Re: [Qemu-devel] Proposal for host-utils

["J. Mayer" <l_indien@magic.fr>]

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On Sun, 2007-10-28 at 00:53 +0200, J. Mayer wrote:
> Following the previous discussions about host-utils implementations,
> here's a patch with the following changes:
> - move mulu64 and muls64 definitions from exec.h to host-utils.h, for
> consistency
> - include host-utils.h in more files to reflect this change
> - make the optimized version of mulu64 / muls64 for amd64 hosts static
> inline
> - change clz64 to avoid 64 bits logical operations to optimize the 32
> bits host case
> - add ctz32, ctz64, cto32 and cto64, using the same method than ctlzxx /
> cloxx implementations
> - add ctpop8, ctpop16, ctpop32 and ctpop64, using the Sparc target
> implementation method
>   ctpop8 is used by the PowerPC target, I added ctpop16 for consistency
> - change the Alpha and the PowerPC targets to use those helpers

I did commit the ctz, cto and ctpop helpers. I have a remaining patch
that contains the changes for mulu64 / muls64 and optimize clz64 and
clo64, avoiding 64 bits values manipulation, which may help when running
on a 32 bits host.

Please comment.

-- 
J. Mayer <l_indien@magic.fr>
Never organized

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Index: exec-all.h
===================================================================
RCS file: /sources/qemu/qemu/exec-all.h,v
retrieving revision 1.69
diff -u -d -d -p -r1.69 exec-all.h
--- exec-all.h	20 Oct 2007 19:45:43 -0000	1.69
+++ exec-all.h	28 Oct 2007 12:59:46 -0000
@@ -91,9 +91,6 @@ void optimize_flags_init(void);
 extern FILE *logfile;
 extern int loglevel;
 
-void muls64(int64_t *phigh, int64_t *plow, int64_t a, int64_t b);
-void mulu64(uint64_t *phigh, uint64_t *plow, uint64_t a, uint64_t b);
-
 int gen_intermediate_code(CPUState *env, struct TranslationBlock *tb);
 int gen_intermediate_code_pc(CPUState *env, struct TranslationBlock *tb);
 void dump_ops(const uint16_t *opc_buf, const uint32_t *opparam_buf);
Index: host-utils.c
===================================================================
RCS file: /sources/qemu/qemu/host-utils.c,v
retrieving revision 1.4
diff -u -d -d -p -r1.4 host-utils.c
--- host-utils.c	26 Oct 2007 22:35:01 -0000	1.4
+++ host-utils.c	28 Oct 2007 12:59:46 -0000
@@ -28,6 +28,7 @@
 //#define DEBUG_MULDIV
 
 /* Long integer helpers */
+#if !defined(__x86_64__)
 static void add128 (uint64_t *plow, uint64_t *phigh, uint64_t a, uint64_t b)
 {
     *plow += a;
@@ -69,17 +70,10 @@ static void mul64 (uint64_t *plow, uint6
     *phigh += v;
 }
 
-
 /* Unsigned 64x64 -> 128 multiplication */
 void mulu64 (uint64_t *plow, uint64_t *phigh, uint64_t a, uint64_t b)
 {
-#if defined(__x86_64__)
-    __asm__ ("mul %0\n\t"
-             : "=d" (*phigh), "=a" (*plow)
-             : "a" (a), "0" (b));
-#else
     mul64(plow, phigh, a, b);
-#endif
 #if defined(DEBUG_MULDIV)
     printf("mulu64: 0x%016llx * 0x%016llx = 0x%016llx%016llx\n",
            a, b, *phigh, *plow);
@@ -89,11 +83,6 @@ void mulu64 (uint64_t *plow, uint64_t *p
 /* Signed 64x64 -> 128 multiplication */
 void muls64 (uint64_t *plow, uint64_t *phigh, int64_t a, int64_t b)
 {
-#if defined(__x86_64__)
-    __asm__ ("imul %0\n\t"
-             : "=d" (*phigh), "=a" (*plow)
-             : "a" (a), "0" (b));
-#else
     int sa, sb;
 
