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-rw-r--r--target/arm/neon-dp.decode17
-rw-r--r--target/arm/translate-neon.inc.c3
2 files changed, 16 insertions, 4 deletions
diff --git a/target/arm/neon-dp.decode b/target/arm/neon-dp.decode
index ec3a92f..593f7ff 100644
--- a/target/arm/neon-dp.decode
+++ b/target/arm/neon-dp.decode
@@ -65,8 +65,21 @@ VCGT_U_3s 1111 001 1 0 . .. .... .... 0011 . . . 0 .... @3same
VCGE_S_3s 1111 001 0 0 . .. .... .... 0011 . . . 1 .... @3same
VCGE_U_3s 1111 001 1 0 . .. .... .... 0011 . . . 1 .... @3same
-VSHL_S_3s 1111 001 0 0 . .. .... .... 0100 . . . 0 .... @3same
-VSHL_U_3s 1111 001 1 0 . .. .... .... 0100 . . . 0 .... @3same
+# The _rev suffix indicates that Vn and Vm are reversed. This is
+# the case for shifts. In the Arm ARM these insns are documented
+# with the Vm and Vn fields in their usual places, but in the
+# assembly the operands are listed "backwards", ie in the order
+# Dd, Dm, Dn where other insns use Dd, Dn, Dm. For QEMU we choose
+# to consider Vm and Vn as being in different fields in the insn,
+# which allows us to avoid special-casing shifts in the trans_
+# function code. We would otherwise need to manually swap the operands
+# over to call Neon helper functions that are shared with AArch64,
+# which does not have this odd reversed-operand situation.
+@3same_rev .... ... . . . size:2 .... .... .... . q:1 . . .... \
+ &3same vn=%vm_dp vm=%vn_dp vd=%vd_dp
+
+VSHL_S_3s 1111 001 0 0 . .. .... .... 0100 . . . 0 .... @3same_rev
+VSHL_U_3s 1111 001 1 0 . .. .... .... 0100 . . . 0 .... @3same_rev
VMAX_S_3s 1111 001 0 0 . .. .... .... 0110 . . . 0 .... @3same
VMAX_U_3s 1111 001 1 0 . .. .... .... 0110 . . . 0 .... @3same
diff --git a/target/arm/translate-neon.inc.c b/target/arm/translate-neon.inc.c
index aefeff4..416302b 100644
--- a/target/arm/translate-neon.inc.c
+++ b/target/arm/translate-neon.inc.c
@@ -692,8 +692,7 @@ static bool trans_VMUL_p_3s(DisasContext *s, arg_3same *a)
uint32_t rn_ofs, uint32_t rm_ofs, \
uint32_t oprsz, uint32_t maxsz) \
{ \
- /* Note the operation is vshl vd,vm,vn */ \
- tcg_gen_gvec_3(rd_ofs, rm_ofs, rn_ofs, \
+ tcg_gen_gvec_3(rd_ofs, rn_ofs, rm_ofs, \
oprsz, maxsz, &OPARRAY[vece]); \
} \
DO_3SAME(INSN, gen_##INSN##_3s)