diff mbox series

[v2,06/15] target/arm: Clear unused predicate bits for LD1RQ

Message ID 20180926192323.12659-7-richard.henderson@linaro.org
State Superseded
Headers show
Series target/arm: sve system mode patches | expand

Commit Message

Richard Henderson Sept. 26, 2018, 7:23 p.m. UTC 
The 16-byte load only uses 16 predicate bits.  But while
reusing the other load infrastructure, we find other bits
that are set and trigger an assert.  To avoid this and
retain the assert, zero-extend the predicate that we pass
to the LD1 helper.

Tested-by: Laurent Desnogues <laurent.desnogues@gmail.com>

Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 target/arm/translate-sve.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

-- 
2.17.1

Comments

Peter Maydell Oct. 2, 2018, 10:23 a.m. UTC | #1 
On 26 September 2018 at 20:23, Richard Henderson
<richard.henderson@linaro.org> wrote:
> The 16-byte load only uses 16 predicate bits.  But while

> reusing the other load infrastructure, we find other bits

> that are set and trigger an assert.  To avoid this and

> retain the assert, zero-extend the predicate that we pass

> to the LD1 helper.

>

> Tested-by: Laurent Desnogues <laurent.desnogues@gmail.com>

> Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com>

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>


Reviewed-by: Peter Maydell <peter.maydell@linaro.org>


thanks
-- PMM
diff mbox series

Patch

diff --git a/target/arm/translate-sve.c b/target/arm/translate-sve.c
index 667879564f..4ee3bbca29 100644
--- a/target/arm/translate-sve.c
+++ b/target/arm/translate-sve.c
@@ -4765,12 +4765,33 @@  static void do_ldrq(DisasContext *s, int zt, int pg, TCGv_i64 addr, int msz)
     unsigned vsz = vec_full_reg_size(s);
     TCGv_ptr t_pg;
     TCGv_i32 desc;
+    int poff;
 
     /* Load the first quadword using the normal predicated load helpers.  */
     desc = tcg_const_i32(simd_desc(16, 16, zt));
-    t_pg = tcg_temp_new_ptr();
 
-    tcg_gen_addi_ptr(t_pg, cpu_env, pred_full_reg_offset(s, pg));
+    poff = pred_full_reg_offset(s, pg);
+    if (vsz > 16) {
+        /*
+         * Zero-extend the first 16 bits of the predicate into a temporary.
+         * This avoids triggering an assert making sure we don't have bits
+         * set within a predicate beyond VQ, but we have lowered VQ to 1
+         * for this load operation.
+         */
+        TCGv_i64 tmp = tcg_temp_new_i64();
+#ifdef HOST_WORDS_BIGENDIAN
+        poff += 6;
+#endif
+        tcg_gen_ld16u_i64(tmp, cpu_env, poff);
+
+        poff = offsetof(CPUARMState, vfp.preg_tmp);
+        tcg_gen_st_i64(tmp, cpu_env, poff);
+        tcg_temp_free_i64(tmp);
+    }
+
+    t_pg = tcg_temp_new_ptr();
+    tcg_gen_addi_ptr(t_pg, cpu_env, poff);
+
     fns[msz](cpu_env, t_pg, addr, desc);
 
     tcg_temp_free_ptr(t_pg);