tcg/riscv: Fix base register for user-only qemu_ld/st

When guest_base != 0, we were not coordinating the usage of
TCG_REG_TMP0 as base properly, leading to a previous zero-extend
of the input address being discarded.

Shuffle the alignment check to the front, because that does not
depend on the zero-extend, and it keeps the register usage clear.
Set base after each step of the address arithmetic instead of before.

Return the base register used from tcg_out_tlb_load, so as to
keep that register choice localized to that function.

Reported-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20221023233337.2846860-1-richard.henderson@linaro.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 22 insertions, 17 deletions

diff --git a/tcg/riscv/tcg-target.c.inc b/tcg/riscv/tcg-target.c.inc
index 2a84c57..e3b6080 100644
--- a/tcg/riscv/tcg-target.c.inc
+++ b/tcg/riscv/tcg-target.c.inc
@@ -923,9 +923,9 @@ static void tcg_out_goto(TCGContext *s, const tcg_insn_unit *target)
     tcg_debug_assert(ok);
 }
 
-static void tcg_out_tlb_load(TCGContext *s, TCGReg addrl,
-                             TCGReg addrh, MemOpIdx oi,
-                             tcg_insn_unit **label_ptr, bool is_load)
+static TCGReg tcg_out_tlb_load(TCGContext *s, TCGReg addrl,
+                               TCGReg addrh, MemOpIdx oi,
+                               tcg_insn_unit **label_ptr, bool is_load)
 {
     MemOp opc = get_memop(oi);
     unsigned s_bits = opc & MO_SIZE;
@@ -975,6 +975,7 @@ static void tcg_out_tlb_load(TCGContext *s, TCGReg addrl,
         addrl = TCG_REG_TMP0;
     }
     tcg_out_opc_reg(s, OPC_ADD, TCG_REG_TMP0, TCG_REG_TMP2, addrl);
+    return TCG_REG_TMP0;
 }
 
 static void add_qemu_ldst_label(TCGContext *s, int is_ld, MemOpIdx oi,
@@ -1177,7 +1178,7 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, bool is_64)
 #else
     unsigned a_bits;
 #endif
-    TCGReg base = TCG_REG_TMP0;
+    TCGReg base;
 
     data_regl = *args++;
     data_regh = (TCG_TARGET_REG_BITS == 32 && is_64 ? *args++ : 0);
@@ -1187,23 +1188,25 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, bool is_64)
     opc = get_memop(oi);
 
 #if defined(CONFIG_SOFTMMU)
-    tcg_out_tlb_load(s, addr_regl, addr_regh, oi, label_ptr, 1);
+    base = 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);
     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;
-    }
     a_bits = get_alignment_bits(opc);
     if (a_bits) {
         tcg_out_test_alignment(s, true, addr_regl, a_bits);
     }
+    base = addr_regl;
+    if (TCG_TARGET_REG_BITS > TARGET_LONG_BITS) {
+        tcg_out_ext32u(s, TCG_REG_TMP0, base);
+        base = TCG_REG_TMP0;
+    }
     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, TCG_REG_TMP0, TCG_GUEST_BASE_REG, base);
+        base = TCG_REG_TMP0;
     }
     tcg_out_qemu_ld_direct(s, data_regl, data_regh, base, opc, is_64);
 #endif
@@ -1249,7 +1252,7 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, bool is_64)
 #else
     unsigned a_bits;
 #endif
-    TCGReg base = TCG_REG_TMP0;
+    TCGReg base;
 
     data_regl = *args++;
     data_regh = (TCG_TARGET_REG_BITS == 32 && is_64 ? *args++ : 0);
@@ -1259,23 +1262,25 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, bool is_64)
     opc = get_memop(oi);
 
 #if defined(CONFIG_SOFTMMU)
-    tcg_out_tlb_load(s, addr_regl, addr_regh, oi, label_ptr, 0);
+    base = 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);
     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;
-    }
     a_bits = get_alignment_bits(opc);
     if (a_bits) {
         tcg_out_test_alignment(s, false, addr_regl, a_bits);
     }
+    base = addr_regl;
+    if (TCG_TARGET_REG_BITS > TARGET_LONG_BITS) {
+        tcg_out_ext32u(s, TCG_REG_TMP0, base);
+        base = TCG_REG_TMP0;
+    }
     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, TCG_REG_TMP0, TCG_GUEST_BASE_REG, base);
+        base = TCG_REG_TMP0;
     }
     tcg_out_qemu_st_direct(s, data_regl, data_regh, base, opc);
 #endif