[PATCH 2/2] target/sparc: Loosen decode of RDY for v7

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

Bits [18:0] are not decoded with v7, and for v8 unused values
of rs1 simply produce undefined results.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/sparc/translate.c  | 24 +++++++++++++-----------
 target/sparc/insns.decode | 12 ++++++++++--
 2 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/target/sparc/translate.c b/target/sparc/translate.c
index c2ffd965d8..69d5883dec 100644
--- a/target/sparc/translate.c
+++ b/target/sparc/translate.c
@@ -2865,22 +2865,24 @@ static bool do_rd_special(DisasContext *dc, bool priv, int rd,
     return advance_pc(dc);
 }
 
-static TCGv do_rdy(DisasContext *dc, TCGv dst)
+static TCGv do_rdy_1(DisasContext *dc, TCGv dst)
 {
     return cpu_y;
 }
 
-static bool trans_RDY(DisasContext *dc, arg_RDY *a)
+static bool do_rdy(DisasContext *dc, int rd)
 {
-    /*
-     * TODO: Need a feature bit for sparcv8.  In the meantime, treat all
-     * 32-bit cpus like sparcv7, which ignores the rs1 field.
-     * This matches after all other ASR, so Leon3 Asr17 is handled first.
-     */
-    if (avail_64(dc) && a->rs1 != 0) {
-        return false;
-    }
-    return do_rd_special(dc, true, a->rd, do_rdy);
+    return do_rd_special(dc, true, rd, do_rdy_1);
+}
+
+static bool trans_RDY_v7(DisasContext *dc, arg_RDY_v7 *a)
+{
+    return avail_32(dc) && do_rdy(dc, a->rd);
+}
+
+static bool trans_RDY_v9(DisasContext *dc, arg_RDY_v9 *a)
+{
+    return avail_64(dc) && do_rdy(dc, a->rd);
 }
 
 static TCGv do_rd_leon3_config(DisasContext *dc, TCGv dst)
diff --git a/target/sparc/insns.decode b/target/sparc/insns.decode
index 1b1b85e9c2..74848996ae 100644
--- a/target/sparc/insns.decode
+++ b/target/sparc/insns.decode
@@ -91,6 +91,7 @@ CALL    01 i:s30
     STBAR_v9        10 00000 101000 01111 0 0000000000000
     MEMBAR          10 00000 101000 01111 1 000000 cmask:3 mmask:4
 
+    RDY_v9          10 rd:5  101000 00000 0 0000000000000
     RDCCR           10 rd:5  101000 00010 0 0000000000000
     RDASI           10 rd:5  101000 00011 0 0000000000000
     RDTICK          10 rd:5  101000 00100 0 0000000000000
@@ -118,8 +119,15 @@ CALL    01 i:s30
   # This confirms that bit 13 is ignored, as 0x8143c000 is STBAR.
   STBAR_v8          10 ----- 101000 01111 - -------------
 
-  # Before v8, all rs1 accepted; otherwise rs1==0.
-  RDY               10 rd:5  101000 rs1:5 0 0000000000000
+  # For v7, bits [18:0] are ignored.
+  # For v8, bits [18:14], aka rs1, are repurposed and rs1 = 0 is RDY,
+  # and other values are RDASR.  However, the v8 manual explicitly
+  # says that rs1 in 1..14 yield undefined results and do not cause
+  # an illegal instruction trap, and rs1 in 16..31 are available for
+  # implementation specific usage.
+  # Implement not causing an illegal instruction trap for v8 by
+  # continuing to interpret unused values per v7, i.e. as RDY.
+  RDY_v7            10 rd:5  101000 ----- - -------------
 }
 
 {
-- 
2.43.0