *after)
     }
 
   /* Update LABEL_NUSES.  */
-  mark_jump_label (PATTERN (new_rtx), new_rtx, 0);
+  if (NONDEBUG_INSN_P (insn))
+    mark_jump_label (PATTERN (new_rtx), new_rtx, 0);
 
   INSN_LOCATION (new_rtx) = INSN_LOCATION (insn);
 
diff --git a/gcc/testsuite/gfortran.dg/g77/pr105203.f b/gcc/testsuite/gfortran.dg/g77/pr105203.f
new file mode 100644
index 00000000000..3b47210fb40
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/g77/pr105203.f
@@ -0,0 +1,20 @@
+C Test case for PR debug/105203
+C Origin: kmccarty@princeton.edu
+C
+C { dg-do compile }
+C { dg-options "-O2 -fcompare-debug -ftracer -w" }
+C { dg-additional-options "-fPIC" { target fpic } }
+      SUBROUTINE FOO (B)
+
+  10  CALL BAR (A)
+      ASSIGN 20 TO M
+      IF (100.LT.A) GOTO 10
+      GOTO 40
+C
+  20  IF (B.LT.ABS(A)) GOTO 10
+      ASSIGN 30 TO M
+      GOTO 40
+C
+  30  ASSIGN 10 TO M
+  40  GOTO M,(10,20,30)
+      END