add a fixme

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76324 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Utils/InlineCost.cpp b/lib/Transforms/Utils/InlineCost.cpp
index 5fe85e6ef29e29bfec9714bfffbf5de921e09eec..8925a752b19ae701218b0bacf306c0c11c288e45 100644 (file)
--- a/lib/Transforms/Utils/InlineCost.cpp
+++ b/lib/Transforms/Utils/InlineCost.cpp
@@ -45,6 +45,11 @@ unsigned InlineCostAnalyzer::FunctionInfo::
       
       // We can't constant propagate instructions which have effects or
       // read memory.
+      //
+      // FIXME: It would be nice to capture the fact that a load from a
+      // pointer-to-constant-global is actually a *really* good thing to zap.
+      // Unfortunately, we don't know the pointer that may get propagated here,
+      // so we can't make this decision.
       if (Inst.mayReadFromMemory() || Inst.mayHaveSideEffects() ||
           isa<AllocationInst>(Inst))
         continue;