Inline asm constraints: allow ICE-like pointers for the "n" constraint (PR40890)

Apparently GCC allows this, and there's code relying on it (see bug).

The idea is to allow expression that would have been allowed if they
were cast to int. So I based the code on how such a cast would be done
(the CK_PointerToIntegral case in IntExprEvaluator::VisitCastExpr()).

Differential Revision: https://reviews.llvm.org/D58821

llvm-svn: 355491

1 files changed, 20 insertions, 0 deletions

diff --git a/clang/lib/AST/APValue.cpp b/clang/lib/AST/APValue.cpp
index e1876a933dc..f9cbf331b28 100644
--- a/clang/lib/AST/APValue.cpp
+++ b/clang/lib/AST/APValue.cpp
@@ -614,6 +614,26 @@ std::string APValue::getAsString(ASTContext &Ctx, QualType Ty) const {
   return Result;
 }
 
+bool APValue::toIntegralConstant(APSInt &Result, QualType SrcTy,
+                                 const ASTContext &Ctx) const {
+  if (isInt()) {
+    Result = getInt();
+    return true;
+  }
+
+  if (isLValue() && isNullPointer()) {
+    Result = Ctx.MakeIntValue(Ctx.getTargetNullPointerValue(SrcTy), SrcTy);
+    return true;
+  }
+
+  if (isLValue() && !getLValueBase()) {
+    Result = Ctx.MakeIntValue(getLValueOffset().getQuantity(), SrcTy);
+    return true;
+  }
+
+  return false;
+}
+
 const APValue::LValueBase APValue::getLValueBase() const {
   assert(isLValue() && "Invalid accessor");
   return ((const LV*)(const void*)Data.buffer)->Base;