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Date:   Mon, 19 Sep 2022 10:08:28 -0700
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Subject: [PATCH v4] Makefile.compiler: replace cc-ifversion with
 compiler-specific macros
From:   Nick Desaulniers <ndesaulniers@google.com>
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     Michal Marek <michal.lkml@markovi.net>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        clang-built-linux <llvm@lists.linux.dev>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Bill Wendling <morbo@google.com>,
        Nathan Chancellor <nathan@kernel.org>
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Precedence: bulk

cc-ifversion is GCC specific. Replace it with compiler specific
variants. Update the users of cc-ifversion to use these new macros.

Link: https://github.com/ClangBuiltLinux/linux/issues/350
Link: https://lore.kernel.org/llvm/CAGG=3QWSAUakO42kubrCap8fp-gm1ERJJAYXTnP1iHk_wrH=BQ@mail.gmail.com/
Suggested-by: Bill Wendling <morbo@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
Changes v3 -> v4:
* Split into its own patch again from series, as per Masahiro.
* Rebase on top of b0839b281c427e844143dba3893e25c83cdd6c17 and update
  clang -Wformat logic in scripts/Makefile.extrawarn, as per Masahiro.

 Documentation/kbuild/makefiles.rst          | 29 ++++++++++++---------
 Makefile                                    |  6 ++---
 drivers/gpu/drm/amd/display/dc/dml/Makefile |  2 +-
 scripts/Makefile.compiler                   | 10 ++++---
 scripts/Makefile.extrawarn                  |  4 +--
 5 files changed, 29 insertions(+), 22 deletions(-)

diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst
index 11a296e52d68..ee7e3ea1fbe1 100644
--- a/Documentation/kbuild/makefiles.rst
+++ b/Documentation/kbuild/makefiles.rst
@@ -682,22 +682,27 @@ more details, with real examples.
 	In the above example, -Wno-unused-but-set-variable will be added to
 	KBUILD_CFLAGS only if gcc really accepts it.
 
-    cc-ifversion
-	cc-ifversion tests the version of $(CC) and equals the fourth parameter
-	if version expression is true, or the fifth (if given) if the version
-	expression is false.
+    gcc-min-version
+	gcc-min-version tests if the value of $(CONFIG_GCC_VERSION) is greater than
+	or equal to the provided value and evaluates to y if so.
 
 	Example::
 
-		#fs/reiserfs/Makefile
-		ccflags-y := $(call cc-ifversion, -lt, 0402, -O1)
+		cflags-$(call gcc-min-version, 70100) := -foo
 
-	In this example, ccflags-y will be assigned the value -O1 if the
-	$(CC) version is less than 4.2.
-	cc-ifversion takes all the shell operators:
-	-eq, -ne, -lt, -le, -gt, and -ge
-	The third parameter may be a text as in this example, but it may also
-	be an expanded variable or a macro.
+	In this example, cflags-y will be assigned the value -foo if $(CC) is gcc and
+	$(CONFIG_GCC_VERSION) is >= 7.1.
+
+    clang-min-version
+	clang-min-version tests if the value of $(CONFIG_CLANG_VERSION) is greater
+	than or equal to the provided value and evaluates to y if so.
+
+	Example::
+
+		cflags-$(call clang-min-version, 110000) := -foo
+
+	In this example, cflags-y will be assigned the value -foo if $(CC) is clang
+	and $(CONFIG_CLANG_VERSION) is >= 11.0.0.
 
     cc-cross-prefix
 	cc-cross-prefix is used to check if there exists a $(CC) in path with
diff --git a/Makefile b/Makefile
index 298f69060f10..411c8480b37e 100644
--- a/Makefile
+++ b/Makefile
@@ -790,7 +790,6 @@ KBUILD_CFLAGS += $(stackp-flags-y)
 
 KBUILD_CFLAGS-$(CONFIG_WERROR) += -Werror
 KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds
-KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
 
 ifdef CONFIG_CC_IS_CLANG
 KBUILD_CPPFLAGS += -Qunused-arguments
@@ -972,7 +971,6 @@ ifdef CONFIG_CC_IS_GCC
 KBUILD_CFLAGS += -Wno-maybe-uninitialized
 endif
 
