[NFC] Add a test case to make sure EarlyCSE preserves !prof when one

instruction CSE'ed another.

- This should be a part of D148877. Before that patch, !prof is not added to known-id-set [1], and turns out unknown types of metadata are dropped in the implementation [2].
  - This test is mainly added to make sure there won't be regressions for this kind of pattern. The pattern is observed it in application code; looks like the result of indirect call is used as function arguments initially; after the function is inlined load-after-store CSE opportunity is exposed.

  [1] https://github.com/llvm/llvm-project/blob/f478721231bdb71ba8f0f6fb21673b9b7f652add/llvm/lib/Transforms/Utils/Local.cpp#L2727-L2741
  [2] https://github.com/llvm/llvm-project/blob/ade3c6a6a88ed3a9b06c076406f196da9d3cc1b9/llvm/lib/Transforms/Utils/Local.cpp#L2639

Differential Revision: https://reviews.llvm.org/D149396

llvm/test/Transforms/EarlyCSE/metadata.ll

@@ -0,0 +1,31 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
+; RUN: opt < %s -S -passes=early-cse | FileCheck %s
+
+; Test that when the load from %x is CSE'ed to %call1 by EarlyCSE, the !prof metadata
+; is not dropped.
+define i32 @indirect_call_value_profile_preserved(ptr %x, i32 %a, i32 %b, i32 %c)  {
+; CHECK-LABEL: define i32 @indirect_call_value_profile_preserved
+; CHECK-SAME: (ptr [[X:%.*]], i32 [[A:%.*]], i32 [[B:%.*]], i32 [[C:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CALL:%.*]] = tail call ptr @_Z10createTypei(i32 [[C]])
+; CHECK-NEXT:    [[VTABLE:%.*]] = load ptr, ptr [[CALL]], align 8
+; CHECK-NEXT:    [[VFN:%.*]] = getelementptr inbounds ptr, ptr [[VTABLE]], i64 1
+; CHECK-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[VFN]], align 8
+; CHECK-NEXT:    [[CALL1:%.*]] = tail call i32 [[TMP0]](ptr [[CALL]], i32 [[A]], i32 [[B]]), !prof [[PROF0:![0-9]+]]
+; CHECK-NEXT:    store i32 [[CALL1]], ptr [[X]], align 4
+; CHECK-NEXT:    ret i32 [[CALL1]]
+;
+entry:
+  %call = tail call ptr @_Z10createTypei(i32 %c)
+  %vtable = load ptr, ptr %call, align 8
+  %vfn = getelementptr inbounds ptr, ptr %vtable, i64 1
+  %0 = load ptr, ptr %vfn, align 8
+  %call1 = tail call i32 %0(ptr %call, i32 %a, i32 %b), !prof !0
+  store i32 %call1, ptr %x
+  %foo = load i32, ptr %x
+  ret i32 %foo
+}
+
+declare ptr @_Z10createTypei(i32)
+
+!0 =!{!"VP", i32 0, i64 1600, i64 12345, i64 1030, i64 678, i64 410}