S/390: Skip LT(G) peephole when literal pool is involved

By the time peephole optimizations run, we've already made up our mind
whether to use base-register or relative addressing for literal pool
entries.  LT(G) supports only base-register addressing, and so it is
too late to convert L(G)RL + compare to LT(G).  This change should not
make the code worse unless building with e.g. -fno-dce, since comparing
literal pool entries to zero should be optimized away during earlier
passes.

gcc/ChangeLog:

2018-11-20  Ilya Leoshkevich  <iii@linux.ibm.com>

	PR target/88083
	* config/s390/s390.md: Skip LT(G) peephole when literal pool is
	involved.
	* rtl.h (contains_constant_pool_address_p): New function.
	* rtlanal.c (contains_constant_pool_address_p): Likewise.

gcc/testsuite/ChangeLog:

2018-11-20  Ilya Leoshkevich  <iii@linux.ibm.com>

	PR target/88083
	* gcc.target/s390/pr88083.c: New test.

From-SVN: r266306

gcc/ChangeLog

+2018-11-20  Ilya Leoshkevich  <iii@linux.ibm.com>
+
+	PR target/88083
+	* config/s390/s390.md: Skip LT(G) peephole when literal pool is
+	involved.
+	* rtl.h (contains_constant_pool_address_p): New function.
+	* rtlanal.c (contains_constant_pool_address_p): Likewise.
+
 2018-11-20  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/83215

gcc/config/s390/s390.md

@@ -941,7 +941,8 @@
 	(compare (match_dup 0) (match_operand:GPR 1 "const0_operand")))]
   "s390_match_ccmode(insn, CCSmode) && TARGET_EXTIMM
    && GENERAL_REG_P (operands[0])
-   && satisfies_constraint_T (operands[2])"
+   && satisfies_constraint_T (operands[2])
+   && !contains_constant_pool_address_p (operands[2])"
   [(parallel
     [(set (reg:CCS CC_REGNUM)
 	  (compare:CCS (match_dup 2) (match_dup 1)))

gcc/rtl.h

@@ -3385,6 +3385,7 @@ extern void set_insn_deleted (rtx_insn *);
 extern rtx single_set_2 (const rtx_insn *, const_rtx);
 extern bool contains_symbol_ref_p (const_rtx);
 extern bool contains_symbolic_reference_p (const_rtx);
+extern bool contains_constant_pool_address_p (const_rtx);
 
 /* Handle the cheap and common cases inline for performance.  */
 

gcc/rtlanal.c

@@ -6551,6 +6551,20 @@ contains_symbolic_reference_p (const_rtx x)
   return false;
 }
 
+/* Return true if RTL X contains a constant pool address.  */
+
+bool
+contains_constant_pool_address_p (const_rtx x)
+{
+  subrtx_iterator::array_type array;
+  FOR_EACH_SUBRTX (iter, array, x, ALL)
+    if (SYMBOL_REF_P (*iter) && CONSTANT_POOL_ADDRESS_P (*iter))
+      return true;
+
+  return false;
+}
+
+
 /* Return true if X contains a thread-local symbol.  */
 
 bool

gcc/testsuite/ChangeLog

+2018-11-20  Ilya Leoshkevich  <iii@linux.ibm.com>
+
+	PR target/88083
+	* gcc.target/s390/pr88083.c: New test.
+
 2018-11-20  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/83215

gcc/testsuite/gcc.target/s390/pr88083.c

+/* { dg-do compile } */
+/* { dg-options "-fno-sched-last-insn-heuristic -fno-dce -march=z196 -O2" } */
+
+void *a, *b;
+
+void c(void)
+{
+  __builtin_memcpy(a, b, -1);  /* { dg-warning "exceeds maximum object size" } */
+}