[compiler-rt] [profile] Implement a non-mmap path when reading profile files from a non-local filesystem (PR #131177)

[Hubert Tong via llvm-commits]

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@@ -16,17 +20,23 @@ __attribute__((noinline)) void func1() {}
 __attribute__((noinline)) void func2() {}
 
 int main(void) {
-  //                       child     | parent
-  int status;         // func1 func2 | func1 func2
-  func1();            //   +1        |   +1        (*)
-  pid_t pid = fork(); //             |
-  if (pid == -1)      //             |
-    return 1;         //             |
-  if (pid == 0)       //             |
-    func2();          //         +1  |
-  func1();            //   +1        |   +1
-  if (pid)            // ------------+------------
-    wait(&status);    //    2     1  |    2    0
-  return 0;           // (*)  the child inherits counter values prior to fork
-                      //      from the parent in non-continuous mode.
+  //                           child     | parent
+  //                         func1 func2 | func1 func2
+  func1();              //   +10       |   +1        (*)
+  int i = 10;           //             |
+  while (i-- > 0) {     //             |
+    pid_t pid = fork(); //             |
+    if (pid == -1)      //             |
+      return 1;         //             |
+    if (pid == 0) {     //             |
+      func2();          //         +10 |
+      func1();          //   +10       |
+      return 0;         //             |
+    }                   //             |
+  }                     // ------------+------------
+  int status;           //   20     10 |   1     0
+  i = 10;
+  while (i-- > 0)
+    wait(&status);      // (*)  the child inherits counter values prior to fork
+  return 0;             //      from the parent in non-continuous mode.
----------------
hubert-reinterpretcast wrote:

My bad for splitting the comment block in my previous suggestion.
```suggestion
  i = 10;               // (*)  the child inherits counter values prior to fork
  while (i-- > 0)       //      from the parent in non-continuous mode.
    wait(&status);
  return 0;
```

https://github.com/llvm/llvm-project/pull/131177