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[Qemu-devel] [PULL 03/24] tcg-mips: Use J and JAL opcodes
From: |
Richard Henderson |
Subject: |
[Qemu-devel] [PULL 03/24] tcg-mips: Use J and JAL opcodes |
Date: |
Sat, 24 May 2014 08:53:40 -0700 |
For userland builds calls will normally be in range,
and for the exit_tb opcode the branch to the epilogue.
Reviewed-by: Paolo Bonzini <address@hidden>
Signed-off-by: Richard Henderson <address@hidden>
---
tcg/mips/tcg-target.c | 46 ++++++++++++++++++++++++++++++++++++++++------
1 file changed, 40 insertions(+), 6 deletions(-)
diff --git a/tcg/mips/tcg-target.c b/tcg/mips/tcg-target.c
index 0ae495c..d4236c0 100644
--- a/tcg/mips/tcg-target.c
+++ b/tcg/mips/tcg-target.c
@@ -222,6 +222,8 @@ static inline int tcg_target_const_match(tcg_target_long
val, TCGType type,
/* instruction opcodes */
enum {
+ OPC_J = 0x02 << 26,
+ OPC_JAL = 0x03 << 26,
OPC_BEQ = 0x04 << 26,
OPC_BNE = 0x05 << 26,
OPC_BLEZ = 0x06 << 26,
@@ -345,6 +347,29 @@ static inline void tcg_out_opc_sa(TCGContext *s, int opc,
}
+/*
+ * Type jump.
+ * Returns true if the branch was in range and the insn was emitted.
+ */
+static bool tcg_out_opc_jmp(TCGContext *s, int opc, void *target)
+{
+ uintptr_t dest = (uintptr_t)target;
+ uintptr_t from = (uintptr_t)s->code_ptr + 4;
+ int32_t inst;
+
+ /* The pc-region branch happens within the 256MB region of
+ the delay slot (thus the +4). */
+ if ((from ^ dest) & -(1 << 28)) {
+ return false;
+ }
+ assert((dest & 3) == 0);
+
+ inst = opc;
+ inst |= (dest >> 2) & 0x3ffffff;
+ tcg_out32(s, inst);
+ return true;
+}
+
static inline void tcg_out_nop(TCGContext *s)
{
tcg_out32(s, 0);
@@ -1247,10 +1272,17 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg
*args,
#endif
}
-static void tcg_out_call(TCGContext *s, tcg_insn_unit *target)
+static void tcg_out_call(TCGContext *s, tcg_insn_unit *arg)
{
- tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_T9, (intptr_t)target);
- tcg_out_opc_reg(s, OPC_JALR, TCG_REG_RA, TCG_REG_T9, 0);
+ /* Note that the ABI requires the called function's address to be
+ loaded into T9, even if a direct branch is in range. */
+ tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_T9, (uintptr_t)arg);
+
+ /* But do try a direct branch, allowing the cpu better insn prefetch. */
+ if (!tcg_out_opc_jmp(s, OPC_JAL, arg)) {
+ tcg_out_opc_reg(s, OPC_JALR, TCG_REG_RA, TCG_REG_T9, 0);
+ }
+
tcg_out_nop(s);
}
@@ -1259,9 +1291,11 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode
opc,
{
switch(opc) {
case INDEX_op_exit_tb:
- tcg_out_movi(s, TCG_TYPE_I32, TCG_REG_V0, args[0]);
- tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_AT, (uintptr_t)tb_ret_addr);
- tcg_out_opc_reg(s, OPC_JR, 0, TCG_REG_AT, 0);
+ tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_V0, args[0]);
+ if (!tcg_out_opc_jmp(s, OPC_J, tb_ret_addr)) {
+ tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_AT, (uintptr_t)tb_ret_addr);
+ tcg_out_opc_reg(s, OPC_JR, 0, TCG_REG_AT, 0);
+ }
tcg_out_nop(s);
break;
case INDEX_op_goto_tb:
--
1.9.0
- [Qemu-devel] [PULL 00/24] tcg mips updates, Richard Henderson, 2014/05/24
- [Qemu-devel] [PULL 01/24] tcg-mips: Layout executable and code_gen_buffer, Richard Henderson, 2014/05/24
- [Qemu-devel] [PULL 03/24] tcg-mips: Use J and JAL opcodes,
Richard Henderson <=
- [Qemu-devel] [PULL 02/24] tcg-mips: Constrain the code_gen_buffer to be within one 256mb segment, Richard Henderson, 2014/05/24
- [Qemu-devel] [PULL 04/24] tcg-mips: Fill the exit_tb delay slot, Richard Henderson, 2014/05/24
- [Qemu-devel] [PULL 05/24] tcg-mips: Split large ldst offsets, Richard Henderson, 2014/05/24
- [Qemu-devel] [PULL 06/24] tcg-mips: Move softmmu slow path out of line, Richard Henderson, 2014/05/24
- [Qemu-devel] [PULL 07/24] tcg-mips: Convert to new qemu_l/st helpers, Richard Henderson, 2014/05/24
- [Qemu-devel] [PULL 08/24] tcg-mips: Convert to new_ldst, Richard Henderson, 2014/05/24
- [Qemu-devel] [PULL 09/24] tcg-mips: Rearrange register allocation, Richard Henderson, 2014/05/24
- [Qemu-devel] [PULL 10/24] tcg-mips: Introduce TCG_TMP0, TCG_TMP1, Richard Henderson, 2014/05/24
- [Qemu-devel] [PULL 11/24] tcg-mips: Use T9 for TCG_TMP1, Richard Henderson, 2014/05/24
- [Qemu-devel] [PULL 12/24] tcg-mips: Use EXT for AND on mips32r2, Richard Henderson, 2014/05/24