PostgreSQLv14 TPC-H performance GCC vs Clang

Hi
PostgreSQLv14 source code build with GCCv11.2 and Clangv12(without JIT)
with optimisation flags like O3 and tested with HammerDB
Observed TPC-H , GCC performance better than Clang(without JIT). The
performance difference ~22% and also noticed the assembly code difference
GCC vs Clang( e.g. GCC inlined functionality compared to Clang).

Environment details:
————————-
OS :RHEL8.4
Bare metal : Apple/AMD EPYC/IBM
Test(TPC-H) Benchmark Environment:HammerDB

Is the performance difference mainly because of below points ?
1 data over flow and calculations like int128(int128.c) and C arithmetic
operations(functions include in float.h e.g float4_mul)

And please suggest is any another functionality or code points need to
check on the performance difference