[PATCH v3] Xen: Update compiler checks

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

We have checks in both xen/compiler.h, and Config.mk.  Both are incomplete.

The check in Config.mk sees $(CC) in system and cross-compiler form, so cannot
express anything more than the global baseline.  Change it to simply 5.1.

In xen/compiler.h, rewrite the expression for clarity/brevity.

Include a GCC 12.2 check for RISCV, and include a Clang 11 baseline check.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Anthony PERARD <anthony.perard@xxxxxxxxxx>
CC: Michal Orzel <michal.orzel@xxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Julien Grall <julien@xxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

v3:
 * Reinstate the xen/compiler.h block
 * Restrict Config.mk to the baseline only
v2:
 * Change to altering Config.mk

https://gitlab.com/xen-project/people/andyhhp/xen/-/pipelines/1738778376 with
the CI changes reverted, so as to expect failures for CentOS 7 and earlier
Ubuntu Clangs.

The $(eval $(check-y)) is badly positioned:

  xen.git/xen$ make
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
    HOSTCC  tools/fixdep
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  make[1]: *** [scripts/Makefile.host:108: tools/fixdep] Error 1
    HOSTCC  tools/symbols
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  make[1]: *** [scripts/Makefile.host:108: tools/symbols] Error 1
  make: *** [Makefile:610: xen] Error 2

It is involved every time Config.mk is included, rather than once per `make`
invocation.
---
 Config.mk                  |  4 ++--
 xen/include/xen/compiler.h | 26 ++++++++++++++------------
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/Config.mk b/Config.mk
index 8a73f3da62b4..8a60d4a55abf 100644
--- a/Config.mk
+++ b/Config.mk
@@ -125,8 +125,8 @@ define cc-ver-check-closure
     endif
 endef
 
-# Require GCC v4.1+
-check-$(gcc) = $(call cc-ver-check,CC,0x040100,"Xen requires at least gcc-4.1")
+# Require GCC v5.1 as the project global baseline
+check-$(gcc) = $(call cc-ver-check,CC,0x050100,"Xen requires at least GCC 5.1")
 $(eval $(check-y))
 
 ld-ver-build-id = $(shell $(1) --build-id 2>&1 | \
diff --git a/xen/include/xen/compiler.h b/xen/include/xen/compiler.h
index 636a85bc417d..38b8fa3d386d 100644
--- a/xen/include/xen/compiler.h
+++ b/xen/include/xen/compiler.h
@@ -1,19 +1,21 @@
 #ifndef __LINUX_COMPILER_H
 #define __LINUX_COMPILER_H
 
-#if !defined(__GNUC__) || (__GNUC__ < 4)
-#error Sorry, your compiler is too old/not recognized.
-#elif CONFIG_CC_IS_GCC
-# if defined(CONFIG_ARM_32) && CONFIG_GCC_VERSION < 40900
-#  error Sorry, your version of GCC is too old - please use 4.9 or newer.
-# elif defined(CONFIG_ARM_64) && CONFIG_GCC_VERSION < 50100
-/*
- * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293
- * https://lore.kernel.org/r/20210107111841.GN1551@xxxxxxxxxxxxxxxxxxxxx
- */
-#  error Sorry, your version of GCC is too old - please use 5.1 or newer.
+#if CONFIG_CC_IS_GCC
+
+# if defined(CONFIG_RISCV) && CONFIG_GCC_VERSION < 120200
+#  error Sorry, please use GCC >= 12.2
+# elif CONFIG_GCC_VERSION < 50100
+#  error Sorry, please use GCC >= 5.1
 # endif
-#endif
+
+#elif CONFIG_CC_IS_CLANG
+
+# if CONFIG_CLANG_VERSION < 110000
+#  error Sorry, please use Clang >= 11
+# endif
+
+#endif /* Compiler checks. */
 
 #ifdef CONFIG_CC_HAS_VISIBILITY_ATTRIBUTE
 /* Results in more efficient PIC code (no indirections through GOT or PLT). */
-- 
2.39.5