[PATCH] Don't print discriminators for -fcompare-debug.

[Eugene Rozenfeld <Eugene.Rozenfeld@microsoft.com>]

With -gstatement-frontiers we may end up with different IR
coming from the front end with and without debug information turned on.
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100733 for details.
That may result in differences in discriminator values and -fcompare-debug
failures.

This patch disables printing of discriminators when the dump is intended
for -fcompare-debug comparison and reverses the workaround in a test.

Tested on x86_64-pc-linux-gnu.

gcc/ChangeLog:
	PR debug/107231
	PR debug/107169
	* print-rtl.cc (print_rtx_operand_code_i): Don't print discriminators
	for -fdebug-compare.

gcc/testsuite/ChangeLog:

	* c-c++-common/ubsan/pr85213.c: Reverse the workaround for discriminators.
---
 gcc/print-rtl.cc                           | 13 ++++++++++---
 gcc/testsuite/c-c++-common/ubsan/pr85213.c |  7 +------
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/gcc/print-rtl.cc b/gcc/print-rtl.cc
index e115f987173..0476f3d7e79 100644
--- a/gcc/print-rtl.cc
+++ b/gcc/print-rtl.cc
@@ -453,10 +453,17 @@ rtx_writer::print_rtx_operand_code_i (const_rtx in_rtx, int idx)
 	  expanded_location xloc = insn_location (in_insn);
 	  fprintf (m_outfile, " \"%s\":%i:%i", xloc.file, xloc.line,
 		   xloc.column);
-	  int discriminator = insn_discriminator (in_insn);
-	    if (discriminator)
-	      fprintf (m_outfile, " discrim %d", discriminator);
 
+	  /* Don't print discriminators for -fcompare-debug since the IR
+	     coming from the front end may be different with and without
+	     debug information turned on. That may result in different
+	     discriminator values. */
+	  if (!(dump_flags & TDF_COMPARE_DEBUG))
+	    {
+	      int discriminator = insn_discriminator (in_insn);
+	      if (discriminator)
+		fprintf (m_outfile, " discrim %d", discriminator);
+	    }
 	}
 #endif
     }
diff --git a/gcc/testsuite/c-c++-common/ubsan/pr85213.c b/gcc/testsuite/c-c++-common/ubsan/pr85213.c
index e903e976f2c..8a6be81d20f 100644
--- a/gcc/testsuite/c-c++-common/ubsan/pr85213.c
+++ b/gcc/testsuite/c-c++-common/ubsan/pr85213.c
@@ -1,11 +1,6 @@
 /* PR sanitizer/85213 */
 /* { dg-do compile } */
-/* Pass -gno-statement-frontiers to work around
-   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100733 :
-   without it the IR coming from the front end may be different with and without
-   debug information turned on. That may cause e.g., different discriminator values
-   and -fcompare-debug failures. */
-/* { dg-options "-O1 -fsanitize=undefined -fcompare-debug -gno-statement-frontiers" } */
+/* { dg-options "-O1 -fsanitize=undefined -fcompare-debug" } */
 
 int
 foo (int x)
-- 
2.25.1