optimize unsigned / to >=

dlang · Sep 9, 2017 · ebba9c6 · ebba9c6
1 parent b6b8dbf
commit ebba9c6
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Showing 2 changed files with 33 additions and 1 deletion.
diff --git a/src/ddmd/backend/cgelem.c b/src/ddmd/backend/cgelem.c
@@ -1434,13 +1434,20 @@ STATIC elem * elbitwise(elem *e, goal_t goal)
             ELCONST(e1->E1,1) &&
             tysize(e->E1->Ety) <= REGSIZE)
         {
+            int sz = tysize(e->E1->Ety);
             e->Eoper = OPbtst;
             e->Ety = TYbool;
             e->E1 = e2;
             e->E2 = e1->E2;
             e->E2->Ety = e->E1->Ety;
             e1->E2 = NULL;
             el_free(e1);
+            if (sz >= 2)
+                e = el_una(OPu8_16, TYushort, e);
+            if (sz >= 4)
+                e = el_una(OPu16_32, TYulong, e);
+            if (sz >= 8)
+                e = el_una(OPu32_64, TYullong, e);
             return optelem(e, goal);
         }
     }
@@ -2398,6 +2405,15 @@ STATIC elem * eldiv(elem *e, goal_t goal)
             }
         }
 
+        /* Convert if(e1/e2) to if(e1>=e2) iff unsigned division.
+         */
+        if (goal == GOALflags && uns && e->Eoper == OPdiv)
+        {
+            e->Eoper = OPge;
+            e->Ety = TYbool;
+            return e;
+        }
+
         /* TODO: (i*c1)/c2 => i*(c1/c2) if (c1%c2)==0
          * TODO: i/(x?c1:c2) => i>>(x?log2(c1):log2(c2)) if c1 and c2 are powers of 2
          */
@@ -2431,6 +2447,7 @@ STATIC elem * eldiv(elem *e, goal_t goal)
                     e->Eoper = OPremquo;
                     e = el_una(op, tym, e);
                     e->E1->Ety = (sz == 2) ? TYlong : (sz == 4) ? TYllong : TYcent;
+                    return e;
                 }
             }
         }
@@ -5516,7 +5533,6 @@ STATIC elem * optelem(elem *e, goal_t goal)
 elem *doptelem(elem *e, goal_t goal)
 {
     //printf("doptelem(e = %p, goal = x%x)\n", e, goal);
-
     assert(!PARSER);
     do
     {   again = false;

diff --git a/test/runnable/mars1.d b/test/runnable/mars1.d
@@ -1662,6 +1662,21 @@ void testeqeqranges()
 
 ////////////////////////////////////////////////////////////////////////
 
+void testdivcmp()
+{
+    // https://github.com/dlang/dmd/pull/7128
+    static bool foo(uint a, uint b)
+    {
+        return cast(bool)(a / b); // convert / to >=
+    }
+
+    assert(!foo(3, 4));
+    assert(foo(4, 4));
+    assert(foo(5, 4));
+}
+
+////////////////////////////////////////////////////////////////////////
+
 int main()
 {
     testgoto();
@@ -1720,6 +1735,7 @@ int main()
     test5();
     test6();
     testeqeqranges();
+    testdivcmp();
     printf("Success\n");
     return 0;
 }