Don't let DEBUG_INSNSs change register renaming decisions

	PR debug/94439
	* regrename.c (check_new_reg_p): Ignore DEBUG_INSNs when walking
	the chain.

	PR debug/94439
	* gcc.dg/torture/pr94439.c: New test.

gcc/ChangeLog

+2020-04-18  Jeff Law  <law@redhat.com>
+
+	PR debug/94439
+	* regrename.c (check_new_reg_p): Ignore DEBUG_INSNs when walking
+	the chain.
+
 2020-04-18  Iain Buclaw  <ibuclaw@gdcproject.org>
 
 	* doc/sourcebuild.texi (Effective-Target Keywords, Environment

gcc/regrename.c

@@ -348,11 +348,17 @@ check_new_reg_p (int reg ATTRIBUTE_UNUSED, int new_reg,
   /* See whether it accepts all modes that occur in
      definition and uses.  */
   for (tmp = this_head->first; tmp; tmp = tmp->next_use)
-    if ((!targetm.hard_regno_mode_ok (new_reg, GET_MODE (*tmp->loc))
-	 && ! DEBUG_INSN_P (tmp->insn))
+    {
+      /* Completely ignore DEBUG_INSNs, otherwise we can get
+	 -fcompare-debug failures.  */
+      if (DEBUG_INSN_P (tmp->insn))
+	continue;
+
+      if (!targetm.hard_regno_mode_ok (new_reg, GET_MODE (*tmp->loc))
 	  || call_clobbered_in_chain_p (this_head, GET_MODE (*tmp->loc),
 					new_reg))
 	return false;
+    }
 
   return true;
 }

gcc/testsuite/ChangeLog

+2020-04-18  Jeff Law  <law@redhat.com>
+
+	PR debug/94439
+	* gcc.dg/torture/pr94439.c: New test.
+
 2020-04-18  Iain Buclaw  <ibuclaw@gdcproject.org>
 
 	* gdc.dg/link.d: Use d_runtime_has_std_library effective target.

gcc/testsuite/gcc.dg/torture/pr94439.c

+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-additional-options "-flive-patching=inline-clone -funroll-loops -fno-tree-forwprop -fno-expensive-optimizations -mstack-arg-probe -fcompare-debug" } */
+/* { dg-skip-if "" { *-*-* } { "-flto" } { "" } } */
+
+extern void exit (int);
+extern void abort (void);
+
+#define COMPARE_BODY(A, B, TYPE, COPYSIGN)				\
+  do {									\
+    TYPE s1 = COPYSIGN ((TYPE) 1.0, A);					\
+    TYPE s2 = COPYSIGN ((TYPE) 1.0, B);					\
+    if (s1 != s2)							\
+      abort ();								\
+    if ((__builtin_isnan (A) != 0) != (__builtin_isnan (B) != 0))	\
+      abort ();								\
+    if ((A != B) != (__builtin_isnan (A) != 0))				\
+      abort ();								\
+  } while (0)
+
+void
+comparel (long double a, long double b)
+{
+  COMPARE_BODY (a, b, long double, __builtin_copysignl);
+}
+
+void
+comparecl (_Complex long double a, long double r, long double i)
+{
+  comparel (__real__ a, r);
+  comparel (__imag__ a, i);
+}
+
+#define VERIFY(A, B, TYPE, COMPARE)			\
+  do {							\
+    TYPE a = A;						\
+    TYPE b = B;						\
+    _Complex TYPE cr = __builtin_complex (a, b);	\
+    static _Complex TYPE cs = __builtin_complex (A, B);	\
+    COMPARE (cr, A, B);					\
+    COMPARE (cs, A, B);					\
+  } while (0)
+
+#define ALL_CHECKS(PZ, NZ, NAN, INF, TYPE, COMPARE)	\
+  do {							\
+    VERIFY (NAN, NZ, TYPE, COMPARE);			\
+    VERIFY (INF, NZ, TYPE, COMPARE);			\
+    VERIFY (INF, NAN, TYPE, COMPARE);			\
+    VERIFY (INF, INF, TYPE, COMPARE);			\
+  } while (0)
+
+void
+check_long_double (void)
+{
+  ALL_CHECKS (0.0l, -0.0l, __builtin_nanl(""), __builtin_infl(), long double, comparecl);
+}