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[PATCH v2 3/4] target/arm: Use clear_vec_high more effectively


From: Richard Henderson
Subject: [PATCH v2 3/4] target/arm: Use clear_vec_high more effectively
Date: Thu, 7 May 2020 10:23:51 -0700

Do not explicitly store zero to the NEON high part
when we can pass !is_q to clear_vec_high.

Reviewed-by: Alex Bennée <address@hidden>
Signed-off-by: Richard Henderson <address@hidden>
---
 target/arm/translate-a64.c | 59 +++++++++++++++++++++++---------------
 1 file changed, 36 insertions(+), 23 deletions(-)

diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index b6feb2b9dc..0947eaee05 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -939,11 +939,10 @@ static void do_fp_ld(DisasContext *s, int destidx, 
TCGv_i64 tcg_addr, int size)
 {
     /* This always zero-extends and writes to a full 128 bit wide vector */
     TCGv_i64 tmplo = tcg_temp_new_i64();
-    TCGv_i64 tmphi;
+    TCGv_i64 tmphi = NULL;
 
     if (size < 4) {
         MemOp memop = s->be_data + size;
-        tmphi = tcg_const_i64(0);
         tcg_gen_qemu_ld_i64(tmplo, tcg_addr, get_mem_index(s), memop);
     } else {
         bool be = s->be_data == MO_BE;
@@ -961,12 +960,13 @@ static void do_fp_ld(DisasContext *s, int destidx, 
TCGv_i64 tcg_addr, int size)
     }
 
     tcg_gen_st_i64(tmplo, cpu_env, fp_reg_offset(s, destidx, MO_64));
-    tcg_gen_st_i64(tmphi, cpu_env, fp_reg_hi_offset(s, destidx));
-
     tcg_temp_free_i64(tmplo);
-    tcg_temp_free_i64(tmphi);
 
-    clear_vec_high(s, true, destidx);
+    if (tmphi) {
+        tcg_gen_st_i64(tmphi, cpu_env, fp_reg_hi_offset(s, destidx));
+        tcg_temp_free_i64(tmphi);
+    }
+    clear_vec_high(s, tmphi != NULL, destidx);
 }
 
 /*
@@ -6960,8 +6960,8 @@ static void disas_simd_ext(DisasContext *s, uint32_t insn)
         return;
     }
 
-    tcg_resh = tcg_temp_new_i64();
     tcg_resl = tcg_temp_new_i64();
+    tcg_resh = NULL;
 
     /* Vd gets bits starting at pos bits into Vm:Vn. This is
      * either extracting 128 bits from a 128:128 concatenation, or
@@ -6973,7 +6973,6 @@ static void disas_simd_ext(DisasContext *s, uint32_t insn)
             read_vec_element(s, tcg_resh, rm, 0, MO_64);
             do_ext64(s, tcg_resh, tcg_resl, pos);
         }
-        tcg_gen_movi_i64(tcg_resh, 0);
     } else {
         TCGv_i64 tcg_hh;
         typedef struct {
@@ -6988,6 +6987,7 @@ static void disas_simd_ext(DisasContext *s, uint32_t insn)
             pos -= 64;
         }
 
+        tcg_resh = tcg_temp_new_i64();
         read_vec_element(s, tcg_resl, elt->reg, elt->elt, MO_64);
         elt++;
         read_vec_element(s, tcg_resh, elt->reg, elt->elt, MO_64);
@@ -7003,9 +7003,12 @@ static void disas_simd_ext(DisasContext *s, uint32_t 
insn)
 
     write_vec_element(s, tcg_resl, rd, 0, MO_64);
     tcg_temp_free_i64(tcg_resl);
-    write_vec_element(s, tcg_resh, rd, 1, MO_64);
-    tcg_temp_free_i64(tcg_resh);
-    clear_vec_high(s, true, rd);
+
+    if (is_q) {
+        write_vec_element(s, tcg_resh, rd, 1, MO_64);
+        tcg_temp_free_i64(tcg_resh);
+    }
+    clear_vec_high(s, is_q, rd);
 }
 
 /* TBL/TBX
@@ -7042,17 +7045,21 @@ static void disas_simd_tb(DisasContext *s, uint32_t 
insn)
      * the input.
      */
     tcg_resl = tcg_temp_new_i64();
-    tcg_resh = tcg_temp_new_i64();
+    tcg_resh = NULL;
 
     if (is_tblx) {
         read_vec_element(s, tcg_resl, rd, 0, MO_64);
     } else {
         tcg_gen_movi_i64(tcg_resl, 0);
     }
-    if (is_tblx && is_q) {
-        read_vec_element(s, tcg_resh, rd, 1, MO_64);
-    } else {
-        tcg_gen_movi_i64(tcg_resh, 0);
+
+    if (is_q) {
+        tcg_resh = tcg_temp_new_i64();
+        if (is_tblx) {
+            read_vec_element(s, tcg_resh, rd, 1, MO_64);
+        } else {
+            tcg_gen_movi_i64(tcg_resh, 0);
+        }
     }
 
     tcg_idx = tcg_temp_new_i64();
@@ -7072,9 +7079,12 @@ static void disas_simd_tb(DisasContext *s, uint32_t insn)
 
     write_vec_element(s, tcg_resl, rd, 0, MO_64);
     tcg_temp_free_i64(tcg_resl);
-    write_vec_element(s, tcg_resh, rd, 1, MO_64);
-    tcg_temp_free_i64(tcg_resh);
-    clear_vec_high(s, true, rd);
+
+    if (is_q) {
+        write_vec_element(s, tcg_resh, rd, 1, MO_64);
+        tcg_temp_free_i64(tcg_resh);
+    }
+    clear_vec_high(s, is_q, rd);
 }
 
 /* ZIP/UZP/TRN
@@ -7111,7 +7121,7 @@ static void disas_simd_zip_trn(DisasContext *s, uint32_t 
insn)
     }
 
     tcg_resl = tcg_const_i64(0);
-    tcg_resh = tcg_const_i64(0);
+    tcg_resh = is_q ? tcg_const_i64(0) : NULL;
     tcg_res = tcg_temp_new_i64();
 
     for (i = 0; i < elements; i++) {
@@ -7162,9 +7172,12 @@ static void disas_simd_zip_trn(DisasContext *s, uint32_t 
insn)
 
     write_vec_element(s, tcg_resl, rd, 0, MO_64);
     tcg_temp_free_i64(tcg_resl);
-    write_vec_element(s, tcg_resh, rd, 1, MO_64);
-    tcg_temp_free_i64(tcg_resh);
-    clear_vec_high(s, true, rd);
+
+    if (is_q) {
+        write_vec_element(s, tcg_resh, rd, 1, MO_64);
+        tcg_temp_free_i64(tcg_resh);
+    }
+    clear_vec_high(s, is_q, rd);
 }
 
 /*
-- 
2.20.1




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