[Qemu-devel] [PATCH 15/67] target/arm: Convert Saturating addition and subtraction

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

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/helper.h    |  1 -
 target/arm/op_helper.c | 15 ---------
 target/arm/translate.c | 74 +++++++++++++++++++++++++++---------------
 target/arm/a32.decode  | 10 ++++++
 target/arm/t32.decode  |  9 +++++
 5 files changed, 66 insertions(+), 43 deletions(-)

diff --git a/target/arm/helper.h b/target/arm/helper.h
index 132aa1682e..1fb2cb5a77 100644
--- a/target/arm/helper.h
+++ b/target/arm/helper.h
@@ -6,7 +6,6 @@ DEF_HELPER_3(add_saturate, i32, env, i32, i32)
 DEF_HELPER_3(sub_saturate, i32, env, i32, i32)
 DEF_HELPER_3(add_usaturate, i32, env, i32, i32)
 DEF_HELPER_3(sub_usaturate, i32, env, i32, i32)
-DEF_HELPER_2(double_saturate, i32, env, s32)
 DEF_HELPER_FLAGS_2(sdiv, TCG_CALL_NO_RWG_SE, s32, s32, s32)
 DEF_HELPER_FLAGS_2(udiv, TCG_CALL_NO_RWG_SE, i32, i32, i32)
 DEF_HELPER_FLAGS_1(rbit, TCG_CALL_NO_RWG_SE, i32, i32)
diff --git a/target/arm/op_helper.c b/target/arm/op_helper.c
index 1ab91f915e..142239b03a 100644
--- a/target/arm/op_helper.c
+++ b/target/arm/op_helper.c
@@ -135,21 +135,6 @@ uint32_t HELPER(sub_saturate)(CPUARMState *env, uint32_t a, uint32_t b)
     return res;
 }
 
-uint32_t HELPER(double_saturate)(CPUARMState *env, int32_t val)
-{
-    uint32_t res;
-    if (val >= 0x40000000) {
-        res = ~SIGNBIT;
-        env->QF = 1;
-    } else if (val <= (int32_t)0xc0000000) {
-        res = SIGNBIT;
-        env->QF = 1;
-    } else {
-        res = val << 1;
-    }
-    return res;
-}
-
 uint32_t HELPER(add_usaturate)(CPUARMState *env, uint32_t a, uint32_t b)
 {
     uint32_t res = a + b;
diff --git a/target/arm/translate.c b/target/arm/translate.c
index 354a52d36c..85f829c1bb 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -8174,6 +8174,47 @@ static bool trans_UMAAL(DisasContext *s, arg_UMAAL *a)
     return true;
 }
 
+/*
+ * Saturating addition and subtraction
+ */
+
+static bool op_qaddsub(DisasContext *s, arg_rrr *a, bool add, bool doub)
+{
+    TCGv_i32 t0, t1;
+
+    if (s->thumb
+        ? !arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)
+        : !ENABLE_ARCH_5TE) {
+        return false;
+    }
+
+    t0 = load_reg(s, a->rm);
+    t1 = load_reg(s, a->rn);
+    if (doub) {
+        gen_helper_add_saturate(t1, cpu_env, t1, t1);
+    }
+    if (add) {
+        gen_helper_add_saturate(t0, cpu_env, t0, t1);
+    } else {
+        gen_helper_sub_saturate(t0, cpu_env, t0, t1);
+    }
+    tcg_temp_free_i32(t1);
+    store_reg(s, a->rd, t0);
+    return true;
+}
+
+#define DO_QADDSUB(NAME, ADD, DOUB) \
+static bool trans_##NAME(DisasContext *s, arg_rrr *a)    \
+{                                                        \
+    return op_qaddsub(s, a, ADD, DOUB);                  \
+}
+
+DO_QADDSUB(QADD, true, false)
+DO_QADDSUB(QSUB, false, false)
+DO_QADDSUB(QDADD, true, true)
+DO_QADDSUB(QDSUB, false, true)
+
+#undef DO_QADDSUB
 
