Allow unaligned accesses for ARMv7.

src/arm/assembler-arm.cc

Index: src/arm/assembler-arm.cc
diff --git a/src/arm/assembler-arm.cc b/src/arm/assembler-arm.cc
index 7a65ab25cb745beafe7a371079440b2593a2753b..051eb72ec2afee0c4fcb0a1a9644994df3b18c55 100644
--- a/src/arm/assembler-arm.cc
+++ b/src/arm/assembler-arm.cc
@@ -77,6 +77,9 @@ static unsigned CpuFeaturesImpliedByCompiler() {
 #endif  // defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(__VFP_FP__)
         // && !defined(__SOFTFP__)
 #endif  // _arm__
+  if (answer & (1u << ARMv7)) {
+    answer |= 1u << UNALIGNED_ACCESSES;

[Michael Starzinger, 2012/10/10 11:11:19]

It seems the UNALIGNED_ACCESSES capability solely depends on the ARMv7
capability. Couldn't we just reuse the ARMv7 capability instead?

[ulan, 2012/10/10 12:13:28]

There could be non-ARMv7 processors that support this capability, but it is
difficult detect. For now, we just allow unaligned accesses for ARMv7.

We could alias UNALIGNED_ACCESSES to ARMv7, but IMO we should keep separate
names for capabilities.

+  }
 
   return answer;
 }
@@ -133,6 +136,10 @@ void CpuFeatures::Probe() {
     found_by_runtime_probing_ |= 1u << SUDIV;
   }
 
+  if (!IsSupported(UNALIGNED_ACCESSES) && OS::ArmCpuHasFeature(ARMv7)) {
+    found_by_runtime_probing_ |= 1u << UNALIGNED_ACCESSES;
+  }
+
   supported_ |= found_by_runtime_probing_;
 #endif