[RISCV] Validate the SEW and LMUL operands to __builtin_rvv_vsetvli(max)

[craig.topper]

Summary

These are required to be constants, this patch makes sure they
are in the accepted range of values.

These are usually created by wrappers in the riscv_vector.h header
which should always be correct. This patch protects against a user
using the builtin directly.

[khchen]

Good catch, LGTM!

clang/include/clang/Basic/DiagnosticSemaKinds.td

def err_tcb_conflicting_attributes : Error<
   "attributes '%0(\"%2\")' and '%1(\"%2\")' are mutually exclusive">;
 def warn_tcb_enforcement_violation : Warning<
   "calling %0 is a violation of trusted computing base '%1'">,
   InGroup<DiagGroup<"tcb-enforcement">>;
 
 // RISC-V builtin required extension warning
 def err_riscv_builtin_requires_extension : Error<
   "builtin requires '%0' extension support to be enabled">;
+def err_riscv_builtin_invalid_lmul : Error<
+  "LMUL argument must be in the range [0,3] or [5,7]">;
 } // end of sema component.

clang/include/clang/Sema/Sema.h

private:
   bool CheckX86BuiltinTileDuplicate(CallExpr *TheCall, ArrayRef<int> ArgNums);
   bool CheckX86BuiltinTileRangeAndDuplicate(CallExpr *TheCall,
                                             ArrayRef<int> ArgNums);
   bool CheckX86BuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                    CallExpr *TheCall);
   bool CheckPPCBuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                    CallExpr *TheCall);
   bool CheckAMDGCNBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall);
+  bool CheckRISCVLMUL(CallExpr *TheCall, unsigned ArgNum);
   bool CheckRISCVBuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                      CallExpr *TheCall);
 
   bool SemaBuiltinVAStart(unsigned BuiltinID, CallExpr *TheCall);
   bool SemaBuiltinVAStartARMMicrosoft(CallExpr *Call);
   bool SemaBuiltinUnorderedCompare(CallExpr *TheCall);
   bool SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs);
   bool SemaBuiltinComplex(CallExpr *TheCall);

clang/lib/Sema/SemaChecking.cpp

bool Sema::CheckAMDGCNBuiltinFunctionCall(unsigned BuiltinID,
   // Check that sync scope is a constant literal
   if (!ArgExpr->EvaluateAsConstantExpr(ArgResult1, Context))
     return Diag(ArgExpr->getExprLoc(), diag::err_expr_not_string_literal)
            << ArgExpr->getType();
 
   return false;
 }
 
+bool Sema::CheckRISCVLMUL(CallExpr *TheCall, unsigned ArgNum) {
+  llvm::APSInt Result;
+
+  // We can't check the value of a dependent argument.
+  Expr *Arg = TheCall->getArg(ArgNum);
+  if (Arg->isTypeDependent() || Arg->isValueDependent())
+    return false;
+
+  // Check constant-ness first.
+  if (SemaBuiltinConstantArg(TheCall, ArgNum, Result))
+    return true;
+
+  int64_t Val = Result.getSExtValue();
+  if ((Val >= 0 && Val <= 3) || (Val >= 5 && Val <= 7))
+    return false;
+
+  return Diag(TheCall->getBeginLoc(), diag::err_riscv_builtin_invalid_lmul)
+         << Arg->getSourceRange();
+}
+
 bool Sema::CheckRISCVBuiltinFunctionCall(const TargetInfo &TI,
                                          unsigned BuiltinID,
                                          CallExpr *TheCall) {
   // CodeGenFunction can also detect this, but this gives a better error
   // message.
   bool FeatureMissing = false;
   SmallVector<StringRef> ReqFeatures;
   StringRef Features = Context.BuiltinInfo.getRequiredFeatures(BuiltinID);
for (StringRef F : ReqFeatures) {
     FeatureStr[0] = std::toupper(FeatureStr[0]);
 
     // Error message
     FeatureMissing = true;
     Diag(TheCall->getBeginLoc(), diag::err_riscv_builtin_requires_extension)
         << TheCall->getSourceRange() << StringRef(FeatureStr);
   }
 
-  return FeatureMissing;
+  if (FeatureMissing)
+    return true;
+
+  switch (BuiltinID) {
+  case RISCV::BI__builtin_rvv_vsetvli:
+    return SemaBuiltinConstantArgRange(TheCall, 1, 0, 3) ||
+           CheckRISCVLMUL(TheCall, 2);
+  case RISCV::BI__builtin_rvv_vsetvlimax:
+    return SemaBuiltinConstantArgRange(TheCall, 0, 0, 3) ||
+           CheckRISCVLMUL(TheCall, 1);
+  }
+
+  return false;
 }
 
 bool Sema::CheckSystemZBuiltinFunctionCall(unsigned BuiltinID,
                                            CallExpr *TheCall) {
   if (BuiltinID == SystemZ::BI__builtin_tabort) {
     Expr *Arg = TheCall->getArg(0);
     if (Optional<llvm::APSInt> AbortCode = Arg->getIntegerConstantExpr(Context))
       if (AbortCode->getSExtValue() >= 0 && AbortCode->getSExtValue() < 256)

clang/test/CodeGen/RISCV/rvv_errors.c

+// RUN: %clang_cc1 %s -triple=riscv64 -target-feature +experimental-v -fsyntax-only -verify
+
+void test() {
+  __builtin_rvv_vsetvli(1, 7, 0); // expected-error {{argument value 7 is outside the valid range [0, 3]}}
+  __builtin_rvv_vsetvlimax(-1, 0); // expected-error {{argument value 18446744073709551615 is outside the valid range [0, 3]}}
+  __builtin_rvv_vsetvli(1, 0, 4); // expected-error {{LMUL argument must be in the range [0,3] or [5,7]}}
+  __builtin_rvv_vsetvlimax(0, 4); // expected-error {{LMUL argument must be in the range [0,3] or [5,7]}}
+  __builtin_rvv_vsetvli(1, 0, 8); // expected-error {{LMUL argument must be in the range [0,3] or [5,7]}}
+  __builtin_rvv_vsetvlimax(0, -1); // expected-error {{LMUL argument must be in the range [0,3] or [5,7]}}
+}