     sa = (a < 0);
@@ -106,9 +95,9 @@ void muls64 (uint64_t *plow, uint64_t *p
     if (sa ^ sb) {
         neg128(plow, phigh);
     }
-#endif
 #if defined(DEBUG_MULDIV)
     printf("muls64: 0x%016llx * 0x%016llx = 0x%016llx%016llx\n",
            a, b, *phigh, *plow);
 #endif
 }
+#endif /* !defined(__x86_64__) */
Index: host-utils.h
===================================================================
RCS file: /sources/qemu/qemu/host-utils.h,v
retrieving revision 1.2
diff -u -d -d -p -r1.2 host-utils.h
--- host-utils.h	28 Oct 2007 12:52:38 -0000	1.2
+++ host-utils.h	28 Oct 2007 12:59:46 -0000
@@ -23,6 +23,26 @@
  * THE SOFTWARE.
  */
 
+#if defined(__x86_64__)
+static always_inline void mulu64 (uint64_t *plow, uint64_t *phigh,
+                                  uint64_t a, uint64_t b)
+{
+    __asm__ ("mul %0\n\t"
+             : "=d" (*phigh), "=a" (*plow)
+             : "a" (a), "0" (b));
+}
+static always_inline void muls64 (uint64_t *plow, uint64_t *phigh,
+                                  int64_t a, int64_t b)
+{
+    __asm__ ("imul %0\n\t"
+             : "=d" (*phigh), "=a" (*plow)
+             : "a" (a), "0" (b));
+}
+#else
+void muls64(int64_t *phigh, int64_t *plow, int64_t a, int64_t b);
+void mulu64(uint64_t *phigh, uint64_t *plow, uint64_t a, uint64_t b);
+#endif
+
 /* Note that some of those functions may end up calling libgcc functions,
    depending on the host machine. It is up to the target emulation to
    cope with that. */
@@ -68,34 +88,13 @@ static always_inline int clz64(uint64_t 
 {
     int cnt = 0;
 
-    if (!(val & 0xFFFFFFFF00000000ULL)) {
+    if (!(val >> 32)) {
         cnt += 32;
-        val <<= 32;
-    }
-    if (!(val & 0xFFFF000000000000ULL)) {
-        cnt += 16;
-        val <<= 16;
-    }
-    if (!(val & 0xFF00000000000000ULL)) {
-        cnt += 8;
-        val <<= 8;
-    }
-    if (!(val & 0xF000000000000000ULL)) {
-        cnt += 4;
-        val <<= 4;
-    }
-    if (!(val & 0xC000000000000000ULL)) {
-        cnt += 2;
-        val <<= 2;
-    }
-    if (!(val & 0x8000000000000000ULL)) {
-        cnt++;
-        val <<= 1;
-    }
-    if (!(val & 0x8000000000000000ULL)) {
-        cnt++;
+    } else {
+        val >>= 32;
     }
-    return cnt;
+
+    return cnt + clz32(val);
 }
 
 static always_inline int clo64(uint64_t val)
Index: target-alpha/op.c
===================================================================
RCS file: /sources/qemu/qemu/target-alpha/op.c,v
retrieving revision 1.4
diff -u -d -d -p -r1.4 op.c
--- target-alpha/op.c	25 Oct 2007 23:34:44 -0000	1.4
+++ target-alpha/op.c	28 Oct 2007 12:59:46 -0000
@@ -22,6 +22,7 @@
 
 #include "config.h"
 #include "exec.h"
+#include "host-utils.h"
 
 #include "op_helper.h"
 
Index: target-i386/helper.c
===================================================================
RCS file: /sources/qemu/qemu/target-i386/helper.c,v
retrieving revision 1.91
diff -u -d -d -p -r1.91 helper.c
--- target-i386/helper.c	26 Oct 2007 22:35:02 -0000	1.91
+++ target-i386/helper.c	28 Oct 2007 12:59:47 -0000
@@ -18,6 +18,7 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 #include "exec.h"
+#include "host-utils.h"
 
 //#define DEBUG_PCALL