The variables data, func, thread and cur are input operands for
the asm statement in run_thread(). The assembly code clobbers
these inputs.
From the gcc documentation chapter Extended-Asm, Input Operands:
"It is not possible to use clobbers to inform the compiler that
the values in these inputs are changing. One common work-around
is to tie the changing input variable to an output variable that
never gets used."
Add unused output variables and fix the asm constraints in
run_thread().
Signed-off-by: Volker Rümelin <vr_q...@t-online.de>
---
src/stacks.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/src/stacks.c b/src/stacks.c
index 2fe1bfb..ef0aba1 100644
--- a/src/stacks.c
+++ b/src/stacks.c
@@ -565,6 +565,7 @@ run_thread(void (*func)(void*), void *data)
thread->stackpos = (void*)thread + THREADSTACKSIZE;
struct thread_info *cur = getCurThread();
hlist_add_after(&thread->node, &cur->node);
+ u32 unused_a, unused_b, unused_c, unused_d;
asm volatile(
// Start thread
" pushl $1f\n" // store return pc
@@ -576,14 +577,15 @@ run_thread(void (*func)(void*), void *data)
// End thread
" movl %%ebx, %%eax\n" // %eax = thread
" movl 4(%%ebx), %%ebx\n" // %ebx = thread->node.next
- " movl (%5), %%esp\n" // %esp = MainThread.stackpos
- " calll %4\n" // call __end_thread(thread)
+ " movl (%9), %%esp\n" // %esp = MainThread.stackpos
+ " calll %8\n" // call __end_thread(thread)
" movl -4(%%ebx), %%esp\n" // %esp = next->stackpos
" popl %%ebp\n" // restore %ebp
" retl\n" // restore pc
"1:\n"
- : "+a"(data), "+c"(func), "+b"(thread), "+d"(cur)
- : "m"(*(u8*)__end_thread), "m"(MainThread)
+ : "=a"(unused_a), "=c"(unused_c), "=b"(unused_b), "=d"(unused_d)
+ : "0"(data), "1"(func), "2"(thread), "3"(cur),
+ "m"(*(u8*)__end_thread), "m"(MainThread)
: "esi", "edi", "cc", "memory");
return;
--
2.26.2
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