-ifdef CONFIG_CC_IS_GCC
 # The allocators already balk at large sizes, so silence the compiler
 # warnings for bounds checks involving those possible values. While
 # -Wno-alloc-size-larger-than would normally be used here, earlier versions
@@ -984,8 +982,8 @@ ifdef CONFIG_CC_IS_GCC
 # ignored, continuing to default to PTRDIFF_MAX. So, left with no other
 # choice, we must perform a versioned check to disable this warning.
 # https://lore.kernel.org/lkml/20210824115859.187f272f@canb.auug.org.au
-KBUILD_CFLAGS += $(call cc-ifversion, -ge, 0901, -Wno-alloc-size-larger-than)
-endif
+KBUILD_CFLAGS-$(call gcc-min-version, 90100) += -Wno-alloc-size-larger-than
+KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
 
 # disable invalid "can't wrap" optimizations for signed / pointers
 KBUILD_CFLAGS	+= -fno-strict-overflow
diff --git a/drivers/gpu/drm/amd/display/dc/dml/Makefile b/drivers/gpu/drm/amd/display/dc/dml/Makefile
index cb81ed2fbd53..d70838edba80 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/Makefile
+++ b/drivers/gpu/drm/amd/display/dc/dml/Makefile
@@ -34,7 +34,7 @@ dml_ccflags := -mhard-float -maltivec
 endif
 
 ifdef CONFIG_CC_IS_GCC
-ifeq ($(call cc-ifversion, -lt, 0701, y), y)
+ifneq ($(call gcc-min-version, 70100),y)
 IS_OLD_GCC = 1
 endif
 endif
diff --git a/scripts/Makefile.compiler b/scripts/Makefile.compiler
index 94d0d40cddb3..9d18fb91890e 100644
--- a/scripts/Makefile.compiler
+++ b/scripts/Makefile.compiler
@@ -61,9 +61,13 @@ cc-option-yn = $(call try-run,\
 cc-disable-warning = $(call try-run,\
 	$(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
 
-# cc-ifversion
-# Usage:  EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
-cc-ifversion = $(shell [ $(CONFIG_GCC_VERSION)0 $(1) $(2)000 ] && echo $(3) || echo $(4))
+# gcc-min-version
+# Usage: cflags-$(call gcc-min-version, 70100) += -foo
+gcc-min-version = $(shell [ $(CONFIG_GCC_VERSION) -ge $(1) ] && echo y)
+
+# clang-min-version
+# Usage: cflags-$(call clang-min-version, 110000) += -foo
+clang-min-version = $(shell [ $(CONFIG_CLANG_VERSION) -ge $(1) ] && echo y)
 
 # ld-option
 # Usage: KBUILD_LDFLAGS += $(call ld-option, -X, -Y)
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 6ae482158bc4..5769c1939d40 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -48,7 +48,7 @@ else
 ifdef CONFIG_CC_IS_CLANG
 KBUILD_CFLAGS += -Wno-initializer-overrides
 # Clang before clang-16 would warn on default argument promotions.
-ifeq ($(shell [ $(CONFIG_CLANG_VERSION) -lt 160000 ] && echo y),y)
+ifneq ($(call clang-min-version, 160000),y)
 # Disable -Wformat
 KBUILD_CFLAGS += -Wno-format
 # Then re-enable flags that were part of the -Wformat group that aren't
@@ -56,7 +56,7 @@ KBUILD_CFLAGS += -Wno-format
 KBUILD_CFLAGS += -Wformat-extra-args -Wformat-invalid-specifier
 KBUILD_CFLAGS += -Wformat-zero-length -Wnonnull
 # Requires clang-12+.
-ifeq ($(shell [ $(CONFIG_CLANG_VERSION) -ge 120000 ] && echo y),y)
+ifeq ($(call clang-min-version, 120000),y)
 KBUILD_CFLAGS += -Wformat-insufficient-args
 endif
 endif
-- 
2.37.3.968.ga6b4b080e4-goog