Fix inline assembler constraint validation

The current constraint logic is both too lax and too strict. It fails
for input outside the [INT_MIN..INT_MAX] range, but it also implicitly
accepts 0 as value when it should not. Adjust logic to handle both
correctly.

Differential Revision: https://reviews.llvm.org/D58649


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@354937 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/TargetInfo.h

@@ -816,6 +816,7 @@ class TargetInfo : public virtual TransferrableTargetInfo,
     struct {
       int Min;
       int Max;
+      bool isConstrained;
     } ImmRange;
     llvm::SmallSet<int, 4> ImmSet;
 
@@ -826,6 +827,7 @@ class TargetInfo : public virtual TransferrableTargetInfo,
         : Flags(0), TiedOperand(-1), ConstraintStr(ConstraintStr.str()),
           Name(Name.str()) {
       ImmRange.Min = ImmRange.Max = 0;
+      ImmRange.isConstrained = false;
     }
 
     const std::string &getConstraintStr() const { return ConstraintStr; }
@@ -854,8 +856,9 @@ class TargetInfo : public virtual TransferrableTargetInfo,
       return (Flags & CI_ImmediateConstant) != 0;
     }
     bool isValidAsmImmediate(const llvm::APInt &Value) const {
-      return (Value.sge(ImmRange.Min) && Value.sle(ImmRange.Max)) ||
-             ImmSet.count(Value.getZExtValue()) != 0;
+      if (!ImmSet.empty())
+        return ImmSet.count(Value.getZExtValue()) != 0;
+      return !ImmRange.isConstrained || (Value.sge(ImmRange.Min) && Value.sle(ImmRange.Max));
     }
 
     void setIsReadWrite() { Flags |= CI_ReadWrite; }
@@ -867,6 +870,7 @@ class TargetInfo : public virtual TransferrableTargetInfo,
       Flags |= CI_ImmediateConstant;
       ImmRange.Min = Min;
       ImmRange.Max = Max;
+      ImmRange.isConstrained = true;
     }
     void setRequiresImmediate(llvm::ArrayRef<int> Exacts) {
       Flags |= CI_ImmediateConstant;
@@ -879,8 +883,6 @@ class TargetInfo : public virtual TransferrableTargetInfo,
     }
     void setRequiresImmediate() {
       Flags |= CI_ImmediateConstant;
-      ImmRange.Min = INT_MIN;
-      ImmRange.Max = INT_MAX;
     }
 
     /// Indicate that this is an input operand that is tied to

test/Sema/inline-asm-validate-x86.c

@@ -55,6 +55,7 @@ void K(int i, int j) {
 void L(int i, int j) {
   static const int Invalid1 = 1;
   static const int Invalid2 = 42;
+  static const int Invalid3 = 0;
   static const int Valid1 = 0xff;
   static const int Valid2 = 0xffff;
   static const int Valid3 = 0xffffffff;
@@ -67,6 +68,9 @@ void L(int i, int j) {
   __asm__("xorl %0,%2"
           : "=r"(i)
           : "0"(i), "L"(Invalid2)); // expected-error{{value '42' out of range for constraint 'L'}}
+  __asm__("xorl %0,%2"
+          : "=r"(i)
+          : "0"(i), "L"(Invalid3)); // expected-error{{value '0' out of range for constraint 'L'}}
   __asm__("xorl %0,%2"
           : "=r"(i)
           : "0"(i), "L"(Valid1)); // expected-no-error