[PATCH v3 6/9] perf test coresight: Dismiss clang warning for thread loop

Leo Yan
2025-10-06T16:21:56Z

clang-18.1.3 on Ubuntu 24.04.2 reports warning:

thread_loop.c:41:23: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
41 | : /* in */ [i] "r" (i), [len] "r" (len)
| ^
thread_loop.c:37:8: note: use constraint modifier "w"
37 | "add %[i], %[i], #1\n"
| ^~~~
| %w[i]
thread_loop.c:41:23: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
41 | : /* in */ [i] "r" (i), [len] "r" (len)
| ^
thread_loop.c:37:14: note: use constraint modifier "w"
37 | "add %[i], %[i], #1\n"
| ^~~~
| %w[i]
thread_loop.c:41:23: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
41 | : /* in */ [i] "r" (i), [len] "r" (len)
| ^
thread_loop.c:38:8: note: use constraint modifier "w"
38 | "cmp %[i], %[len]\n"
| ^~~~
| %w[i]
thread_loop.c:41:38: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
41 | : /* in */ [i] "r" (i), [len] "r" (len)
| ^
thread_loop.c:38:14: note: use constraint modifier "w"
38 | "cmp %[i], %[len]\n"
| ^~~~~~
| %w[len]

Use the modifier "w" for 32-bit register access.

Signed-off-by: Leo Yan <leo.yan@arm.com>
---
tools/perf/tests/shell/coresight/thread_loop/thread_loop.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/tests/shell/coresight/thread_loop/thread_loop.c b/tools/perf/tests/shell/coresight/thread_loop/thread_loop.c
index e05a559253ca9d9366ad321d520349042fb07fca..86f3f548b00631682767665fc5e9d5b8551a3634 100644
--- a/tools/perf/tests/shell/coresight/thread_loop/thread_loop.c
+++ b/tools/perf/tests/shell/coresight/thread_loop/thread_loop.c
@@ -34,8 +34,8 @@ static void *thrfn(void *arg)
}
asm volatile(
"loop:\n"
- "add %[i], %[i], #1\n"
- "cmp %[i], %[len]\n"
+ "add %w[i], %w[i], #1\n"
+ "cmp %w[i], %w[len]\n"
"blt loop\n"
: /* out */
: /* in */ [i] "r" (i), [len] "r" (len)

--
2.34.1