commit 99ad7230ccaace93bf323dea9790f35fe991a4a2
author Razvan A Lupusoru <razvan.a.lupusoru@intel.com> Tue Feb 25 17:41:08 2014 -0800
committer Ian Rogers <irogers@google.com> Wed Mar 26 16:20:09 2014 -0700
tree 095705c674703953bf4c50f6a30a105420b770b5
parent a9e3d2ccfdbf7f4c7b1508bcb2b774037399b1d4

Relaxed memory barriers for x86

X86 provides stronger memory guarantees and thus the memory barriers can be
optimized. This patch ensures that all memory barriers for x86 are treated
as scheduling barriers. And in cases where a barrier is needed (StoreLoad case),
an mfence is used.

Change-Id: I13d02bf3f152083ba9f358052aedb583b0d48640
Signed-off-by: Razvan A Lupusoru <razvan.a.lupusoru@intel.com>

compiler/dex/quick/x86/assemble_x86.cc

diff --git a/compiler/dex/quick/x86/assemble_x86.cc b/compiler/dex/quick/x86/assemble_x86.cc
index 9cafcee..e7a1a69 100644
--- a/compiler/dex/quick/x86/assemble_x86.cc
+++ b/compiler/dex/quick/x86/assemble_x86.cc
@@ -344,6 +344,7 @@
   { kX86LockCmpxchgAR, kArrayReg, IS_STORE | IS_QUIN_OP | REG_USE014 | REG_DEFA_USEA | SETS_CCODES, { 0xF0, 0, 0x0F, 0xB1, 0, 0, 0, 0 }, "Lock Cmpxchg", "[!0r+!1r<<!2d+!3d],!4r" },
   { kX86LockCmpxchg8bM, kMem,   IS_STORE | IS_BINARY_OP | REG_USE0 | REG_DEFAD_USEAD | REG_USEC | REG_USEB | SETS_CCODES, { 0xF0, 0, 0x0F, 0xC7, 0, 1, 0, 0 }, "Lock Cmpxchg8b", "[!0r+!1d]" },
   { kX86LockCmpxchg8bA, kArray, IS_STORE | IS_QUAD_OP | REG_USE01 | REG_DEFAD_USEAD | REG_USEC | REG_USEB | SETS_CCODES, { 0xF0, 0, 0x0F, 0xC7, 0, 1, 0, 0 }, "Lock Cmpxchg8b", "[!0r+!1r<<!2d+!3d]" },
+  { kX86XchgMR, kMemReg, IS_STORE | IS_LOAD | IS_TERTIARY_OP | REG_DEF2 | REG_USE02, { 0, 0, 0x87, 0, 0, 0, 0, 0 }, "Xchg", "[!0r+!1d],!2r" },
 
   EXT_0F_ENCODING_MAP(Movzx8,  0x00, 0xB6, REG_DEF0),
   EXT_0F_ENCODING_MAP(Movzx16, 0x00, 0xB7, REG_DEF0),