[Local][InstCombine] Handle MD_noundef in combineMetadataCSE

[nikic]

LGTM

llvm/lib/Transforms/Utils/Local.cpp

void llvm::combineMetadataForCSE(Instruction *K, const Instruction *J,
   unsigned KnownIDs[] = {
       LLVMContext::MD_tbaa,            LLVMContext::MD_alias_scope,
       LLVMContext::MD_noalias,         LLVMContext::MD_range,
       LLVMContext::MD_invariant_load,  LLVMContext::MD_nonnull,
       LLVMContext::MD_invariant_group, LLVMContext::MD_align,
       LLVMContext::MD_dereferenceable,
       LLVMContext::MD_dereferenceable_or_null,
       LLVMContext::MD_access_group,    LLVMContext::MD_preserve_access_index,
-      LLVMContext::MD_nontemporal};
+      LLVMContext::MD_nontemporal,     LLVMContext::MD_noundef};
   combineMetadata(K, J, KnownIDs, KDominatesJ);
 }
 
 void llvm::copyMetadataForLoad(LoadInst &Dest, const LoadInst &Source) {
   SmallVector<std::pair<unsigned, MDNode *>, 8> MD;
   Source.getAllMetadata(MD);
   MDBuilder MDB(Dest.getContext());
   Type *NewType = Dest.getType();

llvm/test/Transforms/InstCombine/load-combine-metadata.ll

 ; RUN: opt -passes=instcombine -S < %s | FileCheck %s
 
 target datalayout = "e-m:e-p:64:64:64-i64:64-f80:128-n8:16:32:64-S128"
 
 ; CHECK-LABEL: @test_load_load_combine_metadata(
 ; Check that range and AA metadata is combined
 ; CHECK: %[[V:.*]] = load i32, ptr %0
 ; CHECK-SAME: !tbaa !{{[0-9]+}}
 ; CHECK-SAME: !range ![[RANGE:[0-9]+]]
+; CHECK-SAME: !noundef !{{[0-9]+}}
 ; CHECK: store i32 %[[V]], ptr %1
 ; CHECK: store i32 %[[V]], ptr %2
 define void @test_load_load_combine_metadata(ptr, ptr, ptr) {
-  %a = load i32, ptr %0, !tbaa !8, !range !0, !alias.scope !5, !noalias !6
-  %b = load i32, ptr %0, !tbaa !8, !range !1
+  %a = load i32, ptr %0, !tbaa !8, !range !0, !noundef !10, !alias.scope !5, !noalias !6
+  %b = load i32, ptr %0, !tbaa !8, !range !1, !noundef !10
   store i32 %a, ptr %1
   store i32 %b, ptr %2
   ret void
 }
 
 ; CHECK: ![[RANGE]] = !{i32 0, i32 5}
 !0 = !{ i32 0, i32 5 }
 !1 = !{ i32 7, i32 9 }
 !2 = !{!2}
 !3 = !{!3, !2}
 !4 = !{!4, !2}
 !5 = !{!3}
 !6 = !{!4}
 !7 = !{ !"tbaa root" }
 !8 = !{ !9, !9, i64 0 }
 !9 = !{ !"scalar type", !7}
+!10 = !{}