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| author | Victor Stinner <victor.stinner@gmail.com> | 2017-05-02 08:47:37 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2017-05-02 08:47:37 (GMT) |
| commit | 809101f14f27ddb394cd77c477470761ecf99f41 (patch) | |
| tree | c72865d73dfa042b3aa4826ed4c33ace4dd5295e /Makefile.pre.in | |
| parent | 78b23ab6827410960577c01a33df8afc8fd4496e (diff) | |
| download | cpython-809101f14f27ddb394cd77c477470761ecf99f41.zip cpython-809101f14f27ddb394cd77c477470761ecf99f41.tar.gz cpython-809101f14f27ddb394cd77c477470761ecf99f41.tar.bz2 | |
bpo-30104: Use -fno-strict-aliasing on clang (#1376)
Python/dtoa.c is not compiled correctly with clang 4.0 and
optimization level -O2 or higher, because of an aliasing issue on the
double/ULong[2] union. Only compile dtoa.c with -fno-strict-aliasing.
LLVM bug report:
https://bugs.llvm.org//show_bug.cgi?id=31928
Diffstat (limited to 'Makefile.pre.in')
| -rw-r--r-- | Makefile.pre.in | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/Makefile.pre.in b/Makefile.pre.in index 8f27d73..3eef424 100644 --- a/Makefile.pre.in +++ b/Makefile.pre.in @@ -107,6 +107,8 @@ ARFLAGS= @ARFLAGS@ CFLAGSFORSHARED=@CFLAGSFORSHARED@ # C flags used for building the interpreter object files PY_CORE_CFLAGS= $(PY_CFLAGS) $(PY_CFLAGS_NODIST) $(PY_CPPFLAGS) $(CFLAGSFORSHARED) -DPy_BUILD_CORE +# Strict or non-strict aliasing flags used to compile dtoa.c, see above +CFLAGS_ALIASING=@CFLAGS_ALIASING@ # Machine-dependent subdirectories @@ -1535,6 +1537,13 @@ config.status: $(srcdir)/configure .c.o: $(CC) -c $(PY_CORE_CFLAGS) -o $@ $< +# bpo-30104: dtoa.c uses union to cast double to unsigned long[2]. clang 4.0 +# with -O2 or higher and strict aliasing miscompiles the ratio() function +# causing rounding issues. Compile dtoa.c using -fno-strict-aliasing on clang. +# https://bugs.llvm.org//show_bug.cgi?id=31928 +Python/dtoa.o: Python/dtoa.c + $(CC) -c $(PY_CORE_CFLAGS) $(CFLAGS_ALIASING) -o $@ $< + # Run reindent on the library reindent: ./$(BUILDPYTHON) $(srcdir)/Tools/scripts/reindent.py -r $(srcdir)/Lib |