[PATCH] S/390: Run %a0:DI splitters only after reload

gcc/ChangeLog:

2019-10-15  Ilya Leoshkevich  <iii@linux.ibm.com>

	* config/s390/s390.md: Run %a0:DI splitters only after reload.

gcc/testsuite/ChangeLog:

2019-10-15  Ilya Leoshkevich  <iii@linux.ibm.com>

	* gcc.target/s390/load-thread-pointer-once.c: New test.

From-SVN: r276989

gcc/ChangeLog

+2019-10-15  Ilya Leoshkevich  <iii@linux.ibm.com>
+
+	* config/s390/s390.md: Run %a0:DI splitters only after reload.
+
 2019-10-15  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/92094

gcc/config/s390/s390.md

@@ -1860,10 +1860,17 @@
                               *,*,yes")
 ])
 
+; Splitters for loading/storing TLS pointers from/to %a0:DI.
+; Do this only during split2, which runs after reload. At the point when split1
+; runs, some of %a0:DI occurrences might be nested inside other rtxes and thus
+; not matched. As a result, only some occurrences will be split, which will
+; prevent CSE. At the point when split2 runs, reload will have ensured that no
+; nested references exist.
+
 (define_split
   [(set (match_operand:DI 0 "register_operand" "")
         (match_operand:DI 1 "register_operand" ""))]
-  "TARGET_ZARCH && ACCESS_REG_P (operands[1])"
+  "TARGET_ZARCH && ACCESS_REG_P (operands[1]) && reload_completed"
   [(set (match_dup 2) (match_dup 3))
    (set (match_dup 0) (ashift:DI (match_dup 0) (const_int 32)))
    (set (strict_low_part (match_dup 2)) (match_dup 4))]
@@ -1873,7 +1880,7 @@
 (define_split
   [(set (match_operand:DI 0 "register_operand" "")
         (match_operand:DI 1 "register_operand" ""))]
-  "TARGET_ZARCH && ACCESS_REG_P (operands[0])
+  "TARGET_ZARCH && ACCESS_REG_P (operands[0]) && reload_completed
    && dead_or_set_p (insn, operands[1])"
   [(set (match_dup 3) (match_dup 2))
    (set (match_dup 1) (lshiftrt:DI (match_dup 1) (const_int 32)))
@@ -1884,7 +1891,7 @@
 (define_split
   [(set (match_operand:DI 0 "register_operand" "")
         (match_operand:DI 1 "register_operand" ""))]
-  "TARGET_ZARCH && ACCESS_REG_P (operands[0])
+  "TARGET_ZARCH && ACCESS_REG_P (operands[0]) && reload_completed
    && !dead_or_set_p (insn, operands[1])"
   [(set (match_dup 3) (match_dup 2))
    (set (match_dup 1) (rotate:DI (match_dup 1) (const_int 32)))

gcc/testsuite/ChangeLog

+2019-10-15  Ilya Leoshkevich  <iii@linux.ibm.com>
+
+	* gcc.target/s390/load-thread-pointer-once.c: New test.
+
 2019-10-15  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/92094

gcc/testsuite/gcc.target/s390/load-thread-pointer-once.c

+/* { dg-do compile } */
+/* { dg-options "-O3" } */
+
+__thread void *foo;
+
+void *bar()
+{
+  return (foo = __builtin_thread_pointer());
+}
+
+/* { dg-final { scan-assembler-times {\n\tear\t} 2 { target { lp64 } } } } */
+/* { dg-final { scan-assembler-times {\n\tear\t} 1 { target { ! lp64 } } } } */