[Qemu-devel] [PATCH v3 59/69] target/arm: Convert T16, nop hints

[Richard Henderson <richard.henderson@linaro.org>]

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/translate.c |  3 +--
 target/arm/t16.decode  | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/target/arm/translate.c b/target/arm/translate.c
index ec5b095bd1..1bbfea8ea4 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -10868,8 +10868,7 @@ static void disas_thumb_insn(DisasContext *s, uint32_t insn)
 
         case 15: /* IT, nop-hint.  */
             if ((insn & 0xf) == 0) {
-                gen_nop_hint(s, (insn >> 4) & 0xf);
-                break;
+                goto illegal_op; /* nop hint, in decodetree */
             }
             /*
              * IT (If-Then)
diff --git a/target/arm/t16.decode b/target/arm/t16.decode
index 19a442b894..5829b9a58c 100644
--- a/target/arm/t16.decode
+++ b/target/arm/t16.decode
@@ -19,6 +19,7 @@
 # This file is processed by scripts/decodetree.py
 #
 
+&empty           !extern
 &s_rrr_shi       !extern s rd rn rm shim shty
 &s_rrr_shr       !extern s rn rd rm rs shty
 &s_rri_rot       !extern s rn rd imm rot
@@ -204,3 +205,19 @@ SETEND          1011 0110 010 1 E:1 000         &setend
 REV             1011 1010 00 ... ...            @rdm
 REV16           1011 1010 01 ... ...            @rdm
 REVSH           1011 1010 11 ... ...            @rdm
+
+# Hints
+
+{
+  YIELD         1011 1111 0001 0000
+  WFE           1011 1111 0010 0000
+  WFI           1011 1111 0011 0000
+
+  # TODO: Implement SEV, SEVL; may help SMP performance.
+  # SEV         1011 1111 0100 0000
+  # SEVL        1011 1111 0101 0000
+
+  # The canonical nop has the second nibble as 0000, but the whole of the
+  # rest of the space is a reserved hint, behaves as nop.
+  NOP           1011 1111 ---- 0000
+}
-- 
2.17.1