[X86 inline-asm] Error out on inline-asm constraint "=f".

<rdar://problem/17476689>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@213428 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Basic/Targets.cpp b/lib/Basic/Targets.cpp
index 49e94442abd16aece6ebb3b824c07f87291fb875..fe72fe1e19abd930a39ccc6900ae1b6c3d5d3563 100644 (file)
--- a/lib/Basic/Targets.cpp
+++ b/lib/Basic/Targets.cpp
@@ -2927,6 +2927,13 @@ X86TargetInfo::validateAsmConstraint(const char *&Name,
     case 'm':  // any MMX register, when inter-unit moves enabled.
       break;   // falls through to setAllowsRegister.
   }
+  case 'f': // any x87 floating point stack register.
+    // Constraint 'f' cannot be used for output operands.
+    if (Info.ConstraintStr[0] == '=')
+      return false;
+
+    Info.setAllowsRegister();
+    return true;
   case 'a': // eax.
   case 'b': // ebx.
   case 'c': // ecx.
@@ -2934,7 +2941,6 @@ X86TargetInfo::validateAsmConstraint(const char *&Name,
   case 'S': // esi.
   case 'D': // edi.
   case 'A': // edx:eax.
-  case 'f': // any x87 floating point stack register.
   case 't': // top of floating point stack.
   case 'u': // second from top of floating point stack.
   case 'q': // Any register accessible as [r]l: a, b, c, and d.

diff --git a/test/Sema/asm.c b/test/Sema/asm.c
index 22b74974ce262d62430782a4707f6bff06446bd1..89c8c574eb5a334cb671be1b5330c5487745996d 100644 (file)
--- a/test/Sema/asm.c
+++ b/test/Sema/asm.c
@@ -157,3 +157,9 @@ struct foo {
 };
 register struct foo bar asm("sp"); // expected-error {{bad type for named register variable}}
 register float baz asm("sp"); // expected-error {{bad type for named register variable}}
+
+double f_output_constraint(void) {
+  double result;
+  __asm("foo1": "=f" (result)); // expected-error {{invalid output constraint '=f' in asm}}
+  return result;
+}