[Attributor] Generalize heap to stack to any allocator with relevant properties

[reames]

Summary

This completes removal of the isXLike queries, and depends on a whole series of earlier patches.

[jdoerfert]

I'm going to assume the helpers do something sane. Works for me. Thx :)

[Bryce-MW]

LGTM

llvm/lib/Transforms/IPO/AttributorAttributes.cpp

 
 /// ----------------------- Heap-To-Stack Conversion ---------------------------
 struct AAHeapToStackFunction final : public AAHeapToStack {
 
   struct AllocationInfo {
     /// The call that allocates the memory.
     CallBase *const CB;
 
-    /// The kind of allocation.
-    const enum class AllocationKind {
-      MALLOC,
-      CALLOC,
-      ALIGNED_ALLOC,
-    } Kind;
-
     /// The library function id for the allocation.
     LibFunc LibraryFunctionId = NotLibFunc;
 
     /// The status wrt. a rewrite.
     enum {
       STACK_DUE_TO_USE,
       STACK_DUE_TO_FREE,
       INVALID,
void initialize(Attributor &A) override {
     auto AllocationIdentifierCB = [&](Instruction &I) {
       CallBase *CB = dyn_cast<CallBase>(&I);
       if (!CB)
         return true;
       if (isFreeCall(CB, TLI)) {
         DeallocationInfos[CB] = new (A.Allocator) DeallocationInfo{CB};
         return true;
       }
-      bool IsMalloc = isMallocLikeFn(CB, TLI);
-      bool IsAlignedAllocLike = !IsMalloc && isAlignedAllocLikeFn(CB, TLI);
-      bool IsCalloc =
-          !IsMalloc && !IsAlignedAllocLike && isCallocLikeFn(CB, TLI);
-      if (!IsMalloc && !IsAlignedAllocLike && !IsCalloc)
-        return true;
-      auto Kind =
-          IsMalloc ? AllocationInfo::AllocationKind::MALLOC
-                   : (IsCalloc ? AllocationInfo::AllocationKind::CALLOC
-                               : AllocationInfo::AllocationKind::ALIGNED_ALLOC);
-
-      AllocationInfo *AI = new (A.Allocator) AllocationInfo{CB, Kind};
+      // To do heap to stack, we need to know that the allocation itself is
+      // removable once uses are rewritten, and that we can initialize the
+      // alloca to the same pattern as the original allocation result.
+      if (isAllocationFn(CB, TLI) && isAllocRemovable(CB, TLI)) {
+        auto *I8Ty = Type::getInt8Ty(CB->getParent()->getContext());
+        if (nullptr != getInitialValueOfAllocation(CB, TLI, I8Ty)) {
+          AllocationInfo *AI = new (A.Allocator) AllocationInfo{CB};
           AllocationInfos[CB] = AI;
           TLI->getLibFunc(*CB, AI->LibraryFunctionId);
+        }
+      }
       return true;
     };
 
     bool UsedAssumedInformation = false;
     bool Success = A.checkForAllCallLikeInstructions(
         AllocationIdentifierCB, *this, UsedAssumedInformation,
         /* CheckBBLivenessOnly */ false,
         /* CheckPotentiallyDead */ true);