[AIX] Add threadId and use nanosecond timestamp in sinit/sterm symbols

[w2yehia]

Summary

With ThinLTO, when compiling SPEC 2017 omnetpp_r with -threads=4, two small modules can end up with the same timestamp in their sinit symbols when calculating time in seconds, creating duplicate definitions.

This patch uses a timestamp in nanoseconds.
Because the race can be between threads, embed the thread ID as well.

[xingxue]

LGTM, provided the CI is clean.

[daltenty]

Repeating some offline discussion: fundamentally the issue is a race between backend threads in thinLTO, so we might want to consider adding a thread ID

[w2yehia]

address code review comments,

[daltenty]

LGTM, thanks!

[xingxue]

Confirm LGTM.

[lhames]

@w2yehia Looks like this broke https://green.lab.llvm.org/green/job/clang-stage1-RA/35559/. Could you please take a look?

[w2yehia]

In D159319#4641304, @lhames wrote:

@w2yehia Looks like this broke https://green.lab.llvm.org/green/job/clang-stage1-RA/35559/. Could you please take a look?

@lhames, checking

[thakis]

This breaks building on Mac: http://45.33.8.238/macm1/68693/step_4.txt

Please take a look and revert for now if it takes a while to fix.

llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp

 #include "llvm/MC/TargetRegistry.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/CodeGen.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/thread.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/TargetParser/Triple.h"
 #include "llvm/Transforms/Utils/ModuleUtils.h"
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
 #include <memory>
 #include <new>
if (isSpecialLLVMGlobalArrayForStaticInit(&G)) {
       // the sinit and sterm function names.
       if (FormatIndicatorAndUniqueModId.empty()) {
         std::string UniqueModuleId = getUniqueModuleId(&M);
         if (UniqueModuleId != "")
           // TODO: Use source file full path to generate the unique module id
           // and add a format indicator as a part of function name in case we
           // will support more than one format.
           FormatIndicatorAndUniqueModId = "clang_" + UniqueModuleId.substr(1);
-        else
-          // Use the Pid and current time as the unique module id when we cannot
-          // generate one based on a module's strong external symbols.
-          // FIXME: Adjust the comment accordingly after we use source file full
-          // path instead.
+        else {
+          // Use threadId, Pid, and current time as the unique module id when we
+          // cannot generate one based on a module's strong external symbols.
+          auto CurTime =
+              std::chrono::duration_cast<std::chrono::nanoseconds>(
+                  std::chrono::steady_clock::now().time_since_epoch())
+                  .count();
           FormatIndicatorAndUniqueModId =
-              "clangPidTime_" + llvm::itostr(sys::Process::getProcessId()) +
-              "_" + llvm::itostr(time(nullptr));
+              "clangPidTidTime_" + llvm::itostr(sys::Process::getProcessId()) +
+              "_" + llvm::itostr(llvm::this_thread::get_id()) + "_" +
+              llvm::itostr(CurTime);
+        }
       }
 
       emitSpecialLLVMGlobal(&G);
       continue;
     }
 
     setCsectAlignment(&G);
   }

llvm/test/CodeGen/PowerPC/aix-static-init-no-unique-module-id.ll

 ; RUN: llc -mtriple powerpc-ibm-aix-xcoff < %s | FileCheck %s
 ; RUN: llc -mtriple powerpc64-ibm-aix-xcoff < %s | FileCheck %s
 
 @llvm.global_ctors = appending global [1 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 65535, ptr @foo, ptr null }]
 
 define internal void @foo() {
   ret void
 }
 
-; FIXME: Adjust the comment after we use source file full path to generate unique
-; module id instead.
-; Use the Pid and timestamp to generate a unique module id when strong external
+; Use the Pid, threadId, and timestamp to generate a unique module id when strong external
 ; symbols are not available in current module. The module id generated in this
 ; way is not reproducible. A function name sample would be:
-; __sinit80000000_clangPidTime_119189_1597348415_0
+; __sinit80000000_clangPidTidTime_56689326_1_57027228417827568_0
 
 ; CHECK:              .lglobl        foo[DS]
 ; CHECK:              .lglobl        .foo
 ; CHECK:              .csect foo[DS]
-; CHECK-NEXT: __sinit80000000_clangPidTime_[[PID:[0-9]+]]_[[TIMESTAMP:[0-9]+]]_0:
+; CHECK-NEXT: __sinit80000000_clangPidTidTime_[[PID:[0-9]+]]_[[TID:[0-9]+]]_[[TIMESTAMP:[0-9]+]]_0:
 ; CHECK:      .foo:
-; CHECK-NEXT: .__sinit80000000_clangPidTime_[[PID]]_[[TIMESTAMP]]_0:
-; CHECK:      .globl  __sinit80000000_clangPidTime_[[PID]]_[[TIMESTAMP]]_0
-; CHECK:      .globl  .__sinit80000000_clangPidTime_[[PID]]_[[TIMESTAMP]]_0
+; CHECK-NEXT: .__sinit80000000_clangPidTidTime_[[PID]]_[[TID]]_[[TIMESTAMP]]_0:
+; CHECK:      .globl  __sinit80000000_clangPidTidTime_[[PID]]_[[TID]]_[[TIMESTAMP]]_0
+; CHECK:      .globl  .__sinit80000000_clangPidTidTime_[[PID]]_[[TID]]_[[TIMESTAMP]]_0