fix #951: false-positive condition for loop sinks doesn't take nonret…

…urn functions into account

ir/state.cpp

@@ -1238,7 +1238,7 @@ expr State::sinkDomain() const {
 
   OrExpr ret;
   for (auto &[src, data] : I->second) {
-    ret.add(data.path());
+    ret.add(data.path() && *data.UB());
   }
   return ret();
 }

tests/alive-tv/loops/issue951.srctgt.ll

@@ -0,0 +1,38 @@
+; ERROR: Source is more defined than target
+; TEST-ARGS: -src-unroll=3 -tgt-unroll=3
+
+define i8 @src(i8 %v) {
+entry:
+  %v.nonneg = icmp sgt i8 %v, -1
+  br label %for.body
+
+for.body:
+  %sum = phi i8 [ 0, %entry ], [ %sum.next, %for.body ]
+  %sum.next = add i8 %sum, %v
+  %overflow = icmp ult i8 %sum.next, %sum
+  %cmp.i5.i = xor i1 %v.nonneg, %overflow
+  call void @use(i1 %cmp.i5.i)
+  br i1 %cmp.i5.i, label %for.body, label %cleanup1.loopexit
+
+cleanup1.loopexit:
+  %cmp.not.lcssa.ph = phi i8 [ %sum, %for.body ]
+  ret i8 %cmp.not.lcssa.ph
+}
+
+define i8 @tgt(i8 %v) {
+entry:
+  %v.nonneg = icmp sgt i8 %v, -1
+  br label %for.body
+
+for.body:
+  %sum = phi i8 [ 0, %entry ], [ %sum.next, %for.body ]
+  %sum.next = add i8 %sum, %v
+  call void @use(i1 %v.nonneg)
+  br i1 %v.nonneg, label %for.body, label %cleanup1.loopexit
+
+cleanup1.loopexit:
+  %cmp.not.lcssa.ph = phi i8 [ %sum, %for.body ]
+  ret i8 %cmp.not.lcssa.ph
+}
+
+declare void @use(i1)