[InstCombine] Transform !range metadata to !nonnull when combining loads

[mehdi_amini]

Summary

When combining an integer load with !range metadata that does not include 0 to a pointer load, make sure emit !nonnull metadata on the newly-created pointer load. This prevents the !nonnull metadata from being dropped during a ptrtoint/inttoptr pair.

This fixes PR30597

[mehdi_amini]

You need to add llvm-commits as a subscriber from the beginning when submitting a patch on Phabricator.
Can you submit another one please? Sorry for the inconvenience.

Also it is helpful to upload patches with full context (git diff -U99999)

lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

       break;
     case LLVMContext::MD_range:
       // FIXME: It would be nice to propagate this in some way, but the type
-      // conversions make it hard. If the new type is a pointer, we could
-      // translate it to !nonnull metadata.
+      // conversions make it hard.
+
+      // If it's a pointer now and the range does not contain 0, make it !nonnull.
+      if (NewTy->isPointerTy() && N->getNumOperands() == 2) {
+       unsigned int BitWidth = IC.getDataLayout().getTypeSizeInBits(NewTy);
+       if (!getConstantRangeFromMetadata(*N).contains(APInt(BitWidth, 0))) {
+          MDNode *NN = MDNode::get(LI.getContext(), None);
+          NewLoad->setMetadata(LLVMContext::MD_nonnull, NN);
+        }
+      }
       break;
     }
   }

 bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
   assert(SI.isUnordered() &&
          "this code has not been auditted for volatile or ordered store case");
-  
   BasicBlock *StoreBB = SI.getParent();
 
   // Check to see if the successor block has exactly two incoming edges.  If

test/Transforms/InstCombine/PR30597.ll

+; RUN: opt < %s -instcombine -simplifycfg -S | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK-LABEL: @dot_ref_s
+; CHECK-NEXT: ret 42
+
+; Function Attrs: readonly uwtable
+define i32 @dot_ref_s(i32** noalias nocapture readonly dereferenceable(8)) {
+entry-block:
+  %loadedptr = load i32*, i32** %0, align 8, !nonnull !0
+  %ptrtoint = ptrtoint i32* %loadedptr to i64
+  %inttoptr = inttoptr i64 %ptrtoint to i32*
+  %switchtmp = icmp eq i32* %inttoptr, null
+  br i1 %switchtmp, label %bb6, label %bb7
+
+bb6:
+  ret i32 0
+
+bb7:
+  ret i32 42
+}
+
+!0 = !{}