tcg: Add generic helpers for saturating arithmetic

No vector ops as yet.  SSE only has direct support for 8- and 16-bit
saturation; handling 32- and 64-bit saturation is much more expensive.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

2 files changed, 102 insertions, 0 deletions

diff --git a/tcg/tcg-op-gvec.c b/tcg/tcg-op-gvec.c
index 49c77e31aa..843bb5b166 100644
--- a/tcg/tcg-op-gvec.c
+++ b/tcg/tcg-op-gvec.c
@@ -1309,6 +1309,98 @@ void tcg_gen_gvec_mul(unsigned vece, uint32_t dofs, uint32_t aofs,
     tcg_gen_gvec_3(dofs, aofs, bofs, oprsz, maxsz, &g[vece]);
 }
 
+void tcg_gen_gvec_ssadd(unsigned vece, uint32_t dofs, uint32_t aofs,
+                        uint32_t bofs, uint32_t oprsz, uint32_t maxsz)
+{
+    static const GVecGen3 g[4] = {
+        { .fno = gen_helper_gvec_ssadd8, .vece = MO_8 },
+        { .fno = gen_helper_gvec_ssadd16, .vece = MO_16 },
+        { .fno = gen_helper_gvec_ssadd32, .vece = MO_32 },
+        { .fno = gen_helper_gvec_ssadd64, .vece = MO_64 }
+    };
+    tcg_debug_assert(vece <= MO_64);
+    tcg_gen_gvec_3(dofs, aofs, bofs, oprsz, maxsz, &g[vece]);
+}
+
+void tcg_gen_gvec_sssub(unsigned vece, uint32_t dofs, uint32_t aofs,
+                        uint32_t bofs, uint32_t oprsz, uint32_t maxsz)
+{
+    static const GVecGen3 g[4] = {
+        { .fno = gen_helper_gvec_sssub8, .vece = MO_8 },
+        { .fno = gen_helper_gvec_sssub16, .vece = MO_16 },
+        { .fno = gen_helper_gvec_sssub32, .vece = MO_32 },
+        { .fno = gen_helper_gvec_sssub64, .vece = MO_64 }
+    };
+    tcg_debug_assert(vece <= MO_64);
+    tcg_gen_gvec_3(dofs, aofs, bofs, oprsz, maxsz, &g[vece]);
+}
+
+static void tcg_gen_vec_usadd32_i32(TCGv_i32 d, TCGv_i32 a, TCGv_i32 b)
+{
+    TCGv_i32 max = tcg_const_i32(-1);
+    tcg_gen_add_i32(d, a, b);
+    tcg_gen_movcond_i32(TCG_COND_LTU, d, d, a, max, d);
+    tcg_temp_free_i32(max);
+}
+
+static void tcg_gen_vec_usadd32_i64(TCGv_i64 d, TCGv_i64 a, TCGv_i64 b)
+{
+    TCGv_i64 max = tcg_const_i64(-1);
+    tcg_gen_add_i64(d, a, b);
+    tcg_gen_movcond_i64(TCG_COND_LTU, d, d, a, max, d);
+    tcg_temp_free_i64(max);
+}
+
+void tcg_gen_gvec_usadd(unsigned vece, uint32_t dofs, uint32_t aofs,
+                        uint32_t bofs, uint32_t oprsz, uint32_t maxsz)
+{
+    static const GVecGen3 g[4] = {
+        { .fno = gen_helper_gvec_usadd8, .vece = MO_8 },
+        { .fno = gen_helper_gvec_usadd16, .vece = MO_16 },
+        { .fni4 = tcg_gen_vec_usadd32_i32,
+          .fno = gen_helper_gvec_usadd32,
+          .vece = MO_32 },
+        { .fni8 = tcg_gen_vec_usadd32_i64,
+          .fno = gen_helper_gvec_usadd64,
+          .vece = MO_64 }
+    };
+    tcg_debug_assert(vece <= MO_64);
+    tcg_gen_gvec_3(dofs, aofs, bofs, oprsz, maxsz, &g[vece]);
+}
+
+static void tcg_gen_vec_ussub32_i32(TCGv_i32 d, TCGv_i32 a, TCGv_i32 b)
+{
+    TCGv_i32 min = tcg_const_i32(0);
+    tcg_gen_sub_i32(d, a, b);
+    tcg_gen_movcond_i32(TCG_COND_LTU, d, a, b, min, d);
+    tcg_temp_free_i32(min);
+}
+
+static void tcg_gen_vec_ussub32_i64(TCGv_i64 d, TCGv_i64 a, TCGv_i64 b)
+{
+    TCGv_i64 min = tcg_const_i64(0);
+    tcg_gen_sub_i64(d, a, b);
+    tcg_gen_movcond_i64(TCG_COND_LTU, d, a, b, min, d);
+    tcg_temp_free_i64(min);
+}
+
+void tcg_gen_gvec_ussub(unsigned vece, uint32_t dofs, uint32_t aofs,
+                        uint32_t bofs, uint32_t oprsz, uint32_t maxsz)
+{
+    static const GVecGen3 g[4] = {
+        { .fno = gen_helper_gvec_ussub8, .vece = MO_8 },
+        { .fno = gen_helper_gvec_ussub16, .vece = MO_16 },
+        { .fni4 = tcg_gen_vec_ussub32_i32,
+          .fno = gen_helper_gvec_ussub32,
+          .vece = MO_32 },
+        { .fni8 = tcg_gen_vec_ussub32_i64,
+          .fno = gen_helper_gvec_ussub64,
+          .vece = MO_64 }
+    };
+    tcg_debug_assert(vece <= MO_64);
+    tcg_gen_gvec_3(dofs, aofs, bofs, oprsz, maxsz, &g[vece]);
+}
+
 /* Perform a vector negation using normal negation and a mask.
    Compare gen_subv_mask above.  */
 static void gen_negv_mask(TCGv_i64 d, TCGv_i64 b, TCGv_i64 m)
diff --git a/tcg/tcg-op-gvec.h b/tcg/tcg-op-gvec.h
index abe909df39..03ced440c2 100644
--- a/tcg/tcg-op-gvec.h
+++ b/tcg/tcg-op-gvec.h
@@ -179,6 +179,16 @@ void tcg_gen_gvec_sub(unsigned vece, uint32_t dofs, uint32_t aofs,
 void tcg_gen_gvec_mul(unsigned vece, uint32_t dofs, uint32_t aofs,
                       uint32_t bofs, uint32_t oprsz, uint32_t maxsz);
 
+/* Saturated arithmetic.  */
+void tcg_gen_gvec_ssadd(unsigned vece, uint32_t dofs, uint32_t aofs,
+                        uint32_t bofs, uint32_t oprsz, uint32_t maxsz);
+void tcg_gen_gvec_sssub(unsigned vece, uint32_t dofs, uint32_t aofs,
+                        uint32_t bofs, uint32_t oprsz, uint32_t maxsz);
+void tcg_gen_gvec_usadd(unsigned vece, uint32_t dofs, uint32_t aofs,
+                        uint32_t bofs, uint32_t oprsz, uint32_t maxsz);
+void tcg_gen_gvec_ussub(unsigned vece, uint32_t dofs, uint32_t aofs,
+                        uint32_t bofs, uint32_t oprsz, uint32_t maxsz);
+
 void tcg_gen_gvec_and(unsigned vece, uint32_t dofs, uint32_t aofs,
                       uint32_t bofs, uint32_t oprsz, uint32_t maxsz);
 void tcg_gen_gvec_or(unsigned vece, uint32_t dofs, uint32_t aofs,