tcg: Document tb_lookup() and tcg_tb_lookup()

These similarly named functions serve different purposes; add
docstrings to highlight them.

Suggested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20250116213214.5695-1-iii@linux.ibm.com>

accel/tcg/cpu-exec.c

@@ -249,7 +249,20 @@ static TranslationBlock *tb_htable_lookup(CPUState *cpu, vaddr pc,
     return qht_lookup_custom(&tb_ctx.htable, &desc, h, tb_lookup_cmp);
 }
 
-/* Might cause an exception, so have a longjmp destination ready */
+/**
+ * tb_lookup:
+ * @cpu: CPU that will execute the returned translation block
+ * @pc: guest PC
+ * @cs_base: arch-specific value associated with translation block
+ * @flags: arch-specific translation block flags
+ * @cflags: CF_* flags
+ *
+ * Look up a translation block inside the QHT using @pc, @cs_base, @flags and
+ * @cflags. Uses @cpu's tb_jmp_cache. Might cause an exception, so have a
+ * longjmp destination ready.
+ *
+ * Returns: an existing translation block or NULL.
+ */
 static inline TranslationBlock *tb_lookup(CPUState *cpu, vaddr pc,
                                           uint64_t cs_base, uint32_t flags,
                                           uint32_t cflags)

include/tcg/tcg.h

@@ -638,10 +638,51 @@ void tcg_region_reset_all(void);
 size_t tcg_code_size(void);
 size_t tcg_code_capacity(void);
 
+/**
+ * tcg_tb_insert:
+ * @tb: translation block to insert
+ *
+ * Insert @tb into the region trees.
+ */
 void tcg_tb_insert(TranslationBlock *tb);
+
+/**
+ * tcg_tb_remove:
+ * @tb: translation block to remove
+ *
+ * Remove @tb from the region trees.
+ */
 void tcg_tb_remove(TranslationBlock *tb);
+
+/**
+ * tcg_tb_lookup:
+ * @tc_ptr: host PC to look up
+ *
+ * Look up a translation block inside the region trees by @tc_ptr. This is
+ * useful for exception handling, but must not be used for the purposes of
+ * executing the returned translation block. See struct tb_tc for more
+ * information.
+ *
+ * Returns: a translation block previously inserted into the region trees,
+ * such that @tc_ptr points anywhere inside the code generated for it, or
+ * NULL.
+ */
 TranslationBlock *tcg_tb_lookup(uintptr_t tc_ptr);
+
+/**
+ * tcg_tb_foreach:
+ * @func: callback
+ * @user_data: opaque value to pass to @callback
+ *
+ * Call @func for each translation block inserted into the region trees.
+ */
 void tcg_tb_foreach(GTraverseFunc func, gpointer user_data);
+
+/**
+ * tcg_nb_tbs:
+ *
+ * Returns: the number of translation blocks inserted into the region trees.
+ */
 size_t tcg_nb_tbs(void);
 
 /* user-mode: Called with mmap_lock held.  */