Add support to do suspend polling on backward branches in JIT'ed code.

The polling is expensive for now as it is done through three
instructions: ld/ld/branch. As a result, a bunch of bonus stuff has
been worked on to mitigate the extra overhead:

- Cleaned up resource flags for memory disambiguation.
- Rewrote load/store elimination and scheduler routines to hide
  the ld/ld latency for GC flag. Seperate the dependency checking into
  memory disambiguation part and resource conflict part.
- Allowed code motion for Dalvik/constant/non-aliasing loads to be
  hoisted above branches for null/range checks.
- Created extended basic blocks following goto instructions so that
  longer instruction streams can be optimized as a whole.

Without the bonus stuff, the performance dropped about ~5-10% on some
benchmarks because of the lack of headroom to hide the polling latency
in tight loops. With the bonus stuff, the performance delta is between
+/-5% with polling code generated. With the bonus stuff but disabling
polling, the new bonus stuff provides consistent performance
improvements:

CaffeineMark  3.6%
Linpack      11.1%
Scimark       9.7%
Sieve        33.0%
Checkers      6.0%

As a result, GC polling is disabled by default but can be turned on
through the -Xjitsuspendpoll flag for experimental purposes.

Change-Id: Ia81fc85de3e2b70e6cc93bc37c2b845892003cdb

1 files changed, 12 insertions, 0 deletions

diff --git a/vm/compiler/codegen/arm/ArchUtility.c b/vm/compiler/codegen/arm/ArchUtility.c
index c6bcac2bc..be6d56b94 100644
--- a/vm/compiler/codegen/arm/ArchUtility.c
+++ b/vm/compiler/codegen/arm/ArchUtility.c
@@ -263,10 +263,22 @@ void dvmDumpResourceMask(LIR *lir, u8 mask, const char *prefix)
         if (mask & ENCODE_FP_STATUS) {
             strcat(buf, "fpcc ");
         }
+
+        /* Memory bits */
         if (armLIR && (mask & ENCODE_DALVIK_REG)) {
             sprintf(buf + strlen(buf), "dr%d%s", armLIR->aliasInfo & 0xffff,
                     (armLIR->aliasInfo & 0x80000000) ? "(+1)" : "");
         }
+        if (mask & ENCODE_LITERAL) {
+            strcat(buf, "lit ");
+        }
+
+        if (mask & ENCODE_HEAP_REF) {
+            strcat(buf, "heap ");
+        }
+        if (mask & ENCODE_MUST_NOT_ALIAS) {
+            strcat(buf, "noalias ");
+        }
     }
     if (buf[0]) {
         LOGD("%s: %s", prefix, buf);