perf(build): don't check the compiler's flags for every target
The TF_FLAGS variable must be recursively expanded as the rules that use
it are defined before it has been fully defined. That has the
unfortunate side effect of spawning a subshell that calls the compiler
for every file that is being built, thrashing multicore build times.
We don't cater to the possibility of the toolchain changing mid build so
precomputing this value would be more sensible. Doing a clean build on
an Intel dual socket Xeon Gold 5218 (i.e. 64 threads) workstation used
to take about 9 seconds. After this patch it takes about 1.5. Single
core performance went from ~45 seconds to about 25.
Change-Id: If56ed0ab3cc42bc482d9dd05a41ffbff4dd7f147
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
2 files changed