[Qemu-devel] [RFC v1 15/23] riscv: tcg-target: Add branch and jump instructions

[Alistair Francis]

Signed-off-by: Alistair Francis <address@hidden>
Signed-off-by: Michael Clark <address@hidden>
---
 tcg/riscv/tcg-target.inc.c | 144 +++++++++++++++++++++++++++++++++++++
 1 file changed, 144 insertions(+)

diff --git a/tcg/riscv/tcg-target.inc.c b/tcg/riscv/tcg-target.inc.c
index bc433170c4..b449e17295 100644
--- a/tcg/riscv/tcg-target.inc.c
+++ b/tcg/riscv/tcg-target.inc.c
@@ -574,6 +574,150 @@ static bool tcg_out_sti(TCGContext *s, TCGType type, 
TCGArg val,
     return false;
 }
 
+static const struct {
+    RISCVInsn op;
+    bool swap;
+} tcg_brcond_to_riscv[] = {
+    [TCG_COND_EQ] =  { OPC_BEQ,  false },
+    [TCG_COND_NE] =  { OPC_BNE,  false },
+    [TCG_COND_LT] =  { OPC_BLT,  false },
+    [TCG_COND_GE] =  { OPC_BGE,  false },
+    [TCG_COND_LE] =  { OPC_BGE,  true  },
+    [TCG_COND_GT] =  { OPC_BLT,  true  },
+    [TCG_COND_LTU] = { OPC_BLTU, false },
+    [TCG_COND_GEU] = { OPC_BGEU, false },
+    [TCG_COND_LEU] = { OPC_BGEU, true  },
+    [TCG_COND_GTU] = { OPC_BLTU, true  }
+};
+
+static void tcg_out_brcond(TCGContext *s, TCGCond cond, TCGReg arg1,
+                           TCGReg arg2, TCGLabel *l)
+{
+    RISCVInsn op = tcg_brcond_to_riscv[cond].op;
+    bool swap = tcg_brcond_to_riscv[cond].swap;
+
+    tcg_out_opc_branch(s, op, swap ? arg2 : arg1, swap ? arg1 : arg2, 0);
+
+    if (l->has_value) {
+        reloc_sbimm12(s->code_ptr - 1, l->u.value_ptr);
+    } else {
+        tcg_out_reloc(s, s->code_ptr - 1, R_RISCV_BRANCH, l, 0);
+    }
+}
+
+static void tcg_out_setcond(TCGContext *s, TCGCond cond, TCGReg ret,
+                            TCGReg arg1, TCGReg arg2)
+{
+    switch (cond) {
+    case TCG_COND_EQ:
+        tcg_out_opc_reg(s, OPC_SUB, ret, arg1, arg2);
+        tcg_out_opc_imm(s, OPC_SLTIU, ret, ret, 1);
+        break;
+    case TCG_COND_NE:
+        tcg_out_opc_reg(s, OPC_SUB, ret, arg1, arg2);
+        tcg_out_opc_reg(s, OPC_SLTU, ret, TCG_REG_ZERO, ret);
+        break;
+    case TCG_COND_LT:
+        tcg_out_opc_reg(s, OPC_SLT, ret, arg1, arg2);
+        break;
+    case TCG_COND_GE:
+        tcg_out_opc_reg(s, OPC_SLT, ret, arg1, arg2);
+        tcg_out_opc_imm(s, OPC_XORI, ret, ret, 1);
+        break;
+    case TCG_COND_LE:
+        tcg_out_opc_reg(s, OPC_SLT, ret, arg2, arg1);
+        tcg_out_opc_imm(s, OPC_XORI, ret, ret, 1);
+        break;
+    case TCG_COND_GT:
+        tcg_out_opc_reg(s, OPC_SLT, ret, arg2, arg1);
+        break;
+    case TCG_COND_LTU:
+        tcg_out_opc_reg(s, OPC_SLTU, ret, arg1, arg2);
+        break;
+    case TCG_COND_GEU:
+        tcg_out_opc_reg(s, OPC_SLTU, ret, arg1, arg2);
+        tcg_out_opc_imm(s, OPC_XORI, ret, ret, 1);
+        break;
