[GVN] Preserve !range metadata when PRE'ing loads

[• dberlin]

LGTM

[• dberlin]

(as an aside, having to copy every type of metadata separately everywhere
seems ... bad, i'm kind of surprised we can't just say "transfer metadata
of these from this instruction to this one" at a minimum as a utility
function)))

lib/Transforms/Scalar/GVN.cpp

for (const auto &PredLoad : PredLoads) {
     LI->getAAMetadata(Tags);
     if (Tags)
       NewLoad->setAAMetadata(Tags);
 
     if (auto *MD = LI->getMetadata(LLVMContext::MD_invariant_load))
       NewLoad->setMetadata(LLVMContext::MD_invariant_load, MD);
     if (auto *InvGroupMD = LI->getMetadata(LLVMContext::MD_invariant_group))
       NewLoad->setMetadata(LLVMContext::MD_invariant_group, InvGroupMD);
+    if (auto *RangeMD = LI->getMetadata(LLVMContext::MD_range))
+      NewLoad->setMetadata(LLVMContext::MD_range, RangeMD);
 
     // Transfer DebugLoc.
     NewLoad->setDebugLoc(LI->getDebugLoc());
 
     // Add the newly created load.
     ValuesPerBlock.push_back(AvailableValueInBlock::get(UnavailablePred,
                                                         NewLoad));
     MD->invalidateCachedPointerInfo(LoadPtr);

test/Transforms/GVN/load-metadata.ll

+; RUN: opt -S -gvn < %s | FileCheck %s
+
+define i32 @test1(i32* %p, i1 %C) {
+; CHECK-LABEL: @test1(
+block1:
+  br i1 %C, label %block2, label %block3
+
+block2:
+ br label %block4
+; CHECK: block2:
+; CHECK-NEXT: load i32, i32* %p, !range !0, !invariant.group !1
+
+block3:
+  store i32 0, i32* %p
+  br label %block4
+
+block4:
+  %PRE = load i32, i32* %p, !range !0, !invariant.group !1
+  ret i32 %PRE
+}
+
+
+!0 = !{i32 40, i32 100}
+!1 = !{!"magic ptr"}