SkSplicer: fix aarch64 jump offset, turn on testing on aarch64 Android bots

I also updated the dump feature to work with aarch64, and included comments on how to disassemble an aarch64 dump.

Looking at an aarch64 dump made it immediately obvious that the jump offset was off by 1.

Change-Id: I17fa6ee44779e8be69ab4582e338c88212aba36c
Reviewed-on: https://skia-review.googlesource.com/6841
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

1 files changed, 14 insertions, 8 deletions

diff --git a/src/splicer/SkSplicer.cpp b/src/splicer/SkSplicer.cpp
index 789b3593e2..9fcb99c0fb 100644
--- a/src/splicer/SkSplicer.cpp
+++ b/src/splicer/SkSplicer.cpp
@@ -14,10 +14,16 @@
 #include "SkSplicer_generated.h"
 #include "SkSplicer_shared.h"
 
-// Uncomment to dump output with IACA markers.
-// #define IACA_DUMP "/tmp/dump.o"
-// https://software.intel.com/en-us/articles/intel-architecture-code-analyzer
-// $ ./iaca.sh -arch HSW -64 -mark 0 /tmp/dump.o | less
+// Uncomment to dump output JIT'd pipeline.
+//#define DUMP "/tmp/dump.bin"
+//
+// On x86, we'll include IACA markers too.
+//   https://software.intel.com/en-us/articles/intel-architecture-code-analyzer
+// Running IACA will disassemble, and more.
+//   $ ./iaca.sh -arch HSW -64 -mark 0 /tmp/dump.bin | less
+//
+// To disassemble an aarch64 dump,
+//   $ gobjdump -b binary -m aarch64 -D dump.bin
 
 namespace {
 
@@ -56,7 +62,7 @@ namespace {
     static void loop(SkWStream* buf, int loop_start) {
         splice(buf, 0x91001000);        // add x0, x0, #4
         splice(buf, 0xeb01001f);        // cmp x0, x1
-        int off = loop_start - (int)(buf->bytesWritten() + 4);  // TODO: check that this is right
+        int off = loop_start - (int)buf->bytesWritten();
         off /= 4;   // bytes -> instructions, still signed
         off = (off & 0x7ffff) << 5;  // 19 bit maximum range (+- 256K instructions)
         splice(buf, 0x54000003 | off); // b.cc loop_start  (cc == "carry clear", unsigned less than)
@@ -93,7 +99,7 @@ namespace {
     }
 #endif
 
-#ifdef IACA_DUMP
+#if !defined(__aarch64__) && defined(DUMP)
     static const uint8_t      ud2[] = { 0x0f, 0x0b };         // undefined... crashes when run
     static const uint8_t     nop3[] = { 0x64, 0x67, 0x90 };   // 3 byte no-op
     static const uint8_t movl_ebx[] = { 0xbb };               // move next 4 bytes into ebx
@@ -204,8 +210,8 @@ namespace {
             fSplicedLen = data->size();
             fSpliced    = copy_to_executable_mem(data->data(), fSplicedLen);
 
-        #ifdef IACA_DUMP
-            SkFILEWStream(IACA_DUMP).write(data->data(), data->size());
+        #if defined(DUMP)
+            SkFILEWStream(DUMP).write(data->data(), data->size());
         #endif
         }