Implement args refinement

Fixes #771

Author: nunoplopes

ir/attrs.cpp

@@ -73,6 +73,27 @@ ostream& operator<<(ostream &os, const FnAttrs &attr) {
   return os;
 }
 
+bool ParamAttrs::refinedBy(const ParamAttrs &other) const {
+  // check attributes that are properties of the caller
+  unsigned attrs =
+    NonNull |
+    Dereferenceable |
+    NoUndef |
+    Align |
+    NoAlias |
+    DereferenceableOrNull
+  ;
+
+  auto other_params = (other.bits & attrs);
+  if ((bits & other_params) != other_params)
+    return false;
+
+  return derefBytes == other.derefBytes &&
+         derefOrNullBytes == other.derefOrNullBytes &&
+         blockSize == other.blockSize &&
+         align == other.align;
+}
+
 bool ParamAttrs::poisonImpliesUB() const {
   return has(Dereferenceable) || has(NoUndef) || has(ByVal) ||
          has(DereferenceableOrNull);

ir/attrs.h

@@ -30,6 +30,7 @@ class ParamAttrs final {
 
   bool has(Attribute a) const { return (bits & a) != 0; }
   void set(Attribute a) { bits |= (unsigned)a; }
+  bool refinedBy(const ParamAttrs &other) const;
 
   // Returns true if it's UB for the argument to be poison / have a poison elem.
   bool poisonImpliesUB() const;

ir/function.cpp

@@ -212,33 +212,6 @@ void Function::addInput(unique_ptr<Value> &&i) {
   inputs.emplace_back(move(i));
 }
 
-bool Function::hasSameInputs(const Function &rhs) const {
-  auto litr = inputs.begin(), lend = inputs.end();
-  auto ritr = rhs.inputs.begin(), rend = rhs.inputs.end();
-
-  auto skip_constinputs = [&]() {
-    while (litr != lend && dynamic_cast<ConstantInput *>((*litr).get()))
-      litr++;
-    while (ritr != rend && dynamic_cast<ConstantInput *>((*ritr).get()))
-      ritr++;
-  };
-
-  skip_constinputs();
-
-  while (litr != lend && ritr != rend) {
-    auto *lv = dynamic_cast<Input *>((*litr).get());
-    auto *rv = dynamic_cast<Input *>((*ritr).get());
-    if (lv->getType().toString() != rv->getType().toString())
-      return false;
-
-    ++litr;
-    ++ritr;
-    skip_constinputs();
-  }
-
-  return litr == lend && ritr == rend;
-}
-
 bool Function::hasReturn() const {
   for (auto &i : instrs()) {
     if (dynamic_cast<const Return *>(&i))

ir/function.h

@@ -133,7 +133,6 @@ class Function final {
   util::const_strip_unique_ptr<decltype(inputs)> getInputs() const {
     return inputs;
   }
-  bool hasSameInputs(const Function &rhs) const;
   Value *getReturnedInput() const { return returned_input; }
   void setReturnedInput(Value *v) { returned_input = v; }
 

tests/alive-tv/attrs/align-intro-withnoundef.srctgt.ll

@@ -1,5 +1,4 @@
-; Introduction of align AND noundef may introduce UB
-; ERROR: Source is more defined than target
+; ERROR: Parameter attributes not refined
 
 define i8* @src(i8* %p) {
   ret i8* %p

tests/alive-tv/attrs/align-intro.srctgt.ll

@@ -1,5 +1,4 @@
-; Introduction of align isn't immediate UB
-; ERROR: Target is more poisonous than source
+; ERROR: Parameter attributes not refined
 
 define i8* @src(i8* %p) {
   ret i8* %p

tests/alive-tv/attrs/dereferenceable_or_null.srctgt.ll

@@ -6,4 +6,4 @@ define i32* @tgt(i32* dereferenceable(4) %p) {
   ret i32* %p
 }
 
-; ERROR: Source is more defined than target
+; ERROR: Parameter attributes not refined

tests/alive-tv/attrs/dereferenceable_or_null2.srctgt.ll

@@ -5,3 +5,6 @@ define i32* @src(i32* dereferenceable(4) %p) {
 define i32* @tgt(i32* dereferenceable_or_null(4) %p) {
   ret i32* %p
 }
+
+; this one is technically ok, but it's not worth to support it
+; ERROR: Parameter attributes not refined

tests/alive-tv/attrs/nonnull-intro-withnoundef.srctgt.ll

@@ -1,5 +1,4 @@
-; Introduction of nonnull AND noundef may introduce UB
-; ERROR: Source is more defined than target
+; ERROR: Parameter attributes not refined
 
 define i8* @src(i8* %p) {
   ret i8* %p

tests/alive-tv/attrs/nonnull-intro.srctgt.ll

@@ -1,5 +1,4 @@
-; Introduction of nonnull isn't immediate UB
-; ERROR: Target is more poisonous than source
+; ERROR: Parameter attributes not refined
 
 define i8* @src(i8* %p) {
   ret i8* %p