[InstrProfiling] Support relative CountersPtr for PlatformOther

[jsji]

Summary

D104556 change the CountersPtr to be relative, however, it did not
update the pointer initialization in llvm_profile_register_function,
so the platform (eg:AIX) that use llvm_profile_register_function is now totaly
broken, any PGO code will SEGV.

This patch update the code to reflect that the Data->CountersPtr is now
relative.

[jsji]

Unfortunately, looks like we haven't enabled any of the test in compiler-rt/test/profile for AIX, as it allows the host_os in whilelist only, which was not noticed before.
We will work on enable those tests in AIX, probably in another patch.

Appreciate if there is some specific lit test can be added to test this behavior, I can add that first. Thanks.

[davidxl]

Can you modify lit.cfg.py file to add AIX in supported host platforms and start from there?

[jsji]

In D108304#2952462, @davidxl wrote:

Can you modify lit.cfg.py file to add AIX in supported host platforms and start from there?

Thanks David, yes, that's what I am working on, so far there are only a few of them passing. I plan to work on porting those in following patches. Is that OK?

For this patch, I have verified that it works on our spec build.

[hubert.reinterpretcast]

compiler-rt/lib/profile/InstrProfilingPlatformOther.c

49–50

I suggest keeping "base + offset" expressions with the "base" first (in left-to-right order).
Also, should D104556 not have changed the name of the CounterPtr member?

[davidxl]

LGTM -- with Hubert's suggestions addressed.

[jsji]

Address comments.

compiler-rt/lib/profile/InstrProfilingPlatformOther.c

  */
 COMPILER_RT_VISIBILITY
 void __llvm_profile_register_function(void *Data_) {
   /* TODO: Only emit this function if we can't use linker magic. */
   const __llvm_profile_data *Data = (__llvm_profile_data *)Data_;
   if (!DataFirst) {
     DataFirst = Data;
     DataLast = Data + 1;
-    CountersFirst = Data->CounterPtr;
-    CountersLast = (uint64_t *)Data->CounterPtr + Data->NumCounters;
+    CountersFirst = (uint64_t *)((uintptr_t)Data_ + Data->CounterPtr);
+    CountersLast = CountersFirst + Data->NumCounters;
     return;
   }
 
   DataFirst = (const __llvm_profile_data *)getMinAddr(DataFirst, Data);
-  CountersFirst = (uint64_t *)getMinAddr(CountersFirst, Data->CounterPtr);
+  CountersFirst = (uint64_t *)getMinAddr(
+      CountersFirst, (uint64_t *)((uintptr_t)Data_ + Data->CounterPtr));
 
   DataLast = (const __llvm_profile_data *)getMaxAddr(DataLast, Data + 1);
   CountersLast = (uint64_t *)getMaxAddr(
-      CountersLast, (uint64_t *)Data->CounterPtr + Data->NumCounters);
+      CountersLast,
+      (uint64_t *)((uintptr_t)Data_ + Data->CounterPtr) + Data->NumCounters);
 }
 
 COMPILER_RT_VISIBILITY
 void __llvm_profile_register_names_function(void *NamesStart,
                                             uint64_t NamesSize) {
   if (!NamesFirst) {
     NamesFirst = (const char *)NamesStart;
     NamesLast = (const char *)NamesStart + NamesSize;