Re: [UNIKRAFT PATCH v4 3/3] build: Add support for clang

[Razvan Deaconescu <razvan.deaconescu@xxxxxxxxx>]

All good.

Reviewed-by: Razvan Deaconescu <razvan.deaconescu@xxxxxxxxx>

Vlad-Andrei Badoiu <vlad_andrei.badoiu@xxxxxx> writes:
> We condition the gcc specific flags via have_gcc and the
> clang specific flags with have_clang.
>
> Signed-off-by: Alice Suiu <alicesuiu17@xxxxxxxxx>
> Signed-off-by: Vlad-Andrei Badoiu <vlad_andrei.badoiu@xxxxxx>
> ---
>  Makefile                    |  2 ++
>  Makefile.uk                 | 15 +++++++++++----
>  arch/x86/x86_64/Makefile.uk |  9 ++++++---
>  3 files changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index c22dbad..b12dc8b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -643,10 +643,12 @@ $(error You did not select a library that handles 
> bootstrapping! (e.g., ukboot))
>  endif
>  
>  ifeq ($(CONFIG_OPTIMIZE_LTO), y)
> +ifeq ($(call have_gcc),y)
>  ifneq ($(call gcc_version_ge,6,1),y)
>  $(error Your gcc version does not support incremental link time optimisation)
>  endif
>  endif
> +endif
>  
>  # Generate build rules
>  $(eval $(call 
> verbose_include,$(CONFIG_UK_BASE)/support/build/Makefile.build))
> diff --git a/Makefile.uk b/Makefile.uk
> index e505c04..9f0da22 100644
> --- a/Makefile.uk
> +++ b/Makefile.uk
> @@ -4,9 +4,11 @@
>  #
>  
> ################################################################################
>  
> -COMPFLAGS    += -nostdinc -nostdlib
> +COMPFLAGS    += -nostdlib
>  COMPFLAGS    += -U __linux__ -U __FreeBSD__ -U __sun__
> -COMPFLAGS    += -fno-omit-frame-pointer -fno-tree-sra -fno-split-stack
> +COMPFLAGS    += -fno-omit-frame-pointer
> +COMPFLAGS-$(call have_gcc)   += -fno-tree-sra -fno-split-stack -nostdinc
> +
>  ifneq ($(HAVE_STACKPROTECTOR),y)
>  COMPFLAGS    += -fno-stack-protector
>  endif
> @@ -19,12 +21,14 @@ CINCLUDES    += -I$(CONFIG_UK_BASE)/include
>  CXXINCLUDES  += -I$(CONFIG_UK_BASE)/include
>  GOCINCLUDES  += -I$(CONFIG_UK_BASE)/include
>  
> -LIBLDFLAGS  += -nostdinc -nostdlib -Wl,-r -Wl,-d -Wl,--build-id=none -no-pie
> +LIBLDFLAGS  += -nostdlib -Wl,-r -Wl,-d -Wl,--build-id=none -no-pie
> +LIBLDFLAGS-$(call have_gcc)  += -nostdinc
>  
>  # Set the text and data sections to be readable and writable. Also,
>  # do not page-align the data segment. If the output format supports
>  # Unix style magic numbers, mark the output as OMAGIC.
> -LDFLAGS     += -nostdinc -nostdlib -Wl,--omagic -Wl,--build-id=none
> +LDFLAGS      += -nostdlib -Wl,--omagic -Wl,--build-id=none
> +LDFLAGS-$(call have_gcc)     += -nostdinc
>  
>  COMPFLAGS-$(CONFIG_OPTIMIZE_NONE)         += -O0 -fno-optimize-sibling-calls 
> -fno-tree-vectorize
>  COMPFLAGS-$(CONFIG_OPTIMIZE_SIZE)         += -Os
> @@ -56,3 +60,6 @@ M4FLAGS      += -DUK_VERSION=$(UK_VERSION).$(UK_SUBVERSION)
>  # "--enable-default-pie" by default.
>  COMPFLAGS-$(call gcc_version_ge,6,1) += -fno-PIC
>  LDFLAGS-$(call gcc_version_ge,6,1)   += -no-pie
> +
> +COMPFLAGS-$(call have_clang) += -fno-builtin -fno-PIC
> +LDFLAGS-$(call have_clang)   += -no-pie
> diff --git a/arch/x86/x86_64/Makefile.uk b/arch/x86/x86_64/Makefile.uk
> index 24919fb..c4d5109 100644
> --- a/arch/x86/x86_64/Makefile.uk
> +++ b/arch/x86/x86_64/Makefile.uk
> @@ -1,7 +1,9 @@
>  ARCHFLAGS     += -D__X86_64__
> -ARCHFLAGS     += -m64 -mno-red-zone -fno-reorder-blocks 
> -fno-asynchronous-unwind-tables
> +ARCHFLAGS     += -m64 -mno-red-zone -fno-asynchronous-unwind-tables
> +ARCHFLAGS-$(call have_gcc)   += -fno-reorder-blocks
>  ISR_ARCHFLAGS += -D__X86_64__
> -ISR_ARCHFLAGS += -m64 -mno-red-zone -fno-reorder-blocks 
> -fno-asynchronous-unwind-tables
> +ISR_ARCHFLAGS += -m64 -mno-red-zone -fno-asynchronous-unwind-tables
> +ISR_ARCHFLAGS-$(call have_gcc)       += -fno-reorder-blocks
>  
>  CINCLUDES   += -I$(CONFIG_UK_BASE)/arch/x86/x86_64/include
>  ASINCLUDES  += -I$(CONFIG_UK_BASE)/arch/x86/x86_64/include
> @@ -9,7 +11,8 @@ CXXINCLUDES += -I$(CONFIG_UK_BASE)/arch/x86/x86_64/include
>  
>  # compiler flags to prevent use of extended (FP, SSE, AVX) registers.
>  # This is for files that contain trap/exception/interrupt handlers
> -ISR_ARCHFLAGS += -mno-80387 -mno-fp-ret-in-387 -mno-mmx -mno-sse -mno-avx
> +ISR_ARCHFLAGS += -mno-80387 -mno-mmx -mno-sse -mno-avx
> +ISR_ARCHFLAGS-$(call have_gcc)       += -mno-fp-ret-in-387
>  ISR_ARCHFLAGS-$(call gcc_version_ge,7,1) += -mgeneral-regs-only
>  
>  ARCHFLAGS-$(CONFIG_MARCH_X86_64_GENERIC)        += -mtune=generic