[PATCH v1 1/6] RISC-V: Respect -Wsparse-error for -march errors

[Palmer Dabbelt <palmer@rivosinc.com>]

Parsing RISC-V ISA strings is extremely complicated: there are many
extensions, versions of extensions, versions of the ISA string rules,
and a bunch of unwritten rules to deal with all the bugs that fell out
of that complexity.

Rather than forcing users to see an error when the ISA string parsing
fails, just stop parsing where we get lost.  Changes tend to end up at
the end of the ISA string, so that's probably going to work (and if
it doesn't there's a warning to true and clue folks in).

This does have the oddity in that "-Wsparse-error -march=..." behaves
differently than "-march... -Wsparse-error", but that's already the case
for "--arch=... -march=..." and "-march=... --arch=...".  Both
"-Wsparse-error" and "--arch" are sparse-specific arguments, so they're
probably both going to be in the same place.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
---
 lib.h          |  5 +++++
 options.c      |  6 ------
 target-riscv.c | 16 ++++++++++++++--
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/lib.h b/lib.h
index b96e3192..2c0d7116 100644
--- a/lib.h
+++ b/lib.h
@@ -125,6 +125,11 @@ enum phase {
 #define	PASS_OPTIM		(1UL << PASS__OPTIM)
 #define	PASS_FINAL		(1UL << PASS__FINAL)
 
+enum flag_type {
+	FLAG_OFF,
+	FLAG_ON,
+	FLAG_FORCE_OFF,
+};
 
 extern void add_pre_buffer(const char *fmt, ...) FORMAT_ATTR(1);
 extern void predefine(const char *name, int weak, const char *fmt, ...) FORMAT_ATTR(3);
diff --git a/options.c b/options.c
index 6704fc8d..41a98240 100644
--- a/options.c
+++ b/options.c
@@ -23,12 +23,6 @@
 # define __GNUC_PATCHLEVEL__ 0
 #endif
 
-enum flag_type {
-	FLAG_OFF,
-	FLAG_ON,
-	FLAG_FORCE_OFF
-};
-
 int die_if_error = 0;
 int do_output = 1;
 int gcc_major = __GNUC__;
diff --git a/target-riscv.c b/target-riscv.c
index 6d9113c1..f5cc6cc3 100644
--- a/target-riscv.c
+++ b/target-riscv.c
@@ -3,6 +3,7 @@
 #include "target.h"
 #include "machine.h"
 #include <string.h>
+#include <stdio.h>
 
 #define RISCV_32BIT	(1 << 0)
 #define RISCV_64BIT	(1 << 1)
@@ -60,7 +61,18 @@ static void parse_march_riscv(const char *arg)
 			goto ext;
 		}
 	}
-	die("invalid argument to '-march': '%s'\n", arg);
+
+unknown:
+	/*
+	 * This behaves like do_warn() / do_error(), but we don't have a
+	 * position so it's just inline here.
+	 */
+	fflush(stdout);
+	fprintf(stderr, "%s: invalid argument to '-march': '%s'\n",
+		Wsparse_error == FLAG_ON ? "error" : "warning", arg);
+	if (Wsparse_error == FLAG_ON)
+		has_error |= ERROR_CURR_PHASE;
+	return;
 
 ext:
 	for (i = 0; i < ARRAY_SIZE(extensions); i++) {
@@ -73,7 +85,7 @@ ext:
 		}
 	}
 	if (arg[0])
-		die("invalid argument to '-march': '%s'\n", arg);
+		goto unknown;
 }
 
 static void init_riscv(const struct target *self)
-- 
2.34.1