[llvm] fb19aa0 - [CSSPGO][llvm-profgen] Fix an issue in findDisjointRanges

[Hongtao Yu via llvm-commits]

Author: Hongtao Yu
Date: 2021-06-18T14:38:48-07:00
New Revision: fb19aa0c74fdb864ddbd677a7b3585661966a098

URL: https://github.com/llvm/llvm-project/commit/fb19aa0c74fdb864ddbd677a7b3585661966a098
DIFF: https://github.com/llvm/llvm-project/commit/fb19aa0c74fdb864ddbd677a7b3585661966a098.diff

LOG: [CSSPGO][llvm-profgen] Fix an issue in findDisjointRanges

We were using 0 as an indicator of invalid offset when computing disjoint ranges. In reality, 0 can be an valid code offset which stands for the first function in .text section. I'm using UINT64_MAX as an invalid code offset instead.

Reviewed By: wenlei

Differential Revision: https://reviews.llvm.org/D104497

Added: 
    

Modified: 
    llvm/tools/llvm-profgen/ProfileGenerator.cpp

Removed: 
    


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diff  --git a/llvm/tools/llvm-profgen/ProfileGenerator.cpp b/llvm/tools/llvm-profgen/ProfileGenerator.cpp
index 5c96ca938e61..e0a31937dcbe 100644
--- a/llvm/tools/llvm-profgen/ProfileGenerator.cpp
+++ b/llvm/tools/llvm-profgen/ProfileGenerator.cpp
@@ -179,19 +179,20 @@ void ProfileGenerator::findDisjointRanges(RangeSample &DisjointRanges,
     Boundaries[End].addEndCount(Count);
   }
 
-  uint64_t BeginAddress = 0;
+  uint64_t BeginAddress = UINT64_MAX;
   int Count = 0;
   for (auto Item : Boundaries) {
     uint64_t Address = Item.first;
     BoundaryPoint &Point = Item.second;
     if (Point.BeginCount) {
-      if (BeginAddress)
+      if (BeginAddress != UINT64_MAX)
         DisjointRanges[{BeginAddress, Address - 1}] = Count;
       Count += Point.BeginCount;
       BeginAddress = Address;
     }
     if (Point.EndCount) {
-      assert(BeginAddress && "First boundary point cannot be 'end' point");
+      assert((BeginAddress != UINT64_MAX) &&
+             "First boundary point cannot be 'end' point");
       DisjointRanges[{BeginAddress, Address}] = Count;
       Count -= Point.EndCount;
       BeginAddress = Address + 1;