Fix Issue 14436 - Optimizer fails to remove comparison loop when comp…

…aring array against null
dlang · Apr 12, 2015 · 7660158 · 7660158
1 parent 7f8f27c
commit 7660158
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Showing 2 changed files with 17 additions and 2 deletions.
diff --git a/src/e2ir.c b/src/e2ir.c
@@ -2167,8 +2167,8 @@ elem *toElem(Expression *e, IRState *irs)
                     // Optimize comparisons of arrays of basic types
                     // For arrays of integers/characters, and void[],
                     // replace druntime call with:
-                    // For a==b: a.length==b.length && memcmp(a.ptr, b.ptr, size)==0
-                    // For a!=b: a.length!=b.length || memcmp(a.ptr, b.ptr, size)!=0
+                    // For a==b: a.length==b.length && (a.length == 0 || memcmp(a.ptr, b.ptr, size)==0)
+                    // For a!=b: a.length!=b.length || (a.length != 0 || memcmp(a.ptr, b.ptr, size)!=0)
                     // size is a.length*sizeof(a[0]) for dynamic arrays, or sizeof(a) for static arrays.
 
                     elem *earr1 = toElem(ee->e1, irs);
@@ -2212,6 +2212,10 @@ elem *toElem(Expression *e, IRState *irs)
                     e = el_bin(OPmemcmp, TYint, e, esize);
                     e = el_bin(eop, TYint, e, el_long(TYint, 0));
 
+                    elem *elen = t2->ty == Tsarray ? elen2 : elen1;
+                    elem *esizecheck = el_bin(eop, TYint, el_same(&elen), el_long(TYsize_t, 0));
+                    e = el_bin(ee->op == TOKequal ? OPoror : OPandand, TYint, esizecheck, e);
+
                     if (t1->ty == Tsarray && t2->ty == Tsarray)
                         assert(t1->size() == t2->size());
                     else

diff --git a/test/runnable/mars1.d b/test/runnable/mars1.d
@@ -1280,6 +1280,16 @@ int test13969(const S13969* f) {
 
 ////////////////////////////////////////////////////////////////////////
 
+int[] arr14436;
+void test14436()
+{
+    assert(arr14436 == null);
+    arr14436 = [1, 2, 3];
+    assert(arr14436 != null);
+}
+
+////////////////////////////////////////////////////////////////////////
+
 void test14220()
 {
     auto a = toString(14);
@@ -1347,6 +1357,7 @@ int main()
     test13383();
     test13190();
     test13485();
+    test14436();
     test10639();
     test10715();
     test10678();