CodeGen: Clarify a comment about PGO in case statement ranges

llvm-svn: 199140

1 files changed, 4 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
index 79db4184868..880e801189a 100644
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -999,9 +999,10 @@ void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) {
     // Range is small enough to add multiple switch instruction cases.
     uint64_t Total = CaseCnt.getCount() - CaseCnt.getParentCount();
     unsigned NCases = Range.getZExtValue() + 1;
-    // Divide the weights evenly between the cases, ensuring that the total
-    // weight is preserved. Ie, a weight of 5 over three cases will be
-    // distributed as weights of 2, 2, and 1.
+    // We only have one region counter for the entire set of cases here, so we
+    // need to divide the weights evenly between the generated cases, ensuring
+    // that the total weight is preserved. Ie, a weight of 5 over three cases
+    // will be distributed as weights of 2, 2, and 1.
     uint64_t Weight = Total / NCases, Rem = Total % NCases;
     for (unsigned I = 0; I != NCases; ++I) {
       if (SwitchWeights)