functionality difference-performance postgreSQLv14-GCC-llvm-clang

Hi,

PostgreSQLv14- compiled with LLVM-Clangv13 and GCCv11,And captured
performance using HammerDBv4.3-TPC-H.
And Observed the functionality differences as LLVM-Clangv13-triggers
heapgetpage instead XidInMVCCSnapshot or vice versa with GCC.
I would like to know here the functionality differences triggered i.e.
function call "heapgetpage vs XidInMVCCSnapshot '' in GCC vs LLVM-Clangv13
And also observed the performance difference GCC performing (Query
execution time (small value is better) better than LLVM-Clang 13 on same
BareMetal with same H/W and DB configurations

perf data top hot functions:
LLVM-Clangv13:
=============
TPCH-Query-completed-50.526 seconds

Overhead Symbol
19.41% [.] tts_buffer_heap_getsomeattrs
* 17.75% [.] heapgetpage*
9.46% [.] bpchareq
5.86% [.] ExecEvalScalarArrayOp
5.85% [.] ExecInterpExpr
4.50% [.] ReadBuffer_common
3.02% [.] heap_getnextslot

GCCv11
=======

TPCH-Query-completed-41.593 seconds

21.13% [.] tts_buffer_heap_getsomeattrs
*11.58% [.] XidInMVCCSnapshot*
10.87% [.] bpchareq
7.07% [.] ExecEvalScalarArrayOp
5.93% [.] ExecInterpExpr
5.16% [.] ReadBuffer_common
3.61% [.] heapgetpage

Regards
Arjun