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

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.

Reviewed By: xingxue, daltenty

Differential Revision: https://reviews.llvm.org/D159319

Author: Wael Yehia

llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp

@@ -68,6 +68,7 @@
 #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"
@@ -2740,14 +2741,18 @@ bool PPCAIXAsmPrinter::doInitialization(Module &M) {
           // 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);

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

@@ -7,18 +7,16 @@ 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