Reland "[llvm-exegesis] Add in snippet address annotation (#74218)"

This reverts commit 30d700117b772d94d8474ec56bd6f9cc423fc613.

This relands commit 3ab41f912a6c219a93b87c257139822ea07c8863.

When I was updating the patch to use llvm::to_integer, I only ran the
lit tests and didn't run the unit tests, one of which started to fail.
This patch fixes the broken unit test.

1 files changed, 10 insertions, 2 deletions

diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
index dd7c1a3..d1b0a58 100644
--- a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
@@ -416,9 +416,17 @@ private:
 #endif // GLIBC_INITS_RSEQ
 
     size_t FunctionDataCopySize = this->Function.FunctionBytes.size();
+    void *MapAddress = NULL;
+    int MapFlags = MAP_PRIVATE | MAP_ANONYMOUS;
+
+    if (Key.SnippetAddress != 0) {
+      MapAddress = reinterpret_cast<void *>(Key.SnippetAddress);
+      MapFlags |= MAP_FIXED_NOREPLACE;
+    }
+
     char *FunctionDataCopy =
-        (char *)mmap(NULL, FunctionDataCopySize, PROT_READ | PROT_WRITE,
-                     MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
+        (char *)mmap(MapAddress, FunctionDataCopySize, PROT_READ | PROT_WRITE,
+                     MapFlags, 0, 0);
     if ((intptr_t)FunctionDataCopy == -1)
       exit(ChildProcessExitCodeE::FunctionDataMappingFailed);