Fix libart-compiler ReadBarrier flag init order

`gCompilerReadBarrierOption` from libart-compiler depends on
`gUseReadBarrier` from libart. When both libraries are static linked, the
initialization order is not guaranteed to be correct.
The fix is to replace `gCompilerReadBarrierOption` with a function, so
that it is initialized on first use.

Test: m test-art-host-gtest
Test: m test-art-host-gtest (with static linked libart/libart-compiler)
Bug: 186902856
Change-Id: I386c64c3bd7b42391623b5cded5757366d847b3f

1 files changed, 6 insertions, 2 deletions

diff --git a/compiler/optimizing/code_generator.h b/compiler/optimizing/code_generator.h
index 9872efaa4a..576f363a67 100644
--- a/compiler/optimizing/code_generator.h
+++ b/compiler/optimizing/code_generator.h
@@ -59,8 +59,12 @@ static int32_t constexpr kPrimIntMax = 0x7fffffff;
 // Maximum value for a primitive long.
 static int64_t constexpr kPrimLongMax = INT64_C(0x7fffffffffffffff);
 
-static const ReadBarrierOption gCompilerReadBarrierOption =
-    gUseReadBarrier ? kWithReadBarrier : kWithoutReadBarrier;
+// Depending on configuration, `gUseReadBarrier` can be a static const variable.
+// Static variable initialization order across different compilation units is not defined,
+// so function is used instead of static variable `gCompilerReadBarrierOption`.
+inline ReadBarrierOption GetCompilerReadBarrierOption() {
+  return gUseReadBarrier ? kWithReadBarrier : kWithoutReadBarrier;
+}
 
 constexpr size_t status_lsb_position = SubtypeCheckBits::BitStructSizeOf();
 constexpr size_t status_byte_offset =