Richard Henderson <address@hidden> writes:
On 04/21/2017 02:16 AM, Nikunj A Dadhania wrote:
Nikunj A Dadhania <address@hidden> writes:
Richard Henderson <address@hidden> writes:
On 04/21/2017 12:08 AM, Nikunj A Dadhania wrote:
David Gibson <address@hidden> writes:
[ Unknown signature status ]
Hi all,
I'm afraid I've pulled the MTTCG enablement patches for target/ppc64
out of my ppc-for-2.10 tree, since I discovered it was causing a
repeatable failure on one of the Travis builds.
Specifically, with both the LL/SC in terms of cmpxchg and
enable-mttcg-by-default patches applied, and qemu build with clang,
then make check will fail with a tcg_abort() in the powernv
boot-serial test.
I see that in temp_load(), ts->val_type is ending up being
TEMP_VAL_DEAD, and the tcg_abort() is because of that.
Following patch gets past this error...
diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index 4a1f24a..9a4ea5f 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -3169,6 +3169,7 @@ static void gen_conditional_store(DisasContext *ctx, TCGv
EA,
tcg_gen_brcond_tl(TCG_COND_NE, EA, cpu_reserve, l1);
t0 = tcg_temp_new();
+ tcg_gen_movi_tl(t0, 0);
tcg_gen_atomic_cmpxchg_tl(t0, cpu_reserve, cpu_reserve_val,
cpu_gpr[reg], ctx->mem_idx,
DEF_MEMOP(memop) | MO_ALIGN);
This *shouldn't* change anything. The arugument that you're initializing is
pure output and is equivalent to
t0 = 0;
t0 = foo();
What's the test case here?
With David's new branch that has PPC64 MTTCG -
https://github.com/dgibson/qemu/tree/mttcg
BTW, only happens with clang:
./configure --cc=clang --host-cc=clang --target-list=ppc64-softmmu
Ah! This is good information to have. Let's see if one of the sanitizers or
valgrind can spot the error or miscompilation...
Some interesting code generated for stdcx.:
0x0000000030012624: stdcx. r0,0,r3
With code compiled using GCC
---- 0000000030012624
[...]
call raise_exception_err,$0x20,$0,env,tmp0,tmp1
set_label $L1
brcond_i64 loc4,reserve_addr,ne,$L2
movi_i32 tmp0,$0x7b7
call atomic_cmpxchgq_be,$0x20,$1,tmp2,env,reserve_addr,reserve_val,r0,tmp0
setcond_i64 tmp2,tmp2,reserve_val,eq
[...]
With code compiled using clang
---- 0000000030012624
[...]
call raise_exception_err,$0x20,$0,env,tmp0,tmp1
set_label $L1
brcond_i64 loc4,reserve_addr,ne,$L2
call exit_atomic,$0x20,$0,env
setcond_i64 tmp2,tmp2,reserve_val,eq
[...]
In case of clang, movi_i32 and atomic_cmpxchgq_be is missing, and I see
a call to exit_atomic.