optimization pattern

dlang · Aug 6, 2011 · ffcae90 · ffcae90
1 parent c75ccdd
commit ffcae90
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Showing 2 changed files with 34 additions and 4 deletions.
diff --git a/src/backend/cgelem.c b/src/backend/cgelem.c
@@ -1398,6 +1398,36 @@ STATIC elem *elor(elem *e)
     return elbitwise(e);
 }
 
+/*************************************
+ */
+
+STATIC elem *elxor(elem *e)
+{
+    if (OPTIMIZER)
+    {
+        elem *e1 = e->E1;
+        elem *e2 = e->E2;
+
+        /* Recognize:
+         *    (a & c) ^ (b & c)  =>  (a ^ b) & c
+         */
+        if (e1->Eoper == OPand && e2->Eoper == OPand &&
+            el_match5(e1->E2, e2->E2) &&
+            (e2->E2->Eoper == OPconst || (!el_sideeffect(e2->E1) && !el_sideeffect(e2->E2))))
+        {
+            el_free(e1->E2);
+            e1->E2 = e2->E1;
+            e1->Eoper = OPxor;
+            e->Eoper = OPand;
+            e->E2 = e2->E2;
+            e2->E1 = NULL;
+            e2->E2 = NULL;
+            el_free(e2);
+            return optelem(e, TRUE);
+        }
+    }
+    return elbitwise(e);
+}
 
 /**************************
  * Optimize nots.

diff --git a/src/backend/optabgen.c b/src/backend/optabgen.c
@@ -1,5 +1,5 @@
 // Copyright (C) 1985-1998 by Symantec
-// Copyright (C) 2000-2009 by Digital Mars
+// Copyright (C) 2000-2011 by Digital Mars
 // All Rights Reserved
 // http://www.digitalmars.com
 // Written by Walter Bright
@@ -428,7 +428,7 @@ void dotab()
         case OPremquo:  X("/%",         elremquo, cdmul);
         case OPdiv:     X("/",          eldiv,  cdmul);
         case OPmod:     X("%",          elmod,  cdmul);
-        case OPxor:     X("^",          elbitwise,cdorth);
+        case OPxor:     X("^",          elxor,  cdorth);
         case OPvptrfptr: X("vptrfptr",  elvptrfptr,cdcnvt);
         case OPcvptrfptr: X("cvptrfptr", elvptrfptr,cdcnvt);
         case OPstring:  X("string",     elstring,cderr);
@@ -805,7 +805,7 @@ void dotytab()
 "wchar_t",      TYwchar_t,      TYwchar_t, TYint,       SHORTSIZE, 0x85,0x71,
 "unsigned short",TYushort,      TYushort,  TYint,       SHORTSIZE, 0x85,0x21,
 
-// These values are adjusted for 32 bit ints in cv_init() and util_set386()
+// These values are adjusted for 32 bit ints in cv_init() and util_set32()
 "enum",         TYenum,         TYuint,    TYint,       -1,        0x81,0x72,
 "int",          TYint,          TYuint,    TYint,       2,         0x81,0x72,
 "unsigned",     TYuint,         TYuint,    TYint,       2,         0x85,0x73,
@@ -1014,7 +1014,7 @@ void dotytab()
         _tyequiv[i] = i;
     _tyequiv[TYchar] = TYschar;         /* chars are signed by default  */
 
-    // These values are adjusted in util_set386() for 32 bit ints
+    // These values are adjusted in util_set32() for 32 bit ints
     _tyequiv[TYint] = TYshort;
     _tyequiv[TYuint] = TYushort;