[llvm] [llvm-profgen] Set FirstLoadableAddress only once (PR #151257)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-pgo

Author: Wei Wang (apolloww)

<details>
<summary>Changes</summary>

The address of the first loadable segment can be zero, so `FirstLoadableAddress` may actually point to the second loadable segment. Use an optional instead. 

---
Full diff: https://github.com/llvm/llvm-project/pull/151257.diff


1 Files Affected:

- (modified) llvm/tools/llvm-profgen/ProfiledBinary.h (+5-2) 


``````````diff
diff --git a/llvm/tools/llvm-profgen/ProfiledBinary.h b/llvm/tools/llvm-profgen/ProfiledBinary.h
index 0588cb48b2af6..8bc7e7b3b0061 100644
--- a/llvm/tools/llvm-profgen/ProfiledBinary.h
+++ b/llvm/tools/llvm-profgen/ProfiledBinary.h
@@ -199,7 +199,7 @@ class ProfiledBinary {
   // The runtime base address that the first executable segment is loaded at.
   uint64_t BaseAddress = 0;
   // The runtime base address that the first loadabe segment is loaded at.
-  uint64_t FirstLoadableAddress = 0;
+  std::optional<uint64_t> FirstLoadableAddress;
   // The preferred load address of each executable segment.
   std::vector<uint64_t> PreferredTextSegmentAddresses;
   // The file offset of each executable segment.
@@ -381,7 +381,10 @@ class ProfiledBinary {
     return PreferredTextSegmentAddresses[0];
   }
   // Return the preferred load address for the first loadable segment.
-  uint64_t getFirstLoadableAddress() const { return FirstLoadableAddress; }
+  uint64_t getFirstLoadableAddress() const {
+    assert(FirstLoadableAddress && "FirstLoadableAddress must be set.");
+    return *FirstLoadableAddress;
+  }
   // Return the file offset for the first executable segment.
   uint64_t getTextSegmentOffset() const { return TextSegmentOffsets[0]; }
   const std::vector<uint64_t> &getPreferredTextSegmentAddresses() const {

``````````

</details>


https://github.com/llvm/llvm-project/pull/151257