[XRay][Arm] Enable back XRay testing on Arm32 and fix the failing tests

Summary:
Testing of XRay was occasionally disabled on 32-bit Arm targets (someone assumed that XRay was supported on 64-bit targets only). This patch should fix that problem. Also here the instruction&data cache incoherency problem is fixed, because it may be causing a test to fail.
This patch is one of a series: see also
- https://reviews.llvm.org/D28624

Reviewers: dberris, rengolin

Reviewed By: rengolin

Subscribers: llvm-commits, aemerson, rengolin, dberris, iid_iunknown

Differential Revision: https://reviews.llvm.org/D28623

llvm-svn: 292517

compiler-rt/lib/xray/xray_arm.cc

@@ -19,6 +19,8 @@
 #include <atomic>
 #include <cassert>
 
+extern "C" void __clear_cache(void* start, void* end);
+
 namespace __xray {
 
 uint64_t cycleFrequency() XRAY_NEVER_INSTRUMENT {
@@ -116,15 +118,16 @@ inline static bool patchSled(const bool Enable, const uint32_t FuncId,
   //   B #20
 
   uint32_t *FirstAddress = reinterpret_cast<uint32_t *>(Sled.Address);
+  uint32_t *CurAddress = FirstAddress + 1;
   if (Enable) {
-    uint32_t *CurAddress = FirstAddress + 1;
     CurAddress =
         Write32bitLoadR0(CurAddress, reinterpret_cast<uint32_t>(FuncId));
     CurAddress =
         Write32bitLoadIP(CurAddress, reinterpret_cast<uint32_t>(TracingHook));
     *CurAddress = uint32_t(PatchOpcodes::PO_BlxIp);
     CurAddress++;
     *CurAddress = uint32_t(PatchOpcodes::PO_PopR0Lr);
+    CurAddress++;
     std::atomic_store_explicit(
         reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress),
         uint32_t(PatchOpcodes::PO_PushR0Lr), std::memory_order_release);
@@ -133,6 +136,8 @@ inline static bool patchSled(const bool Enable, const uint32_t FuncId,
         reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress),
         uint32_t(PatchOpcodes::PO_B20), std::memory_order_release);
   }
+  __clear_cache(reinterpret_cast<char*>(FirstAddress),
+      reinterpret_cast<char*>(CurAddress));
   return true;
 }
 

compiler-rt/test/xray/lit.cfg

@@ -30,8 +30,14 @@ config.substitutions.append(
 # Default test suffixes.
 config.suffixes = ['.c', '.cc', '.cpp']
 
-if config.host_os not in ['Linux'] or config.host_arch.find('64') == -1:
+if config.host_os not in ['Linux']:
   config.unsupported = True
+elif '64' not in config.host_arch:
+  if 'arm' in config.host_arch:
+    if '-mthumb' in config.target_cflags:
+      config.unsupported = True
+  else:
+    config.unsupported = True
 
 # Allow tests to use REQUIRES=stable-runtime.  For use when you cannot use XFAIL
 # e.g. because the test sometimes passes, sometimes fails.