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[for-6.2,11/53] target/arm: Fix VLDRB/H/W for predicated elements

Message ID 20210729111512.16541-12-peter.maydell@linaro.org
State Superseded
Headers show
Series target/arm: MVE slices 3 and 4 | expand

Commit Message

Peter Maydell July 29, 2021, 11:14 a.m. UTC 
For vector loads, predicated elements are zeroed, instead of
retaining their previous values (as happens for most data
processing operations). This means we need to distinguish
"beat not executed due to ECI" (don't touch destination
element) from "beat executed but predicated out" (zero
destination element).

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

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

---
 target/arm/mve_helper.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

-- 
2.20.1
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Patch

diff --git a/target/arm/mve_helper.c b/target/arm/mve_helper.c
index bc89ce94d5a..be8b9545317 100644
--- a/target/arm/mve_helper.c
+++ b/target/arm/mve_helper.c
@@ -146,12 +146,13 @@  static void mve_advance_vpt(CPUARMState *env)
     env->v7m.vpr = vpr;
 }
 
-
+/* For loads, predicated lanes are zeroed instead of keeping their old values */
 #define DO_VLDR(OP, MSIZE, LDTYPE, ESIZE, TYPE)                         \
     void HELPER(mve_##OP)(CPUARMState *env, void *vd, uint32_t addr)    \
     {                                                                   \
         TYPE *d = vd;                                                   \
         uint16_t mask = mve_element_mask(env);                          \
+        uint16_t eci_mask = mve_eci_mask(env);                          \
         unsigned b, e;                                                  \
         /*                                                              \
          * R_SXTM allows the dest reg to become UNKNOWN for abandoned   \
@@ -159,8 +160,9 @@  static void mve_advance_vpt(CPUARMState *env)
          * then take an exception.                                      \
          */                                                             \
         for (b = 0, e = 0; b < 16; b += ESIZE, e++) {                   \
-            if (mask & (1 << b)) {                                      \
-                d[H##ESIZE(e)] = cpu_##LDTYPE##_data_ra(env, addr, GETPC()); \
+            if (eci_mask & (1 << b)) {                                  \
+                d[H##ESIZE(e)] = (mask & (1 << b)) ?                    \
+                    cpu_##LDTYPE##_data_ra(env, addr, GETPC()) : 0;     \
             }                                                           \
             addr += MSIZE;                                              \
         }                                                               \