S/390: Don't unroll memory blk op loops

gcc/ChangeLog:

2018-08-06  Andreas Krebbel  <krebbel@linux.ibm.com>

	* config/s390/s390.c (s390_loop_unroll_adjust): Prevent small
	loops with memory block operations from getting unrolled.

gcc/testsuite/ChangeLog:

2018-08-06  Andreas Krebbel  <krebbel@linux.ibm.com>

	* gcc.target/s390/nomemloopunroll-1.c: New test.

From-SVN: r263336

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c36cffa366a1d82154a3927f3b9c128673a88241..b15d546f2a539dffa8cceccea832bab890a8f1f5 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2018-08-06  Andreas Krebbel  <krebbel@linux.ibm.com>
+
+       * config/s390/s390.c (s390_loop_unroll_adjust): Prevent small
+       loops with memory block operations from getting unrolled.
+
 2018-08-06  Ulrich Weigand  <uweigand@de.ibm.com>
 
        PR target/86807

diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c
index ec588a2e72e1f2028d73ef8864bceeccddb1d9a3..aa34f562dd82c6640adad34a5266fb3e32210cc6 100644 (file)
--- a/gcc/config/s390/s390.c
+++ b/gcc/config/s390/s390.c
@@ -390,6 +390,11 @@ static unsigned vfu_longrunning[NUM_SIDES];
    base and index are registers of the class ADDR_REGS,
    displacement is an unsigned 12-bit immediate constant.  */
 
+/* The max number of insns of backend generated memset/memcpy/memcmp
+   loops.  This value is used in the unroll adjust hook to detect such
+   loops.  Current max is 9 coming from the memcmp loop.  */
+#define BLOCK_MEM_OPS_LOOP_INSNS 9
+
 struct s390_address
 {
   rtx base;
@@ -15385,9 +15390,29 @@ s390_loop_unroll_adjust (unsigned nunroll, struct loop *loop)
   for (i = 0; i < loop->num_nodes; i++)
     FOR_BB_INSNS (bbs[i], insn)
       if (INSN_P (insn) && INSN_CODE (insn) != -1)
-       FOR_EACH_SUBRTX (iter, array, PATTERN (insn), NONCONST)
-         if (MEM_P (*iter))
-           mem_count += 1;
+       {
+         rtx set;
+
+         /* The runtime of small loops with memory block operations
+            will be determined by the memory operation.  Doing
+            unrolling doesn't help here.  Measurements to confirm
+            this where only done on recent CPU levels.  So better do
+            not change anything for older CPUs.  */
+         if (s390_tune >= PROCESSOR_2964_Z13
+             && loop->ninsns <= BLOCK_MEM_OPS_LOOP_INSNS
+             && ((set = single_set (insn)) != NULL_RTX)
+             && ((GET_MODE (SET_DEST (set)) == BLKmode
+                  && (GET_MODE (SET_SRC (set)) == BLKmode
+                      || SET_SRC (set) == const0_rtx))
+                 || (GET_CODE (SET_SRC (set)) == COMPARE
+                     && GET_MODE (XEXP (SET_SRC (set), 0)) == BLKmode
+                     && GET_MODE (XEXP (SET_SRC (set), 1)) == BLKmode)))
+           return 1;
+
+         FOR_EACH_SUBRTX (iter, array, PATTERN (insn), NONCONST)
+           if (MEM_P (*iter))
+             mem_count += 1;
+       }
   free (bbs);
 
   /* Prevent division by zero, and we do not need to adjust nunroll in this case.  */

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index fb65bd04effa3ad96670e966280faca81b398e6c..0d8fc74b16ab8c4b3301f235b66861ec563d63e3 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2018-08-06  Andreas Krebbel  <krebbel@linux.ibm.com>
+
+       * gcc.target/s390/nomemloopunroll-1.c: New test.
+
 2018-08-05  H.J. Lu  <hongjiu.lu@intel.com>
 
        PR target/86386

diff --git a/gcc/testsuite/gcc.target/s390/nomemloopunroll-1.c b/gcc/testsuite/gcc.target/s390/nomemloopunroll-1.c
new file mode 100644 (file)
index 0000000..695d925
--- /dev/null
+++ b/gcc/testsuite/gcc.target/s390/nomemloopunroll-1.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -funroll-loops -march=z13" } */
+
+/* 2x mvc */
+void *
+foo (char *a, int c, long len)
+{
+  return __builtin_memset (a, c, len);
+}
+
+/* 2x mvc */
+void
+bar (char *a, char *b)
+{
+  __builtin_memcpy (a, b, 30000);
+}
+
+/* 2x clc */
+
+int
+baz (char *a, char *b)
+{
+  return __builtin_memcmp (a, b, 30000);
+}
+
+/* { dg-final { scan-assembler-times "\\\smvc\\\s" 4 } } */
+/* { dg-final { scan-assembler-times "\\\sclc\\\s" 2 } } */