[arm] PR target/82975: Guard against reg_renumber being NULL in arm.h

In this bug we ICE when checking REGNO_OK_FOR_INDEX_P on arm during pre-IRA scheduling.
This is because REGNO_OK_FOR_INDEX_P ends up checking the reg_renumber array.
Before IRA reg_renumber is NULL and thus we segfault.

The fix is to guard the use of reg_renumber in the logic in TEST_REGNO in arm.h.
On aarch64, for example, we also guard against the reg_renumber == NULL case.
This fixes the ICE. I also remove the part of the comment that muses on when reg_renumber
is available as with this patch it should now be safe to use at any point.

Bootstrapped and tested on arm-none-linux-gnueabihf.

	PR target/82975
	* config/arm/arm.h (TEST_REGNO): Check reg_renumber is set before
	accessing it.  Adjust comment.

	* gcc.dg/pr82975.c: New test.

From-SVN: r255830

gcc/ChangeLog

-2017-12-18  Jakub Jelinek  <jakub@redhat.com>
+2017-12-19  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+	PR target/82975
+	* config/arm/arm.h (TEST_REGNO): Check reg_renumber is set before
+	accessing it.  Adjust comment.
+
+2017-12-19  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/81914
 	* predict.c (zero_one_minusone): New function.

gcc/config/arm/arm.h

@@ -1620,7 +1620,8 @@ enum arm_auto_incmodes
    has been allocated, which happens in reginfo.c during register
    allocation.  */
 #define TEST_REGNO(R, TEST, VALUE) \
-  ((R TEST VALUE) || ((unsigned) reg_renumber[R] TEST VALUE))
+  ((R TEST VALUE)	\
+    || (reg_renumber && ((unsigned) reg_renumber[R] TEST VALUE)))
 
 /* Don't allow the pc to be used.  */
 #define ARM_REGNO_OK_FOR_BASE_P(REGNO)			\

gcc/testsuite/ChangeLog

+2017-12-19  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+	PR target/82975
+	* gcc.dg/pr82975.c: New test.
+
 2017-12-19  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/83489

gcc/testsuite/gcc.dg/pr82975.c

+/* PR target/82975.  */
+/* { dg-do compile } */
+/* { dg-options "-mtune=cortex-a57 -fno-sched-pressure -O2" } */
+
+typedef __SIZE_TYPE__ size_t;
+
+struct S1
+{
+  char pad1;
+  char val;
+  short pad2;
+};
+
+extern char t[256];
+
+void foo (struct S1 a, size_t i)
+{
+  t[i] = a.val;
+}