target/arm: Implement MVE VPSEL

Implement the MVE VPSEL insn, which sets each byte of the destination vector Qd to the byte from either Qn or Qm depending on the value of the corresponding bit in VPR.P0. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
qemu · Aug 25, 2021 · c386443 · c386443
1 parent cce8187
commit c386443
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Showing 4 changed files with 28 additions and 2 deletions.
diff --git a/target/arm/helper-mve.h b/target/arm/helper-mve.h
@@ -82,6 +82,8 @@ DEF_HELPER_FLAGS_4(mve_vorr, TCG_CALL_NO_WG, void, env, ptr, ptr, ptr)
 DEF_HELPER_FLAGS_4(mve_vorn, TCG_CALL_NO_WG, void, env, ptr, ptr, ptr)
 DEF_HELPER_FLAGS_4(mve_veor, TCG_CALL_NO_WG, void, env, ptr, ptr, ptr)
 
+DEF_HELPER_FLAGS_4(mve_vpsel, TCG_CALL_NO_WG, void, env, ptr, ptr, ptr)
+
 DEF_HELPER_FLAGS_4(mve_vaddb, TCG_CALL_NO_WG, void, env, ptr, ptr, ptr)
 DEF_HELPER_FLAGS_4(mve_vaddh, TCG_CALL_NO_WG, void, env, ptr, ptr, ptr)
 DEF_HELPER_FLAGS_4(mve_vaddw, TCG_CALL_NO_WG, void, env, ptr, ptr, ptr)

diff --git a/target/arm/mve.decode b/target/arm/mve.decode
@@ -468,8 +468,11 @@ VSHLC             111 0 1110 1 . 1 imm:5 ... 0 1111 1100 rdm:4 qd=%qd
 # effectively "VCMP then VPST". A plain "VCMP" has a mask field of zero.
 VCMPEQ            1111 1110 0 . .. ... 1 ... 0 1111 0 0 . 0 ... 0 @vcmp
 VCMPNE            1111 1110 0 . .. ... 1 ... 0 1111 1 0 . 0 ... 0 @vcmp
-VCMPCS            1111 1110 0 . .. ... 1 ... 0 1111 0 0 . 0 ... 1 @vcmp
-VCMPHI            1111 1110 0 . .. ... 1 ... 0 1111 1 0 . 0 ... 1 @vcmp
+{
+  VPSEL           1111 1110 0 . 11 ... 1 ... 0 1111 . 0 . 0 ... 1 @2op_nosz
+  VCMPCS          1111 1110 0 . .. ... 1 ... 0 1111 0 0 . 0 ... 1 @vcmp
+  VCMPHI          1111 1110 0 . .. ... 1 ... 0 1111 1 0 . 0 ... 1 @vcmp
+}
 VCMPGE            1111 1110 0 . .. ... 1 ... 1 1111 0 0 . 0 ... 0 @vcmp
 VCMPLT            1111 1110 0 . .. ... 1 ... 1 1111 1 0 . 0 ... 0 @vcmp
 VCMPGT            1111 1110 0 . .. ... 1 ... 1 1111 0 0 . 0 ... 1 @vcmp

diff --git a/target/arm/mve_helper.c b/target/arm/mve_helper.c
@@ -1842,3 +1842,22 @@ DO_VCMP_S(vcmpge, DO_GE)
 DO_VCMP_S(vcmplt, DO_LT)
 DO_VCMP_S(vcmpgt, DO_GT)
 DO_VCMP_S(vcmple, DO_LE)
+
+void HELPER(mve_vpsel)(CPUARMState *env, void *vd, void *vn, void *vm)
+{
+    /*
+     * Qd[n] = VPR.P0[n] ? Qn[n] : Qm[n]
+     * but note that whether bytes are written to Qd is still subject
+     * to (all forms of) predication in the usual way.
+     */
+    uint64_t *d = vd, *n = vn, *m = vm;
+    uint16_t mask = mve_element_mask(env);
+    uint16_t p0 = FIELD_EX32(env->v7m.vpr, V7M_VPR, P0);
+    unsigned e;
+    for (e = 0; e < 16 / 8; e++, mask >>= 8, p0 >>= 8) {
+        uint64_t r = m[H8(e)];
+        mergemask(&r, n[H8(e)], p0);
+        mergemask(&d[H8(e)], r, mask);
+    }
+    mve_advance_vpt(env);
+}
diff --git a/target/arm/translate-mve.c b/target/arm/translate-mve.c
@@ -376,6 +376,8 @@ DO_LOGIC(VORR, gen_helper_mve_vorr)
 DO_LOGIC(VORN, gen_helper_mve_vorn)
 DO_LOGIC(VEOR, gen_helper_mve_veor)
 
+DO_LOGIC(VPSEL, gen_helper_mve_vpsel)
+
 #define DO_2OP(INSN, FN) \
     static bool trans_##INSN(DisasContext *s, arg_2op *a)       \
     {                                                           \