+    case TCG_COND_LEU:
+        tcg_out_opc_reg(s, OPC_SLTU, ret, arg2, arg1);
+        tcg_out_opc_imm(s, OPC_XORI, ret, ret, 1);
+        break;
+    case TCG_COND_GTU:
+        tcg_out_opc_reg(s, OPC_SLTU, ret, arg2, arg1);
+        break;
+    default:
+         g_assert_not_reached();
+         break;
+     }
+}
+
+static void tcg_out_brcond2(TCGContext *s, TCGCond cond, TCGReg al, TCGReg ah,
+                            TCGReg bl, TCGReg bh, TCGLabel *l)
+{
+    /* todo */
+    g_assert_not_reached();
+}
+
+static void tcg_out_setcond2(TCGContext *s, TCGCond cond, TCGReg ret,
+                             TCGReg al, TCGReg ah, TCGReg bl, TCGReg bh)
+{
+    /* todo */
+    g_assert_not_reached();
+}
+
+static inline void tcg_out_goto(TCGContext *s, tcg_insn_unit *target)
+{
+    ptrdiff_t offset = tcg_pcrel_diff(s, target);
+    tcg_debug_assert(offset == sextract64(offset, 0, 26));
+    tcg_out_opc_jump(s, OPC_JAL, TCG_REG_ZERO, offset);
+}
+
+static inline void tcg_out_goto_long(TCGContext *s, tcg_insn_unit *target)
+{
+    ptrdiff_t offset = tcg_pcrel_diff(s, target);
+
+    if (offset == sextract64(offset, 0, 26)) {
+        tcg_out_opc_jump(s, OPC_JAL, TCG_REG_ZERO, offset);
+    } else {
+        tcg_out_movi(s, TCG_TYPE_I64, TCG_REG_TMP0, (intptr_t)target);
+        tcg_out_opc_jump(s, OPC_JAL, TCG_REG_TMP0, 0);
+    }
+}
+
+static void tcg_out_call_int(TCGContext *s, tcg_insn_unit *arg, bool tail)
+{
+    TCGReg link = tail ? TCG_REG_ZERO : TCG_REG_RA;
+    ptrdiff_t offset = tcg_pcrel_diff(s, arg);
+    if (offset == sextract32(offset, 1, 20) << 1) {
+        /* short jump: -2097150 to 2097152 */
+        tcg_out_opc_jump(s, OPC_JAL, link, offset);
+    } else if (TCG_TARGET_REG_BITS == 32 ||
+        offset == sextract32(offset, 1, 31) << 1) {
+        /* long jump: -2147483646 to 2147483648 */
+        tcg_out_opc_upper(s, OPC_AUIPC, TCG_REG_TMP0, 0);
+        tcg_out_opc_imm(s, OPC_JALR, link, TCG_REG_TMP0, 0);
+        reloc_call(s->code_ptr - 2, arg);
+    } else if (TCG_TARGET_REG_BITS == 64) {
+        /* far jump: 64-bit */
+        tcg_target_long imm = sextract32((tcg_target_long)arg, 0, 12);
+        tcg_target_long base = (tcg_target_long)arg - imm;
+        tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_TMP0, base);
+        tcg_out_opc_imm(s, OPC_JALR, link, TCG_REG_TMP0, imm);
+    } else {
+        g_assert_not_reached();
+    }
+}
+
+static void tcg_out_tail(TCGContext *s, tcg_insn_unit *arg)
+{
+    tcg_out_call_int(s, arg, true);
+}
+
+static void tcg_out_call(TCGContext *s, tcg_insn_unit *arg)
+{
+    tcg_out_call_int(s, arg, false);
+}
+
 void tb_target_set_jmp_target(uintptr_t tc_ptr, uintptr_t jmp_addr,
                               uintptr_t addr)
 {
-- 
2.19.1