[llvm-exegesis] Make SubprocessMemoryTest use PIDs (#65245)

This patch makes SubprocessMemoryTest use process PIDs during creation
of the SubprocessMemory objects within the tests so that there isn't
interference between multiple instances of the test running at the same
time which could potentially occur in multi-user environments.

This is a continuation the review in https://reviews.llvm.org/D154680.

Author: boomanaiden154

llvm/unittests/tools/llvm-exegesis/X86/SubprocessMemoryTest.cpp

@@ -10,26 +10,47 @@
 
 #include "X86/TestBase.h"
 #include "gtest/gtest.h"
+#include <string>
 #include <unordered_map>
 
 #ifdef __linux__
 #include <endian.h>
 #include <fcntl.h>
 #include <sys/mman.h>
+#include <unistd.h>
 #endif // __linux__
 
+// This needs to be updated anytime a test is added or removed from the test
+// suite.
+static constexpr const size_t TestCount = 4;
+
 namespace llvm {
 namespace exegesis {
 
 #if defined(__linux__) && !defined(__ANDROID__)
 
 class SubprocessMemoryTest : public X86TestBase {
 protected:
+  int getSharedMemoryNumber(const unsigned TestNumber) {
+    // Do a process similar to 2D array indexing so that each process gets it's
+    // own shared memory space to avoid collisions. This will not overflow as
+    // the maximum value a PID can take on is 10^22.
+    return getpid() * TestCount + TestNumber;
+  }
+
   void
   testCommon(std::unordered_map<std::string, MemoryValue> MemoryDefinitions,
-             const int MainProcessPID) {
-    EXPECT_FALSE(SM.initializeSubprocessMemory(MainProcessPID));
-    EXPECT_FALSE(SM.addMemoryDefinition(MemoryDefinitions, MainProcessPID));
+             const unsigned TestNumber) {
+    EXPECT_FALSE(
+        SM.initializeSubprocessMemory(getSharedMemoryNumber(TestNumber)));
+    EXPECT_FALSE(SM.addMemoryDefinition(MemoryDefinitions,
+                                        getSharedMemoryNumber(TestNumber)));
+  }
+
+  std::string getSharedMemoryName(const unsigned TestNumber,
+                                  const unsigned DefinitionNumber) {
+    return "/" + std::to_string(getSharedMemoryNumber(TestNumber)) + "memdef" +
+           std::to_string(DefinitionNumber);
   }
 
   void checkSharedMemoryDefinition(const std::string &DefinitionName,
@@ -59,7 +80,7 @@ TEST_F(SubprocessMemoryTest, DISABLED_OneDefinition) {
 TEST_F(SubprocessMemoryTest, OneDefinition) {
 #endif
   testCommon({{"test1", {APInt(8, 0xff), 4096, 0}}}, 0);
-  checkSharedMemoryDefinition("/0memdef0", 4096, {0xff});
+  checkSharedMemoryDefinition(getSharedMemoryName(0, 0), 4096, {0xff});
 }
 
 #if defined(__powerpc__) || defined(__s390x__)
@@ -71,9 +92,9 @@ TEST_F(SubprocessMemoryTest, MultipleDefinitions) {
               {"test2", {APInt(8, 0xbb), 4096, 1}},
               {"test3", {APInt(8, 0xcc), 4096, 2}}},
              1);
-  checkSharedMemoryDefinition("/1memdef0", 4096, {0xaa});
-  checkSharedMemoryDefinition("/1memdef1", 4096, {0xbb});
-  checkSharedMemoryDefinition("/1memdef2", 4096, {0xcc});
+  checkSharedMemoryDefinition(getSharedMemoryName(1, 0), 4096, {0xaa});
+  checkSharedMemoryDefinition(getSharedMemoryName(1, 1), 4096, {0xbb});
+  checkSharedMemoryDefinition(getSharedMemoryName(1, 2), 4096, {0xcc});
 }
 
 #if defined(__powerpc__) || defined(__s390x__)
@@ -88,9 +109,9 @@ TEST_F(SubprocessMemoryTest, DefinitionFillsCompletely) {
   std::vector<uint8_t> Test1Expected(512, 0xaa);
   std::vector<uint8_t> Test2Expected(512, 0xbb);
   std::vector<uint8_t> Test3Expected(512, 0xcc);
-  checkSharedMemoryDefinition("/2memdef0", 4096, Test1Expected);
-  checkSharedMemoryDefinition("/2memdef1", 4096, Test2Expected);
-  checkSharedMemoryDefinition("/2memdef2", 4096, Test3Expected);
+  checkSharedMemoryDefinition(getSharedMemoryName(2, 0), 4096, Test1Expected);
+  checkSharedMemoryDefinition(getSharedMemoryName(2, 1), 4096, Test2Expected);
+  checkSharedMemoryDefinition(getSharedMemoryName(2, 2), 4096, Test3Expected);
 }
 
 // The following test is only supported on little endian systems.
@@ -123,7 +144,7 @@ TEST_F(SubprocessMemoryTest, DefinitionEndTruncation) {
       Test1Expected[I] = 0xaa;
     }
   }
-  checkSharedMemoryDefinition("/3memdef0", 4096, Test1Expected);
+  checkSharedMemoryDefinition(getSharedMemoryName(3, 0), 4096, Test1Expected);
 }
 
 #endif // defined(__linux__) && !defined(__ANDROID__)