tcg: Move tcg prologue pointer out of TCGContext

This value is constant across all thread-local copies of TCGContext,
so we might as well move it out of thread-local storage.

Use the correct function pointer type, and name the variable
tcg_qemu_tb_exec, which means that we are able to remove the
macro that does the casting.

Replace HAVE_TCG_QEMU_TB_EXEC with CONFIG_TCG_INTERPRETER,
as this is somewhat clearer in intent.

Reviewed-by: Joelle van Dyne <j@getutm.app>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

include/tcg/tcg.h

@@ -621,7 +621,6 @@ struct TCGContext {
        here, because there's too much arithmetic throughout that relies
        on addition and subtraction working on bytes.  Rely on the GCC
        extension that allows arithmetic on void*.  */
-    void *code_gen_prologue;
     void *code_gen_epilogue;
     void *code_gen_buffer;
     size_t code_gen_buffer_size;
@@ -1222,11 +1221,11 @@ static inline unsigned get_mmuidx(TCGMemOpIdx oi)
 #define TB_EXIT_IDXMAX    1
 #define TB_EXIT_REQUESTED 3
 
-#ifdef HAVE_TCG_QEMU_TB_EXEC
-uintptr_t tcg_qemu_tb_exec(CPUArchState *env, uint8_t *tb_ptr);
+#ifdef CONFIG_TCG_INTERPRETER
+uintptr_t tcg_qemu_tb_exec(CPUArchState *env, void *tb_ptr);
 #else
-# define tcg_qemu_tb_exec(env, tb_ptr) \
-    ((uintptr_t (*)(void *, void *))tcg_ctx->code_gen_prologue)(env, tb_ptr)
+typedef uintptr_t tcg_prologue_fn(CPUArchState *env, void *tb_ptr);
+extern tcg_prologue_fn *tcg_qemu_tb_exec;
 #endif
 
 void tcg_register_jit(void *buf, size_t buf_size);

tcg/tcg.c

@@ -162,6 +162,10 @@ static TCGContext **tcg_ctxs;
 static unsigned int n_tcg_ctxs;
 TCGv_env cpu_env = 0;
 
+#ifndef CONFIG_TCG_INTERPRETER
+tcg_prologue_fn *tcg_qemu_tb_exec;
+#endif
+
 struct tcg_region_tree {
     QemuMutex lock;
     GTree *tree;
@@ -1055,7 +1059,10 @@ void tcg_prologue_init(TCGContext *s)
     s->code_ptr = buf0;
     s->code_buf = buf0;
     s->data_gen_ptr = NULL;
-    s->code_gen_prologue = buf0;
+
+#ifndef CONFIG_TCG_INTERPRETER
+    tcg_qemu_tb_exec = (tcg_prologue_fn *)buf0;
+#endif
 
     /* Compute a high-water mark, at which we voluntarily flush the buffer
        and start over.  The size here is arbitrary, significantly larger

tcg/tci.c

@@ -481,9 +481,9 @@ static bool tci_compare64(uint64_t u0, uint64_t u1, TCGCond condition)
  * One possible operation in the pseudo code is a call to binary code.
  * Therefore, disable CFI checks in the interpreter function
  */
-QEMU_DISABLE_CFI
-uintptr_t tcg_qemu_tb_exec(CPUArchState *env, uint8_t *tb_ptr)
+uintptr_t QEMU_DISABLE_CFI tcg_qemu_tb_exec(CPUArchState *env, void *v_tb_ptr)
 {
+    uint8_t *tb_ptr = v_tb_ptr;
     tcg_target_ulong regs[TCG_TARGET_NB_REGS];
     long tcg_temps[CPU_TEMP_BUF_NLONGS];
     uintptr_t sp_value = (uintptr_t)(tcg_temps + CPU_TEMP_BUF_NLONGS);