tcg: use tcg_debug_assert instead of assert (fix performance regression)

The TCG code is quite performance sensitive, but at the same time can
also be quite tricky. That is why asserts that can be enabled with the
--enable-debug-tcg configure option.

This used to work the following way:

| #include "config.h"
|
| ...
|
| #if !defined(CONFIG_DEBUG_TCG) && !defined(NDEBUG)
| /* define it to suppress various consistency checks (faster) */
| #define NDEBUG
| #endif
|
| ...
|
| #include <assert.h>

Since commit 757e725b (tcg: Clean up includes) "config.h" as been
replaced by "qemu/osdep.h" which itself includes <assert.h>. As a
consequence the assertions are always enabled, even when using
--disable-debug-tcg, causing a performance regression, especially on
targets with many registers. For instance on qemu-system-ppc the
speed difference is about 15%.

tcg_debug_assert is controlled directly by CONFIG_DEBUG_TCG and already
uses in some places. This patch replaces all the calls to assert into
calss to tcg_debug_assert.

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Message-id: 1461228530-14852-1-git-send-email-aurelien@aurel32.net
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/tcg/i386/tcg-target.inc.c b/tcg/i386/tcg-target.inc.c
index 9187d34caf..65f0d4c449 100644
--- a/tcg/i386/tcg-target.inc.c
+++ b/tcg/i386/tcg-target.inc.c
@@ -425,7 +425,7 @@ static void tcg_out_opc(TCGContext *s, int opc, int r, int rm, int x)
     }
     if (opc & P_DATA16) {
         /* We should never be asking for both 16 and 64-bit operation.  */
-        assert((opc & P_REXW) == 0);
+        tcg_debug_assert((opc & P_REXW) == 0);
         tcg_out8(s, 0x66);
     }
     if (opc & P_ADDR32) {
@@ -599,7 +599,7 @@ static void tcg_out_modrm_sib_offset(TCGContext *s, int opc, int r, int rm,
         if (index < 0) {
             index = 4;
         } else {
-            assert(index != TCG_REG_ESP);
+            tcg_debug_assert(index != TCG_REG_ESP);
         }
 
         tcg_out_opc(s, opc, r, rm, index);
@@ -745,14 +745,14 @@ static inline void tcg_out_rolw_8(TCGContext *s, int reg)
 static inline void tcg_out_ext8u(TCGContext *s, int dest, int src)
 {
     /* movzbl */
-    assert(src < 4 || TCG_TARGET_REG_BITS == 64);
+    tcg_debug_assert(src < 4 || TCG_TARGET_REG_BITS == 64);
     tcg_out_modrm(s, OPC_MOVZBL + P_REXB_RM, dest, src);
 }
 
 static void tcg_out_ext8s(TCGContext *s, int dest, int src, int rexw)
 {
     /* movsbl */
-    assert(src < 4 || TCG_TARGET_REG_BITS == 64);
+    tcg_debug_assert(src < 4 || TCG_TARGET_REG_BITS == 64);
     tcg_out_modrm(s, OPC_MOVSBL + P_REXB_RM + rexw, dest, src);
 }