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bpo-30104: Use -fno-strict-aliasing on clang (#1221) 

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.

LLVM bug report:
https://bugs.llvm.org//show_bug.cgi?id=31928
This commit is contained in:
Victor Stinner 2017-04-21 11:24:34 +02:00 committed by GitHub
parent 791dc83119
commit 28205b203a
2 changed files with 32 additions and 12 deletions
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20
configure vendored
View File

@ -6814,7 +6814,14 @@ then
# Clang also needs -fwrapv # Clang also needs -fwrapv
case $CC in case $CC in
*clang*) WRAP="-fwrapv" *clang*)
WRAP="-fwrapv"
# bpo-30104: Python/dtoa.c requires to be build with
# -fno-strict-aliasing to fix compiler issue on the
# double/ULong[2] union using clang 4.0 and optimization level
# -O2 or higher
# https://bugs.llvm.org//show_bug.cgi?id=31928
ALIASING="-fno-strict-aliasing"
;; ;;
esac esac
@ -6824,18 +6831,21 @@ then
# Optimization messes up debuggers, so turn it off for # Optimization messes up debuggers, so turn it off for
# debug builds. # debug builds.
if "$CC" -v --help 2>/dev/null |grep -- -Og > /dev/null; then if "$CC" -v --help 2>/dev/null |grep -- -Og > /dev/null; then
OPT="-g -Og -Wall $STRICT_PROTO" OPT="-g -Og -Wall"
else else
OPT="-g -O0 -Wall $STRICT_PROTO" OPT="-g -O0 -Wall"
fi fi
else else
OPT="-g $WRAP -O3 -Wall $STRICT_PROTO" OPT="-g $WRAP -O3 -Wall"
fi fi
;; ;;
*) *)
OPT="-O3 -Wall $STRICT_PROTO" OPT="-O3 -Wall"
;; ;;
esac esac
OPT="$OPT $STRICT_PROTO $ALIASING"
case $ac_sys_system in case $ac_sys_system in
SCO_SV*) OPT="$OPT -m486 -DSCO5" SCO_SV*) OPT="$OPT -m486 -DSCO5"
;; ;;

20
configure.ac
View File

@ -1454,7 +1454,14 @@ then
# Clang also needs -fwrapv # Clang also needs -fwrapv
case $CC in case $CC in
*clang*) WRAP="-fwrapv" *clang*)
WRAP="-fwrapv"
# bpo-30104: Python/dtoa.c requires to be build with
# -fno-strict-aliasing to fix compiler issue on the
# double/ULong[2] union using clang 4.0 and optimization level
# -O2 or higher
# https://bugs.llvm.org//show_bug.cgi?id=31928
ALIASING="-fno-strict-aliasing"
;; ;;
esac esac
@ -1464,18 +1471,21 @@ then
# Optimization messes up debuggers, so turn it off for # Optimization messes up debuggers, so turn it off for
# debug builds. # debug builds.
if "$CC" -v --help 2>/dev/null |grep -- -Og > /dev/null; then if "$CC" -v --help 2>/dev/null |grep -- -Og > /dev/null; then
OPT="-g -Og -Wall $STRICT_PROTO" OPT="-g -Og -Wall"
else else
OPT="-g -O0 -Wall $STRICT_PROTO" OPT="-g -O0 -Wall"
fi fi
else else
OPT="-g $WRAP -O3 -Wall $STRICT_PROTO" OPT="-g $WRAP -O3 -Wall"
fi fi
;; ;;
*) *)
OPT="-O3 -Wall $STRICT_PROTO" OPT="-O3 -Wall"
;; ;;
esac esac
OPT="$OPT $STRICT_PROTO $ALIASING"
case $ac_sys_system in case $ac_sys_system in
SCO_SV*) OPT="$OPT -m486 -DSCO5" SCO_SV*) OPT="$OPT -m486 -DSCO5"
;; ;;