tcg: Respect highwater in tcg_out_tb_finalize

Undo the workaround at b17a6d3390f87620735f7efb03bb1c96682ff449.

If there are lots of memory operations in a TB, the slow path code
can exceed the highwater reservation.  Add a check within the loop.

Tested-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>

1 files changed, 10 insertions, 1 deletions

diff --git a/tcg/tcg-be-ldst.h b/tcg/tcg-be-ldst.h
index 40a2369b7c..17777aec5a 100644
--- a/tcg/tcg-be-ldst.h
+++ b/tcg/tcg-be-ldst.h
@@ -56,7 +56,7 @@ static inline void tcg_out_tb_init(TCGContext *s)
 static void tcg_out_qemu_ld_slow_path(TCGContext *s, TCGLabelQemuLdst *l);
 static void tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *l);
 
-static void tcg_out_tb_finalize(TCGContext *s)
+static bool tcg_out_tb_finalize(TCGContext *s)
 {
     TCGLabelQemuLdst *lb;
 
@@ -67,7 +67,16 @@ static void tcg_out_tb_finalize(TCGContext *s)
         } else {
             tcg_out_qemu_st_slow_path(s, lb);
         }
+
+        /* Test for (pending) buffer overflow.  The assumption is that any
+           one operation beginning below the high water mark cannot overrun
+           the buffer completely.  Thus we can test for overflow after
+           generating code without having to check during generation.  */
+        if (unlikely((void *)s->code_ptr > s->code_gen_highwater)) {
+            return false;
+        }
     }
+    return true;
 }
 
 /*