arch: add an option to specify the desired arch: --arch=<arch>

Sparse is universal in the sense that the same executable can
be used for all architectures. For this, most arch-specific
setting can be set with an option and the default values
are taken from the host machine.

This is working nicely for native targets. However, for cross-
compilation, while seeming to work relatively well (thanks to
the kernel build system using -m32/-m64 for all archs, for example)
things can never work 100% correctly. For example, in the case
an X86-64 host machine is used for an ARM target, the kernel
build system will call sparse with -m32, Sparse will 'autodetect'
the target arch as i386 (x86-64 + -m32) and will then predefine
the macro __i386__. Most of the time this is not a problem (at
least for the kernel) unless, of course, if the code contains
something like:
	#ifdef __i386__
	...
	#elif  __arm__
	...

So, add an option --arch=<arch> to specify the target architecture.
The native arch is still used if no such flag is given.

Reported-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>

6 files changed, 182 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index 58c12c77..91ecc12c 100644
--- a/lib.c
+++ b/lib.c
@@ -1046,6 +1046,73 @@ static char **handle_switch_x(char *arg, char **next)
 }
 
 
+static char **handle_arch(char *arg, char **next)
+{
+	static const struct arch {
+		const char *name;
+		char mach;
+		char bits;
+		bool big_endian:1;
+	} archs[] = {
+		{ "aarch64",	MACH_ARM64,	64, 0 },
+		{ "arm64",	MACH_ARM64,	64, 0 },
+		{ "arm",	MACH_ARM,	32, 0 },
+		{ "i386",	MACH_I386,	32, 0 },
+		{ "m68k",	MACH_M68K,	32, 0 },
+		{ "mips",	MACH_MIPS32,	0,  1 },
+		{ "powerpc",	MACH_PPC32,	0,  1 },
+		{ "ppc",	MACH_PPC32,	0,  1 },
+		{ "riscv",	MACH_RISCV32,	0,  0 },
+		{ "s390x",	MACH_S390X,	64, 1 },
+		{ "s390",	MACH_S390,	32, 1 },
+		{ "sparc",	MACH_SPARC32,	0,  1 },
+		{ "x86_64",	MACH_X86_64,	64, 0 },
+		{ "x86-64",	MACH_X86_64,	64, 0 },
+		{ NULL },
+	};
+	const struct arch *p;
+
+	if (*arg++ != '=')
+		die("missing argument for --arch option");
+
+	for (p = &archs[0]; p->name; p++) {
+		size_t len = strlen(p->name);
+		if (strncmp(p->name, arg, len) == 0) {
+			const char *suf = arg + len;
+			int bits = p->bits;
+
+			arch_mach = p->mach;
+			if (bits == 0) {
+				if (!strcmp(suf, "")) {
+					bits = 32;
+				} else if (!strcmp(suf, "32")) {
+					bits = 32;
+				} else if (!strcmp(suf, "64")) {
+					bits = 64;
+					arch_mach += 1;
+				} else {
+					die("invalid architecture: %s", arg);
+				}
+			} else {
+				if (strcmp(suf, ""))
+					die("invalid architecture: %s", arg);
+			}
+
+			// adjust the arch size (but keep x32 & llp64)
+			if (bits == 32)
+				arch_m64 = ARCH_LP32;
+			else if (bits == 64 && arch_m64 == ARCH_LP32)
+				arch_m64 = ARCH_LP64;
+			if (p->big_endian)
+				arch_big_endian = 1;
+
+			break;
+		}
+	}
+
+	return next;
+}
+
 static char **handle_version(char *arg, char **next)
 {
 	printf("%s\n", SPARSE_VERSION);
@@ -1078,6 +1145,7 @@ struct switches {
 static char **handle_long_options(char *arg, char **next)
 {
 	static struct switches cmd[] = {
+		{ "arch", handle_arch, 1 },
 		{ "param", handle_param, 1 },
 		{ "version", handle_version },
 		{ NULL, NULL }
diff --git a/sparse.1 b/sparse.1
index beb48442..be38f688 100644
--- a/sparse.1
+++ b/sparse.1
@@ -423,6 +423,14 @@ Sparse does not issue these warnings by default.
 .
 .SH MISC OPTIONS
 .TP
+.B \-\-arch=\fIARCH\fR
+Specify the target architecture.
+For architectures having both a 32-bit and a 64-bit variant (mips, powerpc,
+riscv & sparc) the architecture name can be suffixed with \fI32\fR or \fI64\fR.
+
+The default architecture & size is the one of the machine used to build Sparse.
+.
+.TP
 .B \-gcc-base-dir \fIdir\fR
 Look for compiler-provided system headers in \fIdir\fR/include/ and \fIdir\fR/include-fixed/.
 .
diff --git a/validation/arch/arm.c b/validation/arch/arm.c
new file mode 100644
index 00000000..4eb804de
--- /dev/null
+++ b/validation/arch/arm.c
@@ -0,0 +1,27 @@
+__arm__
+__aarch64__
+__i386__
+__x86_64__
+__LP64__
+__BYTE_ORDER__
+__SIZEOF_INT__
+__SIZEOF_LONG__
+__SIZE_TYPE__
+
+/*
+ * check-name: arch/arm
+ * check-command: sparse --arch=arm -E $file
+ *
+ * check-output-start
+
+1
+__aarch64__
+__i386__
+__x86_64__
+__LP64__
+1234
+4
+4
+unsigned int
+ * check-output-end
+ */
diff --git a/validation/arch/arm64.c b/validation/arch/arm64.c
new file mode 100644
index 00000000..12f839cc
--- /dev/null
+++ b/validation/arch/arm64.c
@@ -0,0 +1,23 @@
+__aarch64__
+__x86_64__
+__LP64__
+__BYTE_ORDER__
+__SIZEOF_INT__
+__SIZEOF_LONG__
+__SIZE_TYPE__
+
+/*
+ * check-name: arch/arm64
+ * check-command: sparse --arch=arm64 -E $file
+ *
+ * check-output-start
+
+1
+__x86_64__
+1
+1234
+4
+8
+unsigned long
+ * check-output-end
+ */
diff --git a/validation/arch/mips32.c b/validation/arch/mips32.c
new file mode 100644
index 00000000..339218b6
--- /dev/null
+++ b/validation/arch/mips32.c
@@ -0,0 +1,29 @@
+__mips__
+__mips
+__mips64__
+__i386__
+__x86_64__
+__LP64__
+__BYTE_ORDER__
+__SIZEOF_INT__
+__SIZEOF_LONG__
+__SIZE_TYPE__
+
+/*
+ * check-name: arch/mips32
+ * check-command: sparse --arch=mips32 -E $file
+ *
+ * check-output-start
+
+1
+32
+__mips64__
+__i386__
+__x86_64__
+__LP64__
+4321
+4
+4
+unsigned int
+ * check-output-end
+ */
diff --git a/validation/arch/riscv64.c b/validation/arch/riscv64.c
new file mode 100644
index 00000000..9da7a7de
--- /dev/null
+++ b/validation/arch/riscv64.c
@@ -0,0 +1,27 @@
+__riscv
+__riscv_xlen
+__i386__
+__x86_64__
+__LP64__
+__BYTE_ORDER__
+__SIZEOF_INT__
+__SIZEOF_LONG__
+__SIZE_TYPE__
+
+/*
+ * check-name: arch/riscv64
+ * check-command: sparse --arch=riscv64 -E $file
+ *
+ * check-output-start
+
+1
+64
+__i386__
+__x86_64__
+1
+1234
+4
+8
+unsigned long
+ * check-output-end
+ */