[PATCH] D26581: Make WholeProgramDevirt understand ConstStruct vtables.

[Peter Collingbourne via Phabricator via llvm-commits]

pcc added inline comments.


================
Comment at: lib/Transforms/IPO/WholeProgramDevirt.cpp:386
 
+Optional<unsigned>
+DevirtModule::getOpAtOffset(const Constant *I, const uint64_t Offset) {
----------------
Could be simpler to return a `const Constant *` from this function.


================
Comment at: lib/Transforms/IPO/WholeProgramDevirt.cpp:428-429
 
-    auto Init = dyn_cast<ConstantArray>(TM.Bits->GV->getInitializer());
-    if (!Init)
-      return false;
-    ArrayType *VTableTy = Init->getType();
-
-    uint64_t ElemSize =
-        M.getDataLayout().getTypeAllocSize(VTableTy->getElementType());
-    uint64_t GlobalSlotOffset = TM.Offset + ByteOffset;
-    if (GlobalSlotOffset % ElemSize != 0)
-      return false;
+    const Constant *I = TM.Bits->GV->getInitializer();
+    const uint64_t GlobalSlotOffset = TM.Offset + ByteOffset;
+    Optional<unsigned> Op = getOpAtOffset(I, GlobalSlotOffset);
----------------
These two could be folded into the only use (after applying my suggestion above).


================
Comment at: test/Transforms/WholeProgramDevirt/non-array-vtable.ll:1
 ; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
 
----------------
struct-vtable.ll would be a better name for this test.


https://reviews.llvm.org/D26581