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<body><span class="vcard"><a class="email" href="mailto:echristo@gmail.com" title="Eric Christopher <echristo@gmail.com>"> <span class="fn">Eric Christopher</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED WORKSFORME - 65536 out of the range of constraint 'I'"
href="https://llvm.org/bugs/show_bug.cgi?id=26874">bug 26874</a>
<br>
<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
<tr>
<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
</td>
</tr>
<tr>
<td style="text-align:right;">CC</td>
<td>
</td>
<td>echristo@gmail.com
</td>
</tr>
<tr>
<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>WORKSFORME
</td>
</tr></table>
<p>
<div>
<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED WORKSFORME - 65536 out of the range of constraint 'I'"
href="https://llvm.org/bugs/show_bug.cgi?id=26874#c2">Comment # 2</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED WORKSFORME - 65536 out of the range of constraint 'I'"
href="https://llvm.org/bugs/show_bug.cgi?id=26874">bug 26874</a>
from <span class="vcard"><a class="email" href="mailto:echristo@gmail.com" title="Eric Christopher <echristo@gmail.com>"> <span class="fn">Eric Christopher</span></a>
</span></b>
<pre>With the testcase I've created from your report and current ToT it works for
me:
dzur:~/tmp> ~/builds/build-llvm/bin/clang -target aarch64-linux-gnu -S foo.c
-O0 -o -
.text
.file "foo.c"
.globl arch_spin_trylock
.p2align 2
.type arch_spin_trylock,@function
arch_spin_trylock: // @arch_spin_trylock
// BB#0: // %entry
sub sp, sp, #16 // =16
str x0, [sp, #8]
ldr x0, [sp, #8]
//APP
.Ltmp1:
ldaxr w8, [x0]
eor w9, w8, w8, ror #16
cbnz w9, .Ltmp2
add w8, w8, #16, lsl #12 // =65536
stxr w9, w8, [x0]
cbnz w9, .Ltmp1
.Ltmp2:
//NO_APP
str w8, [sp]
str w9, [sp, #4]
ldr w8, [sp, #4]
cmp w8, #0 // =0
cset w8, ne
eor w8, w8, #0x1
and w0, w8, #0x1
add sp, sp, #16 // =16
ret
.Lfunc_end0:
.size arch_spin_trylock, .Lfunc_end0-arch_spin_trylock
.ident "clang version 3.9.0 (trunk 262996) (llvm/trunk 262998)"
.section ".note.GNU-stack","",@progbits
dzur:~/tmp> ~/builds/build-llvm/bin/clang -target aarch64-linux-gnu -S foo.c
-O3 -o -
.text
.file "foo.c"
.globl arch_spin_trylock
.p2align 2
.type arch_spin_trylock,@function
arch_spin_trylock: // @arch_spin_trylock
// BB#0: // %entry
sub sp, sp, #16 // =16
//APP
.Ltmp1:
ldaxr w8, [x0]
eor w9, w8, w8, ror #16
cbnz w9, .Ltmp2
add w8, w8, #16, lsl #12 // =65536
stxr w9, w8, [x0]
cbnz w9, .Ltmp1
.Ltmp2:
//NO_APP
cmp w9, #0 // =0
cset w0, eq
str w8, [sp, #8]
add sp, sp, #16 // =16
ret
.Lfunc_end0:
.size arch_spin_trylock, .Lfunc_end0-arch_spin_trylock
.ident "clang version 3.9.0 (trunk 262996) (llvm/trunk 262998)"
.section ".note.GNU-stack","",@progbits
dzur:~/tmp> cat foo.c
#include <inttypes.h>
#define TICKET_SHIFT 16
typedef struct {
uint16_t owner;
uint16_t next;
} __attribute__((aligned(4))) arch_spinlock_t;
int arch_spin_trylock(arch_spinlock_t *lock) {
unsigned int tmp;
arch_spinlock_t lockval;
asm volatile(
"1: ldaxr %w0, %2\n"
" eor %w1, %w0, %w0, ror #16\n"
" cbnz %w1, 2f\n"
" add %w0, %w0, %3\n"
" stxr %w1, %w0, %2\n"
" cbnz %w1, 1b\n"
"2:"
: "=&r"(lockval), "=&r"(tmp), "+Q"(*lock)
: "I"(1 << TICKET_SHIFT)
: "memory");
return !tmp;
}</pre>
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