[clang][Interp] Optionally cast comparison result to non-bool

Our comparison opcodes always produce a Boolean value and push it on the
stack. However, the result of such a comparison in C is int, so the
later code expects an integer value on the stack.

Work around this problem by casting the boolean value to int in those
cases. This is not ideal for C however. The comparison is usually
wrapped in a IntegerToBool cast anyway.

Differential Revision: https://reviews.llvm.org/D149645

diff --git a/clang/lib/AST/Interp/ByteCodeExprGen.cpp b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
index df7c4a7..24663a1 100644 (file)
--- a/clang/lib/AST/Interp/ByteCodeExprGen.cpp
+++ b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -237,19 +237,31 @@ bool ByteCodeExprGen<Emitter>::VisitBinaryOperator(const BinaryOperator *BO) {
   if (!visit(LHS) || !visit(RHS))
     return false;
 
+  // For languages such as C, cast the result of one
+  // of our comparision opcodes to T (which is usually int).
+  auto MaybeCastToBool = [this, T, BO](bool Result) {
+    if (!Result)
+      return false;
+    if (DiscardResult)
+      return this->emitPop(*T, BO);
+    if (T != PT_Bool)
+      return this->emitCast(PT_Bool, *T, BO);
+    return true;
+  };
+
   switch (BO->getOpcode()) {
   case BO_EQ:
-    return Discard(this->emitEQ(*LT, BO));
+    return MaybeCastToBool(this->emitEQ(*LT, BO));
   case BO_NE:
-    return Discard(this->emitNE(*LT, BO));
+    return MaybeCastToBool(this->emitNE(*LT, BO));
   case BO_LT:
-    return Discard(this->emitLT(*LT, BO));
+    return MaybeCastToBool(this->emitLT(*LT, BO));
   case BO_LE:
-    return Discard(this->emitLE(*LT, BO));
+    return MaybeCastToBool(this->emitLE(*LT, BO));
   case BO_GT:
-    return Discard(this->emitGT(*LT, BO));
+    return MaybeCastToBool(this->emitGT(*LT, BO));
   case BO_GE:
-    return Discard(this->emitGE(*LT, BO));
+    return MaybeCastToBool(this->emitGE(*LT, BO));
   case BO_Sub:
     if (BO->getType()->isFloatingType())
       return Discard(this->emitSubf(getRoundingMode(BO), BO));

diff --git a/clang/test/AST/Interp/c.c b/clang/test/AST/Interp/c.c
new file mode 100644 (file)
index 0000000..248494c
--- /dev/null
+++ b/clang/test/AST/Interp/c.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -verify %s
+// RUN: %clang_cc1 -verify=ref %s
+
+/// expected-no-diagnostics
+/// ref-no-diagnostics
+
+_Static_assert(1, "");
+_Static_assert(0 != 1, "");
+_Static_assert(1.0 == 1.0, "");
+_Static_assert( (5 > 4) + (3 > 2) == 2, "");