edd1f930aa
section to stop gcc generating the dwarf2 .eh_frame unwind tables. It is dead weight for the time being. Maybe it can be used to perform stack traces and/or get the location of function arguments in ddb, but that requires a dwarf2 runtime interpreter, which we do not have. Approved by: re (amd64 "safe" bits)
70 lines
2.3 KiB
Makefile
70 lines
2.3 KiB
Makefile
# $FreeBSD$
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#
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# Warning flags for compiling the kernel and components of the kernel.
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#
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# Note that the newly added -Wcast-qual is responsible for generating
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# most of the remaining warnings. Warnings introduced with -Wall will
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# also pop up, but are easier to fix.
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CWARNFLAGS?= -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
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-Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual \
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-fformat-extensions -std=c99
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#
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# The following flags are next up for working on:
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# -W
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#
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# On the i386, do not align the stack to 16-byte boundaries. Otherwise GCC
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# 2.95 adds code to the entry and exit point of every function to align the
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# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
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# per function call. While the 16-byte alignment may benefit micro benchmarks,
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# it is probably an overall loss as it makes the code bigger (less efficient
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# use of code cache tag lines) and uses more stack (less efficient use of data
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# cache tag lines)
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#
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.if ${MACHINE_ARCH} == "i386"
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CFLAGS+= -mno-align-long-strings -mpreferred-stack-boundary=2
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.endif
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#
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# On the alpha, make sure that we don't use floating-point registers and
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# allow the use of BWX etc instructions (only needed for low-level i/o).
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# Also, reserve register t7 to point at per-cpu global variables.
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#
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.if ${MACHINE_ARCH} == "alpha"
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CFLAGS+= -mno-fp-regs -ffixed-8 -Wa,-mev6
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.endif
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#
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# For IA-64, we use r13 for the kernel globals pointer and we only use
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# a very small subset of float registers for integer divides.
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#
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.if ${MACHINE_ARCH} == "ia64"
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CFLAGS+= -ffixed-r13 -mfixed-range=f32-f127 -mno-sdata
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.endif
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#
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# For sparc64 we want medlow code model, and we tell gcc to use floating
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# point emulation. This avoids using floating point registers for integer
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# operations which it has a tendency to do.
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#
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.if ${MACHINE_ARCH} == "sparc64"
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CFLAGS+= -mcmodel=medlow -msoft-float
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.endif
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#
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# For AMD64, use a medium model for now. We'll switch to "kernel"
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# once pmap is ready. Be excessively careful to not generate FPU code.
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#
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.if ${MACHINE_ARCH} == "amd64"
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CFLAGS+= -mcmodel=kernel -mno-red-zone \
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-mfpmath=387 -mno-sse -mno-sse2 -mno-mmx -mno-3dnow \
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-msoft-float -fno-asynchronous-unwind-tables
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.endif
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#
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# GCC 3.0 and above like to do certain optimizations based on the
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# assumption that the program is linked against libc. Stop this.
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#
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CFLAGS+= -ffreestanding
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