Revert part of r206963

Specifically the part where we removed a warning to be compatible with GCC, which has been widely regarded as a bad idea.

I'm not quite happy with how obtuse this warning is, especially in the fairly common case of a 32-bit integer literal, so I've got another patch awaiting review that adds a fixit to reduce confusion.

llvm-svn: 213935

1 files changed, 27 insertions, 0 deletions

diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
index b0ca5a547c5..e78244d95c6 100644
--- a/clang/lib/Basic/Targets.cpp
+++ b/clang/lib/Basic/Targets.cpp
@@ -4503,6 +4503,33 @@ public:
     return false;
   }
 
+  virtual bool validateConstraintModifier(StringRef Constraint,
+                                          const char Modifier,
+                                          unsigned Size) const {
+    // Strip off constraint modifiers.
+    while (Constraint[0] == '=' || Constraint[0] == '+' || Constraint[0] == '&')
+      Constraint = Constraint.substr(1);
+
+    switch (Constraint[0]) {
+    default:
+      return true;
+    case 'z':
+    case 'r': {
+      switch (Modifier) {
+      case 'x':
+      case 'w':
+        // For now assume that the person knows what they're
+        // doing with the modifier.
+        return true;
+      default:
+        // By default an 'r' constraint will be in the 'x'
+        // registers.
+        return Size == 64;
+      }
+    }
+    }
+  }
+
   virtual const char *getClobbers() const { return ""; }
 
   int getEHDataRegisterNumber(unsigned RegNo) const {