freebsd-dev/sys/conf/kern.mk
Warner Losh 647a9d043b Remove check for clang and expand the comment. Newer versions of gcc
generate dwarf4 by default as well, so always force dwarf2 when
generating debugging data. It is harmless on older versions of both
clang and gcc, but required on newer ones.
2014-04-01 14:24:20 +00:00

176 lines
5.6 KiB
Makefile

# $FreeBSD$
# Compat
MK_FORMAT_EXTENSIONS?=no
#
# Warning flags for compiling the kernel and components of the kernel:
#
CWARNFLAGS?= -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
-Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual \
-Wundef -Wno-pointer-sign ${FORMAT_EXTENSIONS} \
-Wmissing-include-dirs -fdiagnostics-show-option \
${CWARNEXTRA}
#
# The following flags are next up for working on:
# -Wextra
# Disable a few warnings for clang, since there are several places in the
# kernel where fixing them is more trouble than it is worth, or where there is
# a false positive.
.if ${COMPILER_TYPE} == "clang"
NO_WCONSTANT_CONVERSION= -Wno-constant-conversion
NO_WARRAY_BOUNDS= -Wno-array-bounds
NO_WSHIFT_COUNT_NEGATIVE= -Wno-shift-count-negative
NO_WSHIFT_COUNT_OVERFLOW= -Wno-shift-count-overflow
NO_WUNUSED_VALUE= -Wno-unused-value
NO_WSELF_ASSIGN= -Wno-self-assign
NO_WFORMAT_SECURITY= -Wno-format-security
NO_WUNNEEDED_INTERNAL_DECL= -Wno-unneeded-internal-declaration
NO_WSOMETIMES_UNINITIALIZED= -Wno-error-sometimes-uninitialized
# Several other warnings which might be useful in some cases, but not severe
# enough to error out the whole kernel build. Display them anyway, so there is
# some incentive to fix them eventually.
CWARNEXTRA?= -Wno-error-tautological-compare -Wno-error-empty-body \
-Wno-error-parentheses-equality -Wno-unused-function \
${NO_WFORMAT}
.endif
# External compilers may not support our format extensions. Allow them
# to be disabled. WARNING: format checking is disabled in this case.
.if ${MK_FORMAT_EXTENSIONS} == "no"
NO_WFORMAT= -Wno-format
.else
FORMAT_EXTENSIONS= -fformat-extensions
.endif
#
# On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
# and above adds code to the entry and exit point of every function to align the
# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
# per function call. While the 16-byte alignment may benefit micro benchmarks,
# it is probably an overall loss as it makes the code bigger (less efficient
# use of code cache tag lines) and uses more stack (less efficient use of data
# cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
# operations inside the kernel itself. These operations are exclusively
# reserved for user applications.
#
# gcc:
# Setting -mno-mmx implies -mno-3dnow
# Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
#
# clang:
# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
#
.if ${MACHINE_CPUARCH} == "i386"
.if ${COMPILER_TYPE} != "clang"
CFLAGS+= -mno-align-long-strings -mpreferred-stack-boundary=2
.else
CFLAGS+= -mno-aes -mno-avx
.endif
CFLAGS+= -mno-mmx -mno-sse -msoft-float
INLINE_LIMIT?= 8000
.endif
.if ${MACHINE_CPUARCH} == "arm"
INLINE_LIMIT?= 8000
.endif
#
# For IA-64, we use r13 for the kernel globals pointer and we only use
# a very small subset of float registers for integer divides.
#
.if ${MACHINE_CPUARCH} == "ia64"
CFLAGS+= -ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
INLINE_LIMIT?= 15000
.endif
#
# For sparc64 we want the medany code model so modules may be located
# anywhere in the 64-bit address space. We also tell GCC to use floating
# point emulation. This avoids using floating point registers for integer
# operations which it has a tendency to do.
#
.if ${MACHINE_CPUARCH} == "sparc64"
.if ${COMPILER_TYPE} == "clang"
CFLAGS+= -mcmodel=large -fno-dwarf2-cfi-asm
.else
CFLAGS+= -mcmodel=medany -msoft-float
.endif
INLINE_LIMIT?= 15000
.endif
#
# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
# operations inside the kernel itself. These operations are exclusively
# reserved for user applications.
#
# gcc:
# Setting -mno-mmx implies -mno-3dnow
# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
#
# clang:
# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
# (-mfpmath= is not supported)
#
.if ${MACHINE_CPUARCH} == "amd64"
.if ${COMPILER_TYPE} == "clang"
CFLAGS+= -mno-aes -mno-avx
.endif
CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
-fno-asynchronous-unwind-tables
INLINE_LIMIT?= 8000
.endif
#
# For PowerPC we tell gcc to use floating point emulation. This avoids using
# floating point registers for integer operations which it has a tendency to do.
# Also explicitly disable Altivec instructions inside the kernel.
#
.if ${MACHINE_CPUARCH} == "powerpc"
CFLAGS+= -msoft-float -mno-altivec
INLINE_LIMIT?= 15000
.endif
#
# Use dot symbols on powerpc64 to make ddb happy
#
.if ${MACHINE_ARCH} == "powerpc64"
CFLAGS+= -mcall-aixdesc
.endif
#
# For MIPS we also tell gcc to use floating point emulation
#
.if ${MACHINE_CPUARCH} == "mips"
CFLAGS+= -msoft-float
INLINE_LIMIT?= 8000
.endif
#
# GCC 3.0 and above like to do certain optimizations based on the
# assumption that the program is linked against libc. Stop this.
#
CFLAGS+= -ffreestanding
#
# GCC SSP support
#
.if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
CFLAGS+= -fstack-protector
.endif
#
# Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
# and gcc 4.8 is to generate DWARF version 4. However, our tools don't
# cope well with DWARF 4, so force it to genereate DWARF2, which they
# understand. Do this unconditionally as it is harmless when not needed,
# but critical for these newer versions.
#
.if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
CFLAGS+= -gdwarf-2
.endif