We have in place support for parsing #pragma FENV_ACCESS, but that

information is then discarded with a warning to the user that we don't 
support it.

This patch gets us one step closer by getting the info down into the 
AST in most cases.

Reviewed by:	rsmith
Differential Revision:	https://reviews.llvm.org/D49865

llvm-svn: 339693

clang/include/clang/AST/Expr.h

@@ -3269,7 +3269,7 @@ private:
 
   // This is only meaningful for operations on floating point types and 0
   // otherwise.
-  unsigned FPFeatures : 2;
+  unsigned FPFeatures : 3;
   SourceLocation OpLoc;
 
   enum { LHS, RHS, END_EXPR };
@@ -3448,6 +3448,12 @@ public:
     return FPOptions(FPFeatures).allowFPContractWithinStatement();
   }
 
+  // Get the FENV_ACCESS status of this operator. Only meaningful for
+  // operations on floating point types.
+  bool isFEnvAccessOn() const {
+    return FPOptions(FPFeatures).allowFEnvAccess();
+  }
+
 protected:
   BinaryOperator(Expr *lhs, Expr *rhs, Opcode opc, QualType ResTy,
                  ExprValueKind VK, ExprObjectKind OK,

clang/include/clang/Basic/LangOptions.h

@@ -137,6 +137,14 @@ public:
     FPC_Fast
   };
 
+  // TODO: merge FEnvAccessModeKind and FPContractModeKind
+  enum FEnvAccessModeKind {
+    FEA_Off,
+
+    FEA_On
+  };
+
+
 public:
   /// Set of enabled sanitizers.
   SanitizerSet Sanitize;
@@ -262,14 +270,19 @@ public:
 /// Floating point control options
 class FPOptions {
 public:
-  FPOptions() : fp_contract(LangOptions::FPC_Off) {}
+  FPOptions() : fp_contract(LangOptions::FPC_Off), 
+                fenv_access(LangOptions::FEA_Off) {}
 
   // Used for serializing.
   explicit FPOptions(unsigned I)
-      : fp_contract(static_cast<LangOptions::FPContractModeKind>(I)) {}
+      : fp_contract(static_cast<LangOptions::FPContractModeKind>(I & 3)),
+        fenv_access(static_cast<LangOptions::FEnvAccessModeKind>((I >> 2) & 1))
+        {}
 
   explicit FPOptions(const LangOptions &LangOpts)
-      : fp_contract(LangOpts.getDefaultFPContractMode()) {}
+      : fp_contract(LangOpts.getDefaultFPContractMode()),
+        fenv_access(LangOptions::FEA_Off) {}
+  // FIXME: Use getDefaultFEnvAccessMode() when available.
 
   bool allowFPContractWithinStatement() const {
     return fp_contract == LangOptions::FPC_On;
@@ -289,12 +302,24 @@ public:
 
   void setDisallowFPContract() { fp_contract = LangOptions::FPC_Off; }
 
+  bool allowFEnvAccess() const {
+    return fenv_access == LangOptions::FEA_On;
+  }
+
+  void setAllowFEnvAccess() {
+    fenv_access = LangOptions::FEA_On;
+  }
+
+  void setDisallowFEnvAccess() { fenv_access = LangOptions::FEA_Off; }
+
   /// Used to serialize this.
-  unsigned getInt() const { return fp_contract; }
+  unsigned getInt() const { return fp_contract | (fenv_access << 2); }
 
 private:
-  /// Adjust BinaryOperator::FPFeatures to match the bit-field size of this.
+  /// Adjust BinaryOperator::FPFeatures to match the total bit-field size 
+  /// of these two.
   unsigned fp_contract : 2;
+  unsigned fenv_access : 1;
 };
 
 /// Describes the kind of translation unit being processed.

clang/include/clang/Basic/TokenKinds.def

@@ -780,6 +780,11 @@ ANNOTATION(pragma_redefine_extname)
 // handles them.
 ANNOTATION(pragma_fp_contract)
 
+// Annotation for #pragma STDC FENV_ACCESS
+// The lexer produces these so that they only take effect when the parser
+// handles them.
+ANNOTATION(pragma_fenv_access)
+
 // Annotation for #pragma pointers_to_members...
 // The lexer produces these so that they only take effect when the parser
 // handles them.

clang/include/clang/Parse/Parser.h

@@ -670,6 +670,10 @@ private:
   void HandlePragmaFPContract();
 
   /// Handle the annotation token produced for
+  /// #pragma STDC FENV_ACCESS...
+  void HandlePragmaFEnvAccess();
+
+  /// \brief Handle the annotation token produced for
   /// #pragma clang fp ...
   void HandlePragmaFP();
 

clang/include/clang/Sema/Sema.h

@@ -8434,6 +8434,10 @@ public:
   /// \#pragma clang fp contract
   void ActOnPragmaFPContract(LangOptions::FPContractModeKind FPC);
 
