scripts/falcon_fpr_ct_check.py compiles the integer fpr emulation with
gcc and clang for Cortex-M0+, M3, M7 and M33, RV32 and RV64, i386,
x86_64, AArch64, ESP32 and ESP32-S3 at -Os and -O2, and reports any
conditional branch outside the fixed-count loops of fpr_div and
fpr_sqrt and any compiler runtime call other than the 64-bit multiply.
A second pass compiles all of falcon.c with -g for the default and
smallest memory signers at -Os, -O2 and -O3, and reports any branch the
line table attributes to the fpr block: inlining into the FFT, sampler
and key generation code can undo what the block shows on its own. Stub
libc headers stand in for a sysroot.
It is meant for local runs after changes to the fpr code. A missing
toolchain is an error unless --allow-missing is given, and the cross
compilers can be named with ARM_GCC, RV_GCC, A64_GCC, XT_GCC and
XT3_GCC. Against master it fails with clang on Cortex-M0, RISC-V and
i386 and with gcc on ESP32, and the second pass fails on x86_64 when
the barriers are dropped there.
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