Tweak some comments.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56784 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/AddReadAttrs.cpp b/lib/Transforms/IPO/AddReadAttrs.cpp
index 3e7d860..b70bdaf 100644
--- a/lib/Transforms/IPO/AddReadAttrs.cpp
+++ b/lib/Transforms/IPO/AddReadAttrs.cpp
@@ -47,14 +47,14 @@
bool AddReadAttrs::runOnSCC(const std::vector<CallGraphNode *> &SCC) {
CallGraph &CG = getAnalysis<CallGraph>();
- // Check if any of the functions in the SCC read or write memory.
- // If they write memory then just give up.
+ // Check if any of the functions in the SCC read or write memory. If they
+ // write memory then they can't be marked readnone or readonly.
bool ReadsMemory = false;
for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
Function *F = SCC[i]->getFunction();
if (F == 0)
- // External node - may write memory.
+ // External node - may write memory. Just give up.
return false;
if (F->doesNotAccessMemory())
@@ -65,7 +65,7 @@
// something that writes memory, so treat them like declarations.
if (F->isDeclaration() || F->mayBeOverridden()) {
if (!F->onlyReadsMemory())
- // May write memory.
+ // May write memory. Just give up.
return false;
ReadsMemory = true;
@@ -83,7 +83,9 @@
continue;
if (II->mayWriteToMemory())
+ // Writes memory. Just give up.
return false;
+
ReadsMemory |= II->mayReadFromMemory();
}
}