+  /// ActOnPragmaFenvAccess - Called on well formed
+  /// \#pragma STDC FENV_ACCESS
+  void ActOnPragmaFEnvAccess(LangOptions::FEnvAccessModeKind FPC);
+
   /// AddAlignmentAttributesForRecord - Adds any needed alignment attributes to
   /// a the record decl, to handle '\#pragma pack' and '\#pragma options align'.
   void AddAlignmentAttributesForRecord(RecordDecl *RD);

clang/lib/Parse/ParsePragma.cpp

@@ -106,8 +106,19 @@ struct PragmaSTDC_FENV_ACCESSHandler : public PragmaHandler {
     tok::OnOffSwitch OOS;
     if (PP.LexOnOffSwitch(OOS))
      return;
-    if (OOS == tok::OOS_ON)
+    if (OOS == tok::OOS_ON) {
       PP.Diag(Tok, diag::warn_stdc_fenv_access_not_supported);
+    }
+
+    MutableArrayRef<Token> Toks(PP.getPreprocessorAllocator().Allocate<Token>(1),
+                                1);
+    Toks[0].startToken();
+    Toks[0].setKind(tok::annot_pragma_fenv_access);
+    Toks[0].setLocation(Tok.getLocation());
+    Toks[0].setAnnotationEndLoc(Tok.getLocation());
+    Toks[0].setAnnotationValue(reinterpret_cast<void*>(
+                               static_cast<uintptr_t>(OOS)));
+    PP.EnterTokenStream(Toks, /*DisableMacroExpansion=*/true);
   }
 };
 
@@ -604,6 +615,30 @@ void Parser::HandlePragmaFPContract() {
   ConsumeAnnotationToken();
 }
 
+void Parser::HandlePragmaFEnvAccess() {
+  assert(Tok.is(tok::annot_pragma_fenv_access));
+  tok::OnOffSwitch OOS =
+    static_cast<tok::OnOffSwitch>(
+    reinterpret_cast<uintptr_t>(Tok.getAnnotationValue()));
+
+  LangOptions::FEnvAccessModeKind FPC;
+  switch (OOS) {
+  case tok::OOS_ON:
+    FPC = LangOptions::FEA_On;
+    break;
+  case tok::OOS_OFF:
+    FPC = LangOptions::FEA_Off;
+    break;
+  case tok::OOS_DEFAULT: // FIXME: Add this cli option when it makes sense.
+    FPC = LangOptions::FEA_Off;
+    break;
+  }
+
+  Actions.ActOnPragmaFEnvAccess(FPC);
+  ConsumeAnnotationToken();
+}
+
+
 StmtResult Parser::HandlePragmaCaptured()
 {
   assert(Tok.is(tok::annot_pragma_captured));

clang/lib/Parse/ParseStmt.cpp

@@ -348,6 +348,11 @@ Retry:
     ConsumeAnnotationToken();
     return StmtError();
 
+  case tok::annot_pragma_fenv_access:
+    ProhibitAttributes(Attrs);
+    HandlePragmaFEnvAccess();
+    return StmtEmpty();
+
   case tok::annot_pragma_opencl_extension:
     ProhibitAttributes(Attrs);
     HandlePragmaOpenCLExtension();
@@ -902,6 +907,9 @@ void Parser::ParseCompoundStatementLeadingPragmas() {
     case tok::annot_pragma_fp:
       HandlePragmaFP();
       break;
+    case tok::annot_pragma_fenv_access:
+      HandlePragmaFEnvAccess();
+      break;
     case tok::annot_pragma_ms_pointers_to_members:
       HandlePragmaMSPointersToMembers();
       break;

clang/lib/Parse/Parser.cpp

@@ -674,6 +674,9 @@ Parser::ParseExternalDeclaration(ParsedAttributesWithRange &attrs,
   case tok::annot_pragma_fp_contract:
     HandlePragmaFPContract();
     return nullptr;
+  case tok::annot_pragma_fenv_access:
+    HandlePragmaFEnvAccess();
+    return nullptr;
   case tok::annot_pragma_fp:
     HandlePragmaFP();
     break;

clang/lib/Sema/SemaAttr.cpp

@@ -773,6 +773,18 @@ void Sema::ActOnPragmaFPContract(LangOptions::FPContractModeKind FPC) {
   }
 }
 
+void Sema::ActOnPragmaFEnvAccess(LangOptions::FEnvAccessModeKind FPC) {
+  switch (FPC) {
+  case LangOptions::FEA_On:
+    FPFeatures.setAllowFEnvAccess();
+    break;
+  case LangOptions::FEA_Off:
+    FPFeatures.setDisallowFEnvAccess();
+    break;
+  }
+}
+
+
 void Sema::PushNamespaceVisibilityAttr(const VisibilityAttr *Attr,
                                        SourceLocation Loc) {
   // Visibility calculations will consider the namespace's visibility.