[Xen-changelog] [xen-unstable] xen: add "clang=y" option to build Xen with clang/llvm instead of gcc.

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Tim Deegan <Tim.Deegan@xxxxxxxxxx>
# Date 1299496871 0
# Node ID d8ea33e7af7ee76ee3bea5411430ab876258ce78
# Parent  2bc9bd01b5fac6e42e3a6d56a7944f69b76972c1
xen: add "clang=y" option to build Xen with clang/llvm instead of gcc.

Tested with svn snapshot of clang and llvm from 17 February 2011.
Only x86_64 hypervisor builds (make dist-xen clang=y) are supported
and I haven't even begun to look at cross-compiling.

Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Acked-by: Keir Fraser <keir@xxxxxxx>
---


diff -r 2bc9bd01b5fa -r d8ea33e7af7e Config.mk
--- a/Config.mk Mon Mar 07 11:21:11 2011 +0000
+++ b/Config.mk Mon Mar 07 11:21:11 2011 +0000
@@ -148,6 +148,13 @@
 # result of any casted expression causes a warning.
 CFLAGS += -Wno-unused-value
 
+ifeq ($(clang),y)
+# Clang complains about macros that expand to 'if ( ( foo == bar ) ) ...'
+CFLAGS += -Wno-parentheses
+# And is over-zealous with the printf format lint
+CFLAGS += -Wno-format
+endif
+
 $(call cc-option-add,HOSTCFLAGS,HOSTCC,-Wdeclaration-after-statement)
 $(call cc-option-add,CFLAGS,CC,-Wdeclaration-after-statement)
 
diff -r 2bc9bd01b5fa -r d8ea33e7af7e config/StdGNU.mk
--- a/config/StdGNU.mk  Mon Mar 07 11:21:11 2011 +0000
+++ b/config/StdGNU.mk  Mon Mar 07 11:21:11 2011 +0000
@@ -1,6 +1,11 @@
 AS         = $(CROSS_COMPILE)as
+ifeq ($(clang),y)
+LD         = $(CROSS_COMPILE)gold
+CC         = $(CROSS_COMPILE)clang
+else
 LD         = $(CROSS_COMPILE)ld
 CC         = $(CROSS_COMPILE)gcc
+endif
 CPP        = $(CC) -E
 AR         = $(CROSS_COMPILE)ar
 RANLIB     = $(CROSS_COMPILE)ranlib
@@ -69,5 +74,8 @@
 CFLAGS += -O2 -fomit-frame-pointer
 else
 # Less than -O1 produces bad code and large stack frames
-CFLAGS += -O1 -fno-omit-frame-pointer -fno-optimize-sibling-calls
+CFLAGS += -O1 -fno-omit-frame-pointer
+ifneq ($(clang),y)
+CFLAGS += -fno-optimize-sibling-calls
 endif
+endif
diff -r 2bc9bd01b5fa -r d8ea33e7af7e xen/Makefile
--- a/xen/Makefile      Mon Mar 07 11:21:11 2011 +0000
+++ b/xen/Makefile      Mon Mar 07 11:21:11 2011 +0000
@@ -88,7 +88,7 @@
            -e 's/@@whoami@@/$(XEN_WHOAMI)/g' \
            -e 's/@@domain@@/$(XEN_DOMAIN)/g' \
            -e 's/@@hostname@@/$(shell hostname)/g' \
-           -e 's!@@compiler@@!$(shell $(CC) $(CFLAGS) -v 2>&1 | tail -1)!g' \
+           -e 's!@@compiler@@!$(shell $(CC) $(CFLAGS) -v 2>&1 | grep version | 
tail -1)!g' \
            -e 's/@@version@@/$(XEN_VERSION)/g' \
            -e 's/@@subversion@@/$(XEN_SUBVERSION)/g' \
            -e 's/@@extraversion@@/$(XEN_EXTRAVERSION)/g' \
diff -r 2bc9bd01b5fa -r d8ea33e7af7e xen/Rules.mk
--- a/xen/Rules.mk      Mon Mar 07 11:21:11 2011 +0000
+++ b/xen/Rules.mk      Mon Mar 07 11:21:11 2011 +0000
@@ -62,6 +62,9 @@
 
 AFLAGS-y                += -D__ASSEMBLY__
 
+# Clang's built-in assembler can't handle .code16/.code32/.code64 yet
+AFLAGS-$(clang)         += -no-integrated-as
+
 ALL_OBJS := $(ALL_OBJS-y)
 
 # Get gcc to generate the dependencies for us.
diff -r 2bc9bd01b5fa -r d8ea33e7af7e xen/arch/x86/Rules.mk
--- a/xen/arch/x86/Rules.mk     Mon Mar 07 11:21:11 2011 +0000
+++ b/xen/arch/x86/Rules.mk     Mon Mar 07 11:21:11 2011 +0000
@@ -12,9 +12,12 @@
 supervisor_mode_kernel ?= n
 
 # Solaris grabs stdarg.h and friends from the system include directory.
+# Clang likewise.
 ifneq ($(XEN_OS),SunOS)
+ifneq ($(clang),y)
 CFLAGS += -nostdinc
 endif
+endif
 
 CFLAGS += -fno-builtin -fno-common -Wredundant-decls
 CFLAGS += -iwithprefix include -Werror -Wno-pointer-arith -pipe
@@ -49,5 +52,7 @@
 x86_64 := y
 endif
 
+ifneq ($(clang),y)
 # Require GCC v3.4+ (to avoid issues with alignment constraints in Xen headers)
 $(call cc-ver-check,CC,0x030400,"Xen requires at least gcc-3.4")
+endif

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