 /*
  * Legacy decoder.
@@ -8582,21 +8623,10 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn)
             store_reg(s, rd, tmp);
             break;
         }
-        case 0x5: /* saturating add/subtract */
-            ARCH(5TE);
-            rd = (insn >> 12) & 0xf;
-            rn = (insn >> 16) & 0xf;
-            tmp = load_reg(s, rm);
-            tmp2 = load_reg(s, rn);
-            if (op1 & 2)
-                gen_helper_double_saturate(tmp2, cpu_env, tmp2);
-            if (op1 & 1)
-                gen_helper_sub_saturate(tmp, cpu_env, tmp, tmp2);
-            else
-                gen_helper_add_saturate(tmp, cpu_env, tmp, tmp2);
-            tcg_temp_free_i32(tmp2);
-            store_reg(s, rd, tmp);
-            break;
+        case 0x5:
+            /* Saturating addition and subtraction.  */
+            /* All done in decodetree.  Reach here for illegal ops.  */
+            goto illegal_op;
         case 0x6: /* ERET */
             if (op1 != 3) {
                 goto illegal_op;
@@ -10070,18 +10100,8 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
             op = ((insn >> 17) & 0x38) | ((insn >> 4) & 7);
             if (op < 4) {
                 /* Saturating add/subtract.  */
-                if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
-                    goto illegal_op;
-                }
-                tmp = load_reg(s, rn);
-                tmp2 = load_reg(s, rm);
-                if (op & 1)
-                    gen_helper_double_saturate(tmp, cpu_env, tmp);
-                if (op & 2)
-                    gen_helper_sub_saturate(tmp, cpu_env, tmp2, tmp);
-                else
-                    gen_helper_add_saturate(tmp, cpu_env, tmp, tmp2);
-                tcg_temp_free_i32(tmp2);
+                /* All done in decodetree.  Reach here for illegal ops.  */
+                goto illegal_op;
             } else {
                 switch (op) {
                 case 0x0a: /* rbit */
diff --git a/target/arm/a32.decode b/target/arm/a32.decode
index 71846b79fd..af6712a9e8 100644
--- a/target/arm/a32.decode
+++ b/target/arm/a32.decode
@@ -27,6 +27,7 @@
 &s_rri_rot       s rn rd imm rot
 &s_rrrr          s rd rn rm ra
 &rrrr            rd rn rm ra
+&rrr             rd rn rm
 
 # Data-processing (register)
 
@@ -122,3 +123,12 @@ UMULL            .... 0000 100 . .... .... .... 1001 ....     @s_rdamn
 UMLAL            .... 0000 101 . .... .... .... 1001 ....     @s_rdamn
 SMULL            .... 0000 110 . .... .... .... 1001 ....     @s_rdamn
 SMLAL            .... 0000 111 . .... .... .... 1001 ....     @s_rdamn
+
+# Saturating addition and subtraction
+
+@rndm            ---- .... .... rn:4 rd:4 .... .... rm:4      &rrr
+
+QADD             .... 0001 0000 .... .... 0000 0101 ....      @rndm
+QSUB             .... 0001 0010 .... .... 0000 0101 ....      @rndm
+QDADD            .... 0001 0100 .... .... 0000 0101 ....      @rndm
+QDSUB            .... 0001 0110 .... .... 0000 0101 ....      @rndm
diff --git a/target/arm/t32.decode b/target/arm/t32.decode
index 8e301ed2a1..7a27b5cc5c 100644
--- a/target/arm/t32.decode
+++ b/target/arm/t32.decode
@@ -24,6 +24,7 @@
 &s_rri_rot       !extern s rn rd imm rot
 &s_rrrr          !extern s rd rn rm ra
 &rrrr            !extern rd rn rm ra
+&rrr             !extern rd rn rm
 
 # Data-processing (register-shifted register)
 
@@ -117,6 +118,7 @@ RSB_rri          1111 0.0 1110 . .... 0 ... .... ........     @s_rri_rot
 @s0_rnadm        .... .... .... rn:4 ra:4 rd:4 .... rm:4      &s_rrrr s=0
 @s0_rn0dm        .... .... .... rn:4 .... rd:4 .... rm:4      &s_rrrr ra=0 s=0
 @rnadm           .... .... .... rn:4 ra:4 rd:4 .... rm:4      &rrrr
+@rndm            .... .... .... rn:4 .... rd:4 .... rm:4      &rrr
 
 {
   MUL            1111 1011 0000 .... 1111 .... 0000 ....      @s0_rn0dm
@@ -128,3 +130,10 @@ UMULL            1111 1011 1010 .... .... .... 0000 ....      @s0_rnadm
 SMLAL            1111 1011 1100 .... .... .... 0000 ....      @s0_rnadm
 UMLAL            1111 1011 1110 .... .... .... 0000 ....      @s0_rnadm
 UMAAL            1111 1011 1110 .... .... .... 0110 ....      @rnadm
+
+# Data-processing (two source registers)
+
+QADD             1111 1010 1000 .... 1111 .... 1000 ....      @rndm
+QSUB             1111 1010 1000 .... 1111 .... 1010 ....      @rndm
+QDADD            1111 1010 1000 .... 1111 .... 1001 ....      @rndm
+QDSUB            1111 1010 1000 .... 1111 .... 1011 ....      @rndm
-- 
2.17.1