add _Alignof support

Author: WalterBright

README.md

@@ -6,7 +6,7 @@ http://www.digitalmars.com
 
 https://digitalmars.com/ctg/sc.html
 
-## Building the compiler:
+## Building the compiler (Win32 only):
 
 1. Download and install Digital Mars C++ compiler from https://www.digitalmars.com/download/freecompiler.html
 2. Download and install DMD 2.074.1 from http://downloads.dlang.org/releases/2017/
@@ -20,3 +20,5 @@ https://digitalmars.com/ctg/sc.html
    `make clean`
    `make scppn`
 You might need to edit the `makefile` to set the path to your DMD installation.
+
+Note that DMC targets Win32, and hasn't been ported to other platforms.

dm/src/dmc/cgelem.d

@@ -2140,6 +2140,8 @@ private elem * elcom(elem *e, goal_t goal)
 @trusted
 private elem * elcond(elem *e, goal_t goal)
 {
+    //printf("elcond() goal = %d\n", goal);
+    //elem_print(e);
     elem *e1 = e.EV.E1;
     switch (e1.Eoper)
     {
@@ -2388,12 +2390,60 @@ private elem * elcond(elem *e, goal_t goal)
                 e.EV.E1.EV.E1 = e1;
             }
 
+            /* Replace:
+             *   *p op e ? p : false
+             * with:
+             *   bool
+             */
+            else if (goal == GOALflags &&
+                ec2.Eoper == OPconst && !boolres(ec2) &&
+                typtr(ec1.Ety) &&
+                ec1.Eoper == OPvar &&
+                OTbinary(e1.Eoper) &&
+                !OTsideff(e1.Eoper) &&
+                e1.EV.E1.Eoper == OPind &&
+                el_match(findPointer(e1.EV.E1.EV.E1), ec1) &&
+                !el_sideeffect(e))
+            {
+                /* NOTE: should optimize other cases of this
+                 */
+                el_free(e.EV.E2);
+                e.EV.E2 = null;
+                e.Eoper = OPbool;
+                e.Ety = TYint;
+            }
             break;
         }
     }
     return e;
 }
 
+/******************************
+ * Given an elem that is the operand to OPind,
+ * find the expression representing the pointer.
+ * Params:
+ *      e = operand to OPind
+ * Returns:
+ *      expression that represents the pointer
+ */
+@trusted
+private elem* findPointer(elem* e)
+{
+    if (e.Eoper == OPvar)
+        return e;
+    if (OTleaf(e.Eoper) || !(e.Eoper == OPadd || e.Eoper == OPmin))
+        return null;
+
+    if (typtr(e.EV.E1.Ety))
+        return findPointer(e.EV.E1);
+    if (OTbinary(e.Eoper))
+    {
+        if (typtr(e.EV.E2.Ety))
+            return findPointer(e.EV.E2);
+    }
+    return null;
+}
+
 
 /****************************
  * Comma operator.

dm/src/dmc/dt.d

@@ -156,7 +156,7 @@ uint dt_size(const(dt_t)* dtstart)
 
 bool dtallzeros(const(dt_t)* dt)
 {
-    return dt.dt == DT_azeros && !dt.DTnext;
+    return dt && dt.dt == DT_azeros && !dt.DTnext;
 }
 
 /************************************

dm/src/dmc/gflow.d

@@ -334,6 +334,7 @@ private void initDNunambigVectors(DefNode[] defnod)
         if (vec_t v = defnod[i].DNunambig)
         {
             elem *e = defnod[i].DNelem;
+            vec_setbit(cast(uint) i, v);        // of course it modifies itself
             fillInDNunambig(v, e, i, defnod[]);
         }
     }
@@ -400,13 +401,16 @@ private void fillInDNunambig(vec_t v, elem *e, size_t start, DefNode[] defnod)
         if (d != tn1.EV.Vsym)
             continue;
 
-        // If t completely overlaps tn1
         tn1size = (tn.Eoper == OPstreq)
             ? type_size(tn.ET) : tysize(tn1.Ety);
-        if (toff <= tn1.EV.Voffset &&
-            tn1.EV.Voffset + tn1size <= ttop)
+        // If t completely overlaps tn1
+        if (toff <= tn1.EV.Voffset && tn1.EV.Voffset + tn1size <= ttop)
         {
             vec_setbit(cast(uint)i, v);
+        }
+        // if tn1 completely overlaps t
+        if (tn1.EV.Voffset <= toff && ttop <= tn1.EV.Voffset + tn1size)
+        {
             vec_setbit(cast(uint)start, v2);
         }
     }

dm/src/dmc/makefile

@@ -13,13 +13,6 @@
 
 DMCDIR=\dm
 
-#DMDDIR=e:\dmd2.074
-#DMDDIR79=e:\dmd2.079
-DMDDIR=e:\dmd2.079
-DMDDIR74=e:\dmd2.074
-DMDDIR79=e:\dmd2.079
-DMDDIR92=e:\dmd2.092
-
 CBX=.
 NTDLLSHELL=ntdllshell
 TK=tk
@@ -70,16 +63,7 @@ LFLAGS=/map/e/f/packcode/noe;
 ##### Tools
 
 # D compiler
-DMD=$(DMDDIR)\windows\bin\dmd
-DMD74=$(DMDDIR74)\windows\bin\dmd
-DMD79=$(DMDDIR79)\windows\bin\dmd
-DMDXX=$(DMDDIR74)\windows\bin\dmd
-
-DMD=$(DMDDIR92)\windows\bin\dmd
-DMD74=$(DMDDIR92)\windows\bin\dmd
-DMD79=$(DMDDIR92)\windows\bin\dmd
-DMDXX=$(DMDDIR92)\windows\bin\dmd
-
+DMD=dmd
 # C++ compiler
 CC=dmc
 # Make program
@@ -431,7 +415,7 @@ barray.obj : barray.d
         $(DMD) -c $(DFLAGS) barray.d
 
 bcomplex.obj : bcomplex.d
-        $(DMD79) -c $(DFLAGS) bcomplex.d
+        $(DMD) -c $(DFLAGS) bcomplex.d
 
 blockopt.obj : blockopt.d
         $(DMD) -c $(DFLAGS) blockopt.d
@@ -548,7 +532,7 @@ dnwc.obj : dnwc.d
         $(DMD) -c $(DFLAGS) dnwc.d
 
 dph.obj : dph.d page.di
-        $(DMD79) -c $(DFLAGS) dph.d
+        $(DMD) -c $(DFLAGS) dph.d
 
 dpragma.obj : dpragma.d
         $(DMD) -c $(DFLAGS) dpragma.d
@@ -560,10 +544,10 @@ dspeller.obj : dspeller.d
         $(DMD) -c $(DFLAGS) dspeller.d
 
 dtemplate.obj : dtemplate.d
-        $(DMD79) -c $(DFLAGS) dtemplate.d
+        $(DMD) -c $(DFLAGS) dtemplate.d
 
 dtype.obj : dtype.d
-        $(DMD79) -c $(DFLAGS) dtype.d
+        $(DMD) -c $(DFLAGS) dtype.d
 
 dwarfeh.obj : dwarfeh.d
         $(DMD) -c $(DFLAGS) dwarfeh.d