tcg/s390x: Support 128-bit load/store

Use LPQ/STPQ when 16-byte atomicity is required.
Note that these instructions require 16-byte alignment.

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

tcg/s390x/tcg-target-con-set.h

@@ -14,6 +14,7 @@ C_O0_I2(r, r)
 C_O0_I2(r, ri)
 C_O0_I2(r, rA)
 C_O0_I2(v, r)
+C_O0_I3(o, m, r)
 C_O1_I1(r, r)
 C_O1_I1(v, r)
 C_O1_I1(v, v)
@@ -36,6 +37,7 @@ C_O1_I2(v, v, v)
 C_O1_I3(v, v, v, v)
 C_O1_I4(r, r, ri, rI, r)
 C_O1_I4(r, r, rA, rI, r)
+C_O2_I1(o, m, r)
 C_O2_I2(o, m, 0, r)
 C_O2_I2(o, m, r, r)
 C_O2_I3(o, m, 0, 1, r)

tcg/s390x/tcg-target.c.inc

@@ -243,6 +243,7 @@ typedef enum S390Opcode {
     RXY_LLGF    = 0xe316,
     RXY_LLGH    = 0xe391,
     RXY_LMG     = 0xeb04,
+    RXY_LPQ     = 0xe38f,
     RXY_LRV     = 0xe31e,
     RXY_LRVG    = 0xe30f,
     RXY_LRVH    = 0xe31f,
@@ -253,6 +254,7 @@ typedef enum S390Opcode {
     RXY_STG     = 0xe324,
     RXY_STHY    = 0xe370,
     RXY_STMG    = 0xeb24,
+    RXY_STPQ    = 0xe38e,
     RXY_STRV    = 0xe33e,
     RXY_STRVG   = 0xe32f,
     RXY_STRVH   = 0xe33f,
@@ -1577,7 +1579,18 @@ typedef struct {
 
 bool tcg_target_has_memory_bswap(MemOp memop)
 {
-    return true;
+    TCGAtomAlign aa;
+
+    if ((memop & MO_SIZE) <= MO_64) {
+        return true;
+    }
+
+    /*
+     * Reject 16-byte memop with 16-byte atomicity,
+     * but do allow a pair of 64-bit operations.
+     */
+    aa = atom_and_align_for_opc(tcg_ctx, memop, MO_ATOM_IFALIGN, true);
+    return aa.atom <= MO_64;
 }
 
 static void tcg_out_qemu_ld_direct(TCGContext *s, MemOp opc, TCGReg data,
@@ -1734,13 +1747,13 @@ static TCGLabelQemuLdst *prepare_host_addr(TCGContext *s, HostAddress *h,
 {
     TCGLabelQemuLdst *ldst = NULL;
     MemOp opc = get_memop(oi);
+    MemOp s_bits = opc & MO_SIZE;
     unsigned a_mask;
 
-    h->aa = atom_and_align_for_opc(s, opc, MO_ATOM_IFALIGN, false);
+    h->aa = atom_and_align_for_opc(s, opc, MO_ATOM_IFALIGN, s_bits == MO_128);
     a_mask = (1 << h->aa.align) - 1;
 
 #ifdef CONFIG_SOFTMMU
-    unsigned s_bits = opc & MO_SIZE;
     unsigned s_mask = (1 << s_bits) - 1;
     int mem_index = get_mmuidx(oi);
     int fast_off = TLB_MASK_TABLE_OFS(mem_index);
@@ -1865,6 +1878,80 @@ static void tcg_out_qemu_st(TCGContext* s, TCGReg data_reg, TCGReg addr_reg,
     }
 }
 
