[PULL,05/10] tcg/mips: Unset TCG_TARGET_HAS_direct_jump

Commit Message

Richard Henderson Sept. 21, 2021, 2:25 a.m. UTC

Only use indirect jumps.  Finish weaning away from the
unique alignment requirements for code_gen_buffer.

Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>
Signed-off-by: Richard Henderson <[e-mail]>
---
 tcg/mips/tcg-target.h     | 12 +++++-------
 tcg/mips/tcg-target.c.inc | 23 +++++------------------
 2 files changed, 10 insertions(+), 25 deletions(-)

Patch

diff --git a/tcg/mips/tcg-target.h b/tcg/mips/tcg-target.h
index 3a62055f04..c366fdf74b 100644
--- a/tcg/mips/tcg-target.h
+++ b/tcg/mips/tcg-target.h
@@ -39,11 +39,7 @@ 
 #define TCG_TARGET_TLB_DISPLACEMENT_BITS 16
 #define TCG_TARGET_NB_REGS 32
 
-/*
- * We have a 256MB branch region, but leave room to make sure the
- * main executable is also within that region.
- */
-#define MAX_CODE_GEN_BUFFER_SIZE  (128 * MiB)
+#define MAX_CODE_GEN_BUFFER_SIZE  ((size_t)-1)
 
 typedef enum {
     TCG_REG_ZERO = 0,
@@ -136,7 +132,7 @@  extern bool use_mips32r2_instructions;
 #define TCG_TARGET_HAS_muluh_i32        1
 #define TCG_TARGET_HAS_mulsh_i32        1
 #define TCG_TARGET_HAS_bswap32_i32      1
-#define TCG_TARGET_HAS_direct_jump      1
+#define TCG_TARGET_HAS_direct_jump      0
 
 #if TCG_TARGET_REG_BITS == 64
 #define TCG_TARGET_HAS_add2_i32         0
@@ -207,7 +203,9 @@  extern bool use_mips32r2_instructions;
 #define TCG_TARGET_DEFAULT_MO (0)
 #define TCG_TARGET_HAS_MEMORY_BSWAP     1
 
-void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t);
+/* not defined -- call should be eliminated at compile time */
+void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t)
+    QEMU_ERROR("code path is reachable");
 
 #ifdef CONFIG_SOFTMMU
 #define TCG_TARGET_NEED_LDST_LABELS
diff --git a/tcg/mips/tcg-target.c.inc b/tcg/mips/tcg-target.c.inc
index 3a40af8799..41ffa28394 100644
--- a/tcg/mips/tcg-target.c.inc
+++ b/tcg/mips/tcg-target.c.inc
@@ -1654,17 +1654,11 @@  static void tcg_out_op(TCGContext *s, TCGOpcode opc,
         }
         break;
     case INDEX_op_goto_tb:
-        if (s->tb_jmp_insn_offset) {
-            /* direct jump method */
-            s->tb_jmp_insn_offset[a0] = tcg_current_code_size(s);
-            /* Avoid clobbering the address during retranslation.  */
-            tcg_out32(s, OPC_J | (*(uint32_t *)s->code_ptr & 0x3ffffff));
-        } else {
-            /* indirect jump method */
-            tcg_out_ld(s, TCG_TYPE_PTR, TCG_TMP0, TCG_REG_ZERO,
-                       (uintptr_t)(s->tb_jmp_target_addr + a0));
-            tcg_out_opc_reg(s, OPC_JR, 0, TCG_TMP0, 0);
-        }
+        /* indirect jump method */
+        tcg_debug_assert(s->tb_jmp_insn_offset == 0);
+        tcg_out_ld(s, TCG_TYPE_PTR, TCG_TMP0, TCG_REG_ZERO,
+                   (uintptr_t)(s->tb_jmp_target_addr + a0));
+        tcg_out_opc_reg(s, OPC_JR, 0, TCG_TMP0, 0);
         tcg_out_nop(s);
         set_jmp_reset_offset(s, a0);
         break;
@@ -2538,13 +2532,6 @@  static void tcg_target_init(TCGContext *s)
     tcg_regset_set_reg(s->reserved_regs, TCG_REG_GP);   /* global pointer */
 }
 
-void tb_target_set_jmp_target(uintptr_t tc_ptr, uintptr_t jmp_rx,
-                              uintptr_t jmp_rw, uintptr_t addr)
-{
-    qatomic_set((uint32_t *)jmp_rw, deposit32(OPC_J, 0, 26, addr >> 2));
-    flush_idcache_range(jmp_rx, jmp_rw, 4);
-}
-
 typedef struct {
     DebugFrameHeader h;
     uint8_t fde_def_cfa[4];