target/arm: Simplify do_reduction_op

Use simple shift and add instead of ctpop, ctz, shift and mask.
Unlike SVE, there is no predicate to disable elements.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240912024114.1097832-10-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 13 insertions, 27 deletions

diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
index 04160b2..74efb35 100644
--- a/target/arm/tcg/translate-a64.c
+++ b/target/arm/tcg/translate-a64.c
@@ -9027,34 +9027,23 @@ static void disas_data_proc_fp(DisasContext *s, uint32_t insn)
  * important for correct NaN propagation that we do these
  * operations in exactly the order specified by the pseudocode.
  *
- * This is a recursive function, TCG temps should be freed by the
- * calling function once it is done with the values.
+ * This is a recursive function.
  */
 static TCGv_i32 do_reduction_op(DisasContext *s, int fpopcode, int rn,
-                                int esize, int size, int vmap, TCGv_ptr fpst)
+                                MemOp esz, int ebase, int ecount, TCGv_ptr fpst)
 {
-    if (esize == size) {
-        int element;
-        MemOp msize = esize == 16 ? MO_16 : MO_32;
-        TCGv_i32 tcg_elem;
-
-        /* We should have one register left here */
-        assert(ctpop8(vmap) == 1);
-        element = ctz32(vmap);
-        assert(element < 8);
-
-        tcg_elem = tcg_temp_new_i32();
-        read_vec_element_i32(s, tcg_elem, rn, element, msize);
+    if (ecount == 1) {
+        TCGv_i32 tcg_elem = tcg_temp_new_i32();
+        read_vec_element_i32(s, tcg_elem, rn, ebase, esz);
         return tcg_elem;
     } else {
-        int bits = size / 2;
-        int shift = ctpop8(vmap) / 2;
-        int vmap_lo = (vmap >> shift) & vmap;
-        int vmap_hi = (vmap & ~vmap_lo);
+        int half = ecount >> 1;
         TCGv_i32 tcg_hi, tcg_lo, tcg_res;
 
-        tcg_hi = do_reduction_op(s, fpopcode, rn, esize, bits, vmap_hi, fpst);
-        tcg_lo = do_reduction_op(s, fpopcode, rn, esize, bits, vmap_lo, fpst);
+        tcg_hi = do_reduction_op(s, fpopcode, rn, esz,
+                                 ebase + half, half, fpst);
+        tcg_lo = do_reduction_op(s, fpopcode, rn, esz,
+                                 ebase, half, fpst);
         tcg_res = tcg_temp_new_i32();
 
         switch (fpopcode) {
@@ -9105,7 +9094,6 @@ static void disas_simd_across_lanes(DisasContext *s, uint32_t insn)
     bool is_u = extract32(insn, 29, 1);
     bool is_fp = false;
     bool is_min = false;
-    int esize;
     int elements;
     int i;
     TCGv_i64 tcg_res, tcg_elt;
@@ -9152,8 +9140,7 @@ static void disas_simd_across_lanes(DisasContext *s, uint32_t insn)
         return;
     }
 
-    esize = 8 << size;
-    elements = (is_q ? 128 : 64) / esize;
+    elements = (is_q ? 16 : 8) >> size;
 
     tcg_res = tcg_temp_new_i64();
     tcg_elt = tcg_temp_new_i64();
@@ -9208,9 +9195,8 @@ static void disas_simd_across_lanes(DisasContext *s, uint32_t insn)
          */
         TCGv_ptr fpst = fpstatus_ptr(size == MO_16 ? FPST_FPCR_F16 : FPST_FPCR);
         int fpopcode = opcode | is_min << 4 | is_u << 5;
-        int vmap = (1 << elements) - 1;
-        TCGv_i32 tcg_res32 = do_reduction_op(s, fpopcode, rn, esize,
-                                             (is_q ? 128 : 64), vmap, fpst);
+        TCGv_i32 tcg_res32 = do_reduction_op(s, fpopcode, rn, size,
+                                             0, elements, fpst);
         tcg_gen_extu_i32_i64(tcg_res, tcg_res32);
     }