+static void tcg_out_qemu_ldst_i128(TCGContext *s, TCGReg datalo, TCGReg datahi,
+                                   TCGReg addr_reg, MemOpIdx oi, bool is_ld)
+{
+    TCGLabel *l1 = NULL, *l2 = NULL;
+    TCGLabelQemuLdst *ldst;
+    HostAddress h;
+    bool need_bswap;
+    bool use_pair;
+    S390Opcode insn;
+
+    ldst = prepare_host_addr(s, &h, addr_reg, oi, is_ld);
+
+    use_pair = h.aa.atom < MO_128;
+    need_bswap = get_memop(oi) & MO_BSWAP;
+
+    if (!use_pair) {
+        /*
+         * Atomicity requires we use LPQ.  If we've already checked for
+         * 16-byte alignment, that's all we need.  If we arrive with
+         * lesser alignment, we have determined that less than 16-byte
+         * alignment can be satisfied with two 8-byte loads.
+         */
+        if (h.aa.align < MO_128) {
+            use_pair = true;
+            l1 = gen_new_label();
+            l2 = gen_new_label();
+
+            tcg_out_insn(s, RI, TMLL, addr_reg, 15);
+            tgen_branch(s, 7, l1); /* CC in {1,2,3} */
+        }
+
+        tcg_debug_assert(!need_bswap);
+        tcg_debug_assert(datalo & 1);
+        tcg_debug_assert(datahi == datalo - 1);
+        insn = is_ld ? RXY_LPQ : RXY_STPQ;
+        tcg_out_insn_RXY(s, insn, datahi, h.base, h.index, h.disp);
+
+        if (use_pair) {
+            tgen_branch(s, S390_CC_ALWAYS, l2);
+            tcg_out_label(s, l1);
+        }
+    }
+    if (use_pair) {
+        TCGReg d1, d2;
+
+        if (need_bswap) {
+            d1 = datalo, d2 = datahi;
+            insn = is_ld ? RXY_LRVG : RXY_STRVG;
+        } else {
+            d1 = datahi, d2 = datalo;
+            insn = is_ld ? RXY_LG : RXY_STG;
+        }
+
+        if (h.base == d1 || h.index == d1) {
+            tcg_out_insn(s, RXY, LAY, TCG_TMP0, h.base, h.index, h.disp);
+            h.base = TCG_TMP0;
+            h.index = TCG_REG_NONE;
+            h.disp = 0;
+        }
+        tcg_out_insn_RXY(s, insn, d1, h.base, h.index, h.disp);
+        tcg_out_insn_RXY(s, insn, d2, h.base, h.index, h.disp + 8);
+    }
+    if (l2) {
+        tcg_out_label(s, l2);
+    }
+
+    if (ldst) {
+        ldst->type = TCG_TYPE_I128;
+        ldst->datalo_reg = datalo;
+        ldst->datahi_reg = datahi;
+        ldst->raddr = tcg_splitwx_to_rx(s->code_ptr);
+    }
+}
+
 static void tcg_out_exit_tb(TCGContext *s, uintptr_t a0)
 {
     /* Reuse the zeroing that exists for goto_ptr.  */
@@ -2222,6 +2309,12 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
     case INDEX_op_qemu_st_i64:
         tcg_out_qemu_st(s, args[0], args[1], args[2], TCG_TYPE_I64);
         break;
+    case INDEX_op_qemu_ld_i128:
+        tcg_out_qemu_ldst_i128(s, args[0], args[1], args[2], args[3], true);
+        break;
+    case INDEX_op_qemu_st_i128:
+        tcg_out_qemu_ldst_i128(s, args[0], args[1], args[2], args[3], false);
+        break;
 
     case INDEX_op_ld16s_i64:
         tcg_out_mem(s, 0, RXY_LGH, args[0], args[1], TCG_REG_NONE, args[2]);
@@ -3099,6 +3192,10 @@ static TCGConstraintSetIndex tcg_target_op_def(TCGOpcode op)
     case INDEX_op_qemu_st_i64:
     case INDEX_op_qemu_st_i32:
         return C_O0_I2(r, r);
+    case INDEX_op_qemu_ld_i128:
+        return C_O2_I1(o, m, r);
+    case INDEX_op_qemu_st_i128:
+        return C_O0_I3(o, m, r);
 
     case INDEX_op_deposit_i32:
     case INDEX_op_deposit_i64:

tcg/s390x/tcg-target.h

@@ -140,7 +140,7 @@ extern uint64_t s390_facilities[3];
 #define TCG_TARGET_HAS_muluh_i64      0
 #define TCG_TARGET_HAS_mulsh_i64      0
 
-#define TCG_TARGET_HAS_qemu_ldst_i128 0
+#define TCG_TARGET_HAS_qemu_ldst_i128 1
 
 #define TCG_TARGET_HAS_v64            HAVE_FACILITY(VECTOR)
 #define TCG_TARGET_HAS_v128           HAVE_FACILITY(VECTOR)