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configure: disable Apple clang size optimizations that hurt runtime speed #23080

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configure: disable Apple clang size optimizations that hurt runtime speed #23080

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12 changes: 12 additions & 0 deletions configure.ac
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Expand Up @@ -219,6 +219,18 @@ esac
dnl See https://github.com/php/php-src/issues/14140
AX_CHECK_COMPILE_FLAG([-ffp-contract=off], [CFLAGS="$CFLAGS -ffp-contract=off"])

dnl Apple clang enables the AArch64 machine outliner and hot/cold code
dnl splitting by default at -O2. Both trade speed for size: outlining
dnl inserts extra calls into hot paths (including the zval destructor
dnl loops) and cold-split fragments are compiled for size. Disabling them
dnl speeds up CPU-bound scripts measurably (~4% on a large static
dnl analysis workload). -Werror is needed because clang only warns about
dnl unknown -m flags.
AX_CHECK_COMPILE_FLAG([-mno-outline],
[CFLAGS="$CFLAGS -mno-outline"], [], [-Werror])
AX_CHECK_COMPILE_FLAG([-Xclang -fno-split-cold-code],
[CFLAGS="$CFLAGS -Xclang -fno-split-cold-code"], [], [-Werror])

dnl Mark symbols hidden by default if the compiler (for example, gcc >= 4)
dnl supports it. This can help reduce the binary size and startup time.
AX_CHECK_COMPILE_FLAG([-fvisibility=hidden],
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