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| author | David Lechner <david@pybricks.com> | 2022-12-18 18:26:32 -0600 |
|---|---|---|
| committer | Damien George <damien@micropython.org> | 2024-02-05 14:04:15 +1100 |
| commit | 23342eff906a99fc0a006916d350c86426fd9204 (patch) | |
| tree | 1a9c76bc851ff6f9b22a9923d2d3e054720963e5 | |
| parent | ac8e7f7b67ea13e7e9f816d3cfd4ddae4782db8d (diff) | |
| download | micropython-23342eff906a99fc0a006916d350c86426fd9204.tar.gz micropython-23342eff906a99fc0a006916d350c86426fd9204.zip | |
windows/Makefile: Fix float exact int formatting on 32-bit mingw.
When compiler optimizations are enabled on the mingw version of gcc, we are
getting failing tests because of rounding issues, for example:
print(float("1e24"))
would print
9.999999999999999e+23
instead of
1e+24
It turns out special compiler options are needed to get GCC to use the SSE
instruction set instead of the 387 coprocessor (which uses 80-bit precision
internall).
Signed-off-by: David Lechner <david@pybricks.com>
| -rw-r--r-- | ports/windows/Makefile | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/ports/windows/Makefile b/ports/windows/Makefile index 94bd3f99f9..bb635167da 100644 --- a/ports/windows/Makefile +++ b/ports/windows/Makefile @@ -86,6 +86,15 @@ ifneq ($(FROZEN_MANIFEST),) CFLAGS += -DMPZ_DIG_SIZE=16 endif +ifeq ($(shell $(CC) -dumpmachine),i686-w64-mingw32) +# GCC disables the SSE instruction set by default on i366 targets and we have +# to specify all three of these options to enable it. +# https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html (see -mfpmath=unit section) +# Enabling the SSE instruction set is necessary to get correct rounding of floating points. +# https://lemire.me/blog/2020/06/26/gcc-not-nearest +CFLAGS += -msse -mfpmath=sse -march=pentium4 +endif + CXXFLAGS += $(filter-out -std=gnu99,$(CFLAGS)) include $(TOP)/py/mkrules.mk |