[PATCH 1/1] tcg/riscv: Fix base regsiter for qemu_ld/st

[PATCH 1/1] tcg/riscv: Fix base regsiter for qemu_ld/st

[LIU Zhiwei]

When guest base is zero, we should use addr_regl as base regiser instead of
the initial register TCG_REG_TMP0. Besides, we can remove the
unnecessary use of base register.

Signed-off-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
---
 tcg/riscv/tcg-target.c.inc | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/tcg/riscv/tcg-target.c.inc b/tcg/riscv/tcg-target.c.inc
index 81a83e45b1..946da1bb72 100644
--- a/tcg/riscv/tcg-target.c.inc
+++ b/tcg/riscv/tcg-target.c.inc
@@ -1158,7 +1158,6 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, bool is_64)
 #else
     unsigned a_bits;
 #endif
-    TCGReg base = TCG_REG_TMP0;
 
     data_regl = *args++;
     data_regh = (TCG_TARGET_REG_BITS == 32 && is_64 ? *args++ : 0);
@@ -1169,24 +1168,23 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, bool is_64)
 
 #if defined(CONFIG_SOFTMMU)
     tcg_out_tlb_load(s, addr_regl, addr_regh, oi, label_ptr, 1);
-    tcg_out_qemu_ld_direct(s, data_regl, data_regh, base, opc, is_64);
+    tcg_out_qemu_ld_direct(s, data_regl, data_regh, TCG_REG_TMP0, opc, is_64);
     add_qemu_ldst_label(s, 1, oi,
                         (is_64 ? TCG_TYPE_I64 : TCG_TYPE_I32),
                         data_regl, data_regh, addr_regl, addr_regh,
                         s->code_ptr, label_ptr);
 #else
     if (TCG_TARGET_REG_BITS > TARGET_LONG_BITS) {
-        tcg_out_ext32u(s, base, addr_regl);
-        addr_regl = base;
+        tcg_out_ext32u(s, addr_regl, addr_regl);
     }
     a_bits = get_alignment_bits(opc);
     if (a_bits) {
         tcg_out_test_alignment(s, true, addr_regl, a_bits);
     }
     if (guest_base != 0) {
-        tcg_out_opc_reg(s, OPC_ADD, base, TCG_GUEST_BASE_REG, addr_regl);
+        tcg_out_opc_reg(s, OPC_ADD, addr_regl, TCG_GUEST_BASE_REG, addr_regl);
     }
-    tcg_out_qemu_ld_direct(s, data_regl, data_regh, base, opc, is_64);
+    tcg_out_qemu_ld_direct(s, data_regl, data_regh, addr_regl, opc, is_64);
 #endif
 }
 
@@ -1230,7 +1228,6 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, bool is_64)
 #else
     unsigned a_bits;
 #endif
-    TCGReg base = TCG_REG_TMP0;
 
     data_regl = *args++;
     data_regh = (TCG_TARGET_REG_BITS == 32 && is_64 ? *args++ : 0);
@@ -1241,24 +1238,23 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, bool is_64)
 
 #if defined(CONFIG_SOFTMMU)
     tcg_out_tlb_load(s, addr_regl, addr_regh, oi, label_ptr, 0);
-    tcg_out_qemu_st_direct(s, data_regl, data_regh, base, opc);
+    tcg_out_qemu_st_direct(s, data_regl, data_regh, TCG_REG_TMP0, opc);
     add_qemu_ldst_label(s, 0, oi,
                         (is_64 ? TCG_TYPE_I64 : TCG_TYPE_I32),
                         data_regl, data_regh, addr_regl, addr_regh,
                         s->code_ptr, label_ptr);
 #else
     if (TCG_TARGET_REG_BITS > TARGET_LONG_BITS) {
-        tcg_out_ext32u(s, base, addr_regl);
-        addr_regl = base;
+        tcg_out_ext32u(s, addr_regl, addr_regl);
     }
     a_bits = get_alignment_bits(opc);
     if (a_bits) {
         tcg_out_test_alignment(s, false, addr_regl, a_bits);
     }
     if (guest_base != 0) {
-        tcg_out_opc_reg(s, OPC_ADD, base, TCG_GUEST_BASE_REG, addr_regl);
+        tcg_out_opc_reg(s, OPC_ADD, addr_regl, TCG_GUEST_BASE_REG, addr_regl);
     }
-    tcg_out_qemu_st_direct(s, data_regl, data_regh, base, opc);
+    tcg_out_qemu_st_direct(s, data_regl, data_regh, addr_regl, opc);
 #endif
 }
 
-- 
2.25.1

Re: [PATCH 1/1] tcg/riscv: Fix base regsiter for qemu_ld/st

[Richard Henderson]

On 10/23/22 22:41, LIU Zhiwei wrote:
>       if (TCG_TARGET_REG_BITS > TARGET_LONG_BITS) {
> -        tcg_out_ext32u(s, base, addr_regl);
> -        addr_regl = base;
> +        tcg_out_ext32u(s, addr_regl, addr_regl);
>       }

Incorrect.  You may not modify input registers.


r~