[PR89528] reset debug uses of return value when dropping dead RTL call

When we remove an RTL call, we wouldn't clean up references to the
return value of the call in debug insns.  Make it so that we do.


for  gcc/ChangeLog

	PR debug/89528
	* valtrack.c (dead_debug_insert_temp): Reset debug references
	to the return value of a call being removed.

for  gcc/testsuite/ChangeLog

	PR debug/89528
	* gcc.dg/guality/pr89528.c: New.

From-SVN: r270389

gcc/ChangeLog

+2019-04-16  Alexandre Oliva <aoliva@redhat.com>
+
+	PR debug/89528
+	* valtrack.c (dead_debug_insert_temp): Reset debug references
+	to the return value of a call being removed.
+
 2019-04-16  Claudiu Zissulescu  <claziss@synopsys.com>
 
 	* config/arc/arc-protos.h (arc_register_move_cost): Remove.

gcc/testsuite/ChangeLog

 2019-04-16  Alexandre Oliva <aoliva@redhat.com>
 
+	PR debug/89528
+	* gcc.dg/guality/pr89528.c: New.
+
 	PR rtl-optimization/86438
 	* gcc.dg/torture/pr86438.c: Split up too-wide shift.
 

gcc/testsuite/gcc.dg/guality/pr89528.c

+/* PR debug/89528 */
+/* { dg-do run } */
+/* { dg-options "-g" } */
+
+#include <stdio.h>
+
+char b;
+int d, e;
+static int i = 1;
+void a(int l) { printf("", l); }
+char c(char l) { return l || b && l == 1 ? b : b % l; }
+short f(int l, int m) { return l * m; }
+short g(short l, short m) { return m || l == 767 && m == 1; }
+int h(int l, int m) { return (l ^ m & l ^ (m & 647) - m ^ m) < m; }
+static int j(int l) { return d == 0 || l == 647 && d == 1 ? l : l % d; }
+short k(int l) { return l >= 2 >> l; }
+void optimize_me_not() { asm(""); }
+static short n(void) {
+  int l_1127 = ~j(9 || 0) ^ 65535;
+  optimize_me_not(); /* { dg-final { gdb-test . "l_1127+1" "-65534" } } */
+  f(l_1127, i && e ^ 4) && g(0, 0);
+  e = 0;
+  return 5;
+}
+int main() { n(); }

gcc/valtrack.c

@@ -657,22 +657,12 @@ dead_debug_insert_temp (struct dead_debug_local *debug, unsigned int uregno,
 	{
 	  dest = SET_DEST (set);
 	  src = SET_SRC (set);
-	  /* Lose if the REG-setting insn is a CALL.  */
-	  if (GET_CODE (src) == CALL)
-	    {
-	      while (uses)
-		{
-		  cur = uses->next;
-		  XDELETE (uses);
-		  uses = cur;
-		}
-	      return 0;
-	    }
-	  /* Asm in DEBUG_INSN is never useful, we can't emit debug info for
-	     that.  And for volatile_insn_p, it is actually harmful
-	     - DEBUG_INSNs shouldn't have any side-effects.  */
-	  else if (GET_CODE (src) == ASM_OPERANDS
-		   || volatile_insn_p (src))
+	  /* Reset uses if the REG-setting insn is a CALL.  Asm in
+	     DEBUG_INSN is never useful, we can't emit debug info for
+	     that.  And for volatile_insn_p, it is actually harmful -
+	     DEBUG_INSNs shouldn't have any side-effects.  */
+	  if (GET_CODE (src) == CALL || GET_CODE (src) == ASM_OPERANDS
+	      || volatile_insn_p (src))
 	    set = NULL_RTX;
 	}