[LazyValueInfo] Report nonnull range for nonnull pointers

[igor-laevsky]

Summary

Currently LazyValueInfo will report only alloca's as having nonnull range. For loads with !nonnull metadata it will bailout with no additional information. Same is true for calls returning nonnull pointers.

This change extends LazyValueInfo to handle this additional nonnull instructions.

[reames]

Nice cleanup. LGTM w/comment addressed.

lib/Analysis/LazyValueInfo.cpp

535

Please use a dyn_cast on the type to check the type since you have a cast below.

lib/Analysis/LazyValueInfo.cpp

bool LazyValueInfoCache::solveBlockValue(Value *Val, BasicBlock *BB) {
 
   if (PHINode *PN = dyn_cast<PHINode>(BBI)) {
     if (!solveBlockValuePHINode(Res, PN, BB))
       return false;
     insertResult(Val, BB, Res);
     return true;
   }
 
-  if (AllocaInst *AI = dyn_cast<AllocaInst>(BBI)) {
-    Res = LVILatticeVal::getNot(ConstantPointerNull::get(AI->getType()));
+  // If this value is a nonnull pointer, record it's range and bailout.
+  if (BBI->getType()->isPointerTy() &&
+      isKnownNonNull(BBI)) {
+    Res = LVILatticeVal::getNot(
+        ConstantPointerNull::get(cast<PointerType>(BBI->getType())));
     insertResult(Val, BB, Res);
     return true;
   }
 
   // We can only analyze the definitions of certain classes of instructions
   // (integral binops and casts at the moment), so bail if this isn't one.
   LVILatticeVal Result;
   if ((!isa<BinaryOperator>(BBI) && !isa<CastInst>(BBI)) ||

test/Transforms/CorrelatedValuePropagation/non-null.ll

null:
   br label %merge
 
 merge:
   %merged_arg = phi i8* [%another_arg, %null], [%arg1, %non_null]
   call void @test11_helper(i8* %merged_arg)
   ; CHECK: call void @test11_helper(i8* nonnull %merged_arg)
   ret void
 }
+
+declare void @test12_helper(i8* %arg)
+define void @test12(i8* %arg1, i8** %arg2) {
+; CHECK-LABEL: @test12
+entry:
+  %is_null = icmp eq i8* %arg1, null
+  br i1 %is_null, label %null, label %non_null
+
+non_null:
+  br label %merge
+
+null:
+  %another_arg = load i8*, i8** %arg2, !nonnull !{}
+  br label %merge
+
+merge:
+  %merged_arg = phi i8* [%another_arg, %null], [%arg1, %non_null]
+  call void @test12_helper(i8* %merged_arg)
+  ; CHECK: call void @test12_helper(i8* nonnull %merged_arg)
+  ret void
+}