changeset 35841:39f8dc1df42b

8149365: aarch64: memory copy does not prefetch on backwards copy Summary: Implement prefetch on backwards copies Reviewed-by: aph
author enevill
date Mon, 08 Feb 2016 14:14:35 +0000
parents e77862fd1bcf
children 1d34635308b0
files hotspot/src/cpu/aarch64/vm/stubGenerator_aarch64.cpp hotspot/src/cpu/aarch64/vm/vm_version_aarch64.cpp
diffstat 2 files changed, 19 insertions(+), 3 deletions(-) [+]
line wrap: on
line diff
--- a/hotspot/src/cpu/aarch64/vm/stubGenerator_aarch64.cpp	Thu Feb 04 16:24:28 2016 +0000
+++ b/hotspot/src/cpu/aarch64/vm/stubGenerator_aarch64.cpp	Mon Feb 08 14:14:35 2016 +0000
@@ -786,6 +786,7 @@
     int offset;
     const Register t0 = r3, t1 = r4, t2 = r5, t3 = r6,
       t4 = r7, t5 = r10, t6 = r11, t7 = r12;
+    const Register stride = r13;
 
     assert_different_registers(rscratch1, t0, t1, t2, t3, t4, t5, t6, t7);
     assert_different_registers(s, d, count, rscratch1);
@@ -845,10 +846,18 @@
     __ ldp(t4, t5, Address(s, 6 * unit));
     __ ldp(t6, t7, Address(__ pre(s, 8 * unit)));
 
+    int prefetch = PrefetchCopyIntervalInBytes;
+    bool use_stride = false;
+    if (direction == copy_backwards) {
+       use_stride = prefetch > 256;
+       prefetch = -prefetch;
+       if (use_stride) __ mov(stride, prefetch);
+    }
+
     __ bind(again);
 
-    if (direction == copy_forwards && PrefetchCopyIntervalInBytes > 0)
-      __ prfm(Address(s, PrefetchCopyIntervalInBytes), PLDL1KEEP);
+    if (PrefetchCopyIntervalInBytes > 0)
+      __ prfm(use_stride ? Address(s, stride) : Address(s, prefetch), PLDL1KEEP);
 
     __ stp(t0, t1, Address(d, 2 * unit));
     __ ldp(t0, t1, Address(s, 2 * unit));
--- a/hotspot/src/cpu/aarch64/vm/vm_version_aarch64.cpp	Thu Feb 04 16:24:28 2016 +0000
+++ b/hotspot/src/cpu/aarch64/vm/vm_version_aarch64.cpp	Mon Feb 08 14:14:35 2016 +0000
@@ -120,7 +120,14 @@
     FLAG_SET_DEFAULT(AllocatePrefetchStepSize, 64);
   FLAG_SET_DEFAULT(PrefetchScanIntervalInBytes, 256);
   FLAG_SET_DEFAULT(PrefetchFieldsAhead, 256);
-  FLAG_SET_DEFAULT(PrefetchCopyIntervalInBytes, 256);
+  if (FLAG_IS_DEFAULT(PrefetchCopyIntervalInBytes))
+    FLAG_SET_DEFAULT(PrefetchCopyIntervalInBytes, 256);
+  if ((PrefetchCopyIntervalInBytes & 7) || (PrefetchCopyIntervalInBytes >= 32768)) {
+    warning("PrefetchCopyIntervalInBytes must be a multiple of 8 and < 32768");
+    PrefetchCopyIntervalInBytes &= ~7;
+    if (PrefetchCopyIntervalInBytes >= 32768)
+      PrefetchCopyIntervalInBytes = 32760;
+  }
 
   unsigned long auxv = getauxval(AT_HWCAP);