[InstCombine] Preserve !annotation for newly created instructions.

When replacing an instruction with !annotation with a newly created
replacement, add the !annotation metadata to the replacement.

This mostly covers cases where the new instructions are created using
the ::Create helpers. Instructions created by IRBuilder will be handled
by D91444.

Reviewed By: thegameg

Differential Revision: https://reviews.llvm.org/D93399

Author: fhahn

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

@@ -3565,8 +3565,8 @@ bool InstCombiner::run() {
         LLVM_DEBUG(dbgs() << "IC: Old = " << *I << '\n'
                           << "    New = " << *Result << '\n');
 
-        if (I->getDebugLoc())
-          Result->setDebugLoc(I->getDebugLoc());
+        Result->copyMetadata(*I,
+                             {LLVMContext::MD_dbg, LLVMContext::MD_annotation});
         // Everything uses the new instruction now.
         I->replaceAllUsesWith(Result);
 

llvm/test/Transforms/InstCombine/annotations.ll

@@ -7,7 +7,7 @@
 ; instruction has !annotation metadata.
 define i1 @fold_to_new_instruction(i8* %a, i8* %b) {
 ; CHECK-LABEL: define {{.+}} @fold_to_new_instruction({{.+}}
-; CHECK-NEXT:    [[C:%.*]] = icmp uge i8* [[A:%.*]], [[B:%[a-z]*]]
+; CHECK-NEXT:    [[C:%.*]] = icmp uge i8* [[A:%.*]], [[B:%[a-z]*]], !annotation [[ANN:![0-9]+]]
 ; CHECK-NEXT:    ret i1 [[C]]
 ;
   %a.c = bitcast i8* %a to i32*, !annotation !0