mirror of https://github.com/torvalds/linux.git
dc5723b02e
This change adds build system support for Clang's Link Time Optimization (LTO). With -flto, instead of ELF object files, Clang produces LLVM bitcode, which is compiled into native code at link time, allowing the final binary to be optimized globally. For more details, see: https://llvm.org/docs/LinkTimeOptimization.html The Kconfig option CONFIG_LTO_CLANG is implemented as a choice, which defaults to LTO being disabled. To use LTO, the architecture must select ARCH_SUPPORTS_LTO_CLANG and support: - compiling with Clang, - compiling all assembly code with Clang's integrated assembler, - and linking with LLD. While using CONFIG_LTO_CLANG_FULL results in the best runtime performance, the compilation is not scalable in time or memory. CONFIG_LTO_CLANG_THIN enables ThinLTO, which allows parallel optimization and faster incremental builds. ThinLTO is used by default if the architecture also selects ARCH_SUPPORTS_LTO_CLANG_THIN: https://clang.llvm.org/docs/ThinLTO.html To enable LTO, LLVM tools must be used to handle bitcode files, by passing LLVM=1 and LLVM_IAS=1 options to make: $ make LLVM=1 LLVM_IAS=1 defconfig $ scripts/config -e LTO_CLANG_THIN $ make LLVM=1 LLVM_IAS=1 To prepare for LTO support with other compilers, common parts are gated behind the CONFIG_LTO option, and LTO can be disabled for specific files by filtering out CC_FLAGS_LTO. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20201211184633.3213045-3-samitolvanen@google.com |
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| .. | ||
| bitops | ||
| vdso | ||
| Kbuild | ||
| asm-offsets.h | ||
| asm-prototypes.h | ||
| atomic-instrumented.h | ||
| atomic-long.h | ||
| atomic.h | ||
| atomic64.h | ||
| audit_change_attr.h | ||
| audit_dir_write.h | ||
| audit_read.h | ||
| audit_signal.h | ||
| audit_write.h | ||
| barrier.h | ||
| bitops.h | ||
| bitsperlong.h | ||
| bug.h | ||
| bugs.h | ||
| cache.h | ||
| cacheflush.h | ||
| checksum.h | ||
| cmpxchg-local.h | ||
| cmpxchg.h | ||
| compat.h | ||
| current.h | ||
| delay.h | ||
| device.h | ||
| div64.h | ||
| dma-mapping.h | ||
| dma.h | ||
| early_ioremap.h | ||
| emergency-restart.h | ||
| error-injection.h | ||
| exec.h | ||
| export.h | ||
| extable.h | ||
| fb.h | ||
| fixmap.h | ||
| flat.h | ||
| ftrace.h | ||
| futex.h | ||
| getorder.h | ||
| gpio.h | ||
| hardirq.h | ||
| hugetlb.h | ||
| hw_irq.h | ||
| hyperv-tlfs.h | ||
| ide_iops.h | ||
| int-ll64.h | ||
| io.h | ||
| ioctl.h | ||
| iomap.h | ||
| irq.h | ||
| irq_regs.h | ||
| irq_work.h | ||
| irqflags.h | ||
| kdebug.h | ||
| kmap_size.h | ||
| kprobes.h | ||
| kvm_para.h | ||
| kvm_types.h | ||
| linkage.h | ||
| local.h | ||
| local64.h | ||
| mcs_spinlock.h | ||
| memory_model.h | ||
| mm-arch-hooks.h | ||
| mm_hooks.h | ||
| mmiowb.h | ||
| mmiowb_types.h | ||
| mmu.h | ||
| mmu_context.h | ||
| module.h | ||
| module.lds.h | ||
| mshyperv.h | ||
| msi.h | ||
| nommu_context.h | ||
| page.h | ||
| param.h | ||
| parport.h | ||
| pci.h | ||
| pci_iomap.h | ||
| percpu.h | ||
| pgalloc.h | ||
| pgtable-nop4d.h | ||
| pgtable-nopmd.h | ||
| pgtable-nopud.h | ||
| pgtable_uffd.h | ||
| preempt.h | ||
| qrwlock.h | ||
| qrwlock_types.h | ||
| qspinlock.h | ||
| qspinlock_types.h | ||
| resource.h | ||
| rwonce.h | ||
| seccomp.h | ||
| sections.h | ||
| serial.h | ||
| set_memory.h | ||
| shmparam.h | ||
| signal.h | ||
| simd.h | ||
| spinlock.h | ||
| statfs.h | ||
| string.h | ||
| switch_to.h | ||
| syscall.h | ||
| syscalls.h | ||
| termios-base.h | ||
| termios.h | ||
| timex.h | ||
| tlb.h | ||
| tlbflush.h | ||
| topology.h | ||
| trace_clock.h | ||
| uaccess.h | ||
| unaligned.h | ||
| user.h | ||
| vermagic.h | ||
| vga.h | ||
| vmlinux.lds.h | ||
| vtime.h | ||
| word-at-a-time.h | ||
| xor.h | ||