[inline-asm]No error for conflict between inputs\outputs and clobber list

According to extended asm syntax, a case where the clobber list includes a variable from the inputs or outputs should be an error - conflict.
for example:

const long double a = 0.0;
int main()
{

char b;
double t1 = a;
__asm__ ("fucompp": "=a" (b) : "u" (t1), "t" (t1) : "cc", "st", "st(1)");

return 0;
}

This should conflict with the output - t1 which is st, and st which is st aswell.
The patch fixes it.

Commit on behald of Ziv Izhar.

Differential Revision: https://reviews.llvm.org/D15075

llvm-svn: 290539

1 files changed, 34 insertions, 0 deletions

diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
index dd88646b17f..85a83bca002 100644
--- a/clang/lib/Basic/Targets.cpp
+++ b/clang/lib/Basic/Targets.cpp
@@ -2789,6 +2789,40 @@ public:
   const char *getClobbers() const override {
     return "~{dirflag},~{fpsr},~{flags}";
   }
+
+  StringRef getConstraintRegister(const StringRef &Constraint,
+                                  const StringRef &Expression) const override {
+    StringRef::iterator I, E;
+    for (I = Constraint.begin(), E = Constraint.end(); I != E; ++I) {
+      if (isalpha(*I))
+        break;
+    }
+    if (I == E)
+      return "";
+    switch (*I) {
+    // For the register constraints, return the matching register name
+    case 'a':
+      return "ax";
+    case 'b':
+      return "bx";
+    case 'c':
+      return "cx";
+    case 'd':
+      return "dx";
+    case 'S':
+      return "si";
+    case 'D':
+      return "di";
+    // In case the constraint is 'r' we need to return Expression
+    case 'r':
+      return Expression;
+    default:
+      // Default value if there is no constraint for the register
+      return "";
+    }
+    return "";
+  }
+
   void getTargetDefines(const LangOptions &Opts,
                         MacroBuilder &Builder) const override;
   static void setSSELevel(llvm::StringMap<bool> &Features, X86SSEEnum Level,