Don't give warnings about constant folding late in the compilation

p4lang · Nov 18, 2016 · 9458e69 · 9458e69
1 parent 5f69305
commit 9458e69
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Showing 3 changed files with 10 additions and 8 deletions.
diff --git a/backends/bmv2/midend.cpp b/backends/bmv2/midend.cpp
@@ -148,7 +148,7 @@ MidEnd::MidEnd(CompilerOptions& options) {
         new P4::RemoveLeftSlices(&refMap, &typeMap),
         new P4::TypeChecking(&refMap, &typeMap),
         new LowerExpressions(&typeMap),
-        new P4::ConstantFolding(&refMap, &typeMap),
+        new P4::ConstantFolding(&refMap, &typeMap, false),
         evaluator,
         new VisitFunctor([this, evaluator]() { toplevel = evaluator->getToplevelBlock(); })
     });

diff --git a/frontends/common/constantFolding.cpp b/frontends/common/constantFolding.cpp
@@ -567,7 +567,7 @@ const IR::Node* DoConstantFolding::shift(const IR::Operation_Binary* e) {
 
     auto tb = left->type->to<IR::Type_Bits>();
     if (tb != nullptr) {
-        if ((unsigned)tb->size < shift)
+        if (((unsigned)tb->size < shift) && warnings)
             ::warning("%1%: Shifting %2%-bit value with %3%", e, tb->size, shift);
     }
 
@@ -710,7 +710,8 @@ const IR::Node* DoConstantFolding::postorder(IR::SelectExpression* expression) {
      * Should really implement this in SelectCase pre/postorder and this postorder goes away */
     for (auto c : expression->selectCases) {
         if (finished) {
-            ::warning("%1%: unreachable case", c);
+            if (warnings)
+                ::warning("%1%: unreachable case", c);
             continue;
         }
         auto inside = setContains(c->keyset, sel);
@@ -735,7 +736,7 @@ const IR::Node* DoConstantFolding::postorder(IR::SelectExpression* expression) {
     }
 
     if (changes) {
-        if (cases.size() == 0 && result == expression)
+        if (cases.size() == 0 && result == expression && warnings)
             // TODO: this is the same as verify(false, error.NoMatch),
             // but we cannot replace the selectExpression with a method call.
             ::warning("%1%: no case matches", expression);

diff --git a/frontends/common/constantFolding.h b/frontends/common/constantFolding.h
@@ -30,6 +30,7 @@ class DoConstantFolding : public Transform {
     const ReferenceMap* refMap;  // if null no 'const' values can be resolved
     TypeMap* typeMap;  // if null we have no types; updated for new constants
     bool typesKnown;
+    bool warnings;  // if true emit warnings
     // maps expressions and declarations to their constant values
     std::map<const IR::Node*, const IR::Expression*> constants;
 
@@ -55,8 +56,8 @@ class DoConstantFolding : public Transform {
     Result setContains(const IR::Expression* keySet, const IR::Expression* constant) const;
 
  public:
-    DoConstantFolding(const ReferenceMap* refMap, TypeMap* typeMap) :
-            refMap(refMap), typeMap(typeMap), typesKnown(typeMap != nullptr) {
+    DoConstantFolding(const ReferenceMap* refMap, TypeMap* typeMap, bool warnings = true) :
+            refMap(refMap), typeMap(typeMap), typesKnown(typeMap != nullptr), warnings(warnings) {
         visitDagOnce = true; setName("DoConstantFolding");
     }
 
@@ -92,10 +93,10 @@ class DoConstantFolding : public Transform {
 
 class ConstantFolding : public PassManager {
  public:
-    ConstantFolding(ReferenceMap* refMap, TypeMap* typeMap) {
+    ConstantFolding(ReferenceMap* refMap, TypeMap* typeMap, bool warnings = true) {
         if (typeMap != nullptr)
             passes.push_back(new TypeChecking(refMap, typeMap));
-        passes.push_back(new DoConstantFolding(refMap, typeMap));
+        passes.push_back(new DoConstantFolding(refMap, typeMap, warnings));
         setName("ConstantFolding");
     }
 };