Revert "Reapply "Add support for #pragma float_control" with improvements to"

This reverts commit 69aacaf.

Author: Melanie Blower

clang/docs/LanguageExtensions.rst

@@ -3197,41 +3197,6 @@ The pragma can also be used with ``off`` which turns FP contraction off for a
 section of the code. This can be useful when fast contraction is otherwise
 enabled for the translation unit with the ``-ffp-contract=fast`` flag.
 
-The ``#pragma float_control`` pragma allows precise floating-point
-semantics and floating-point exception behavior to be specified
-for a section of the source code. This pragma can only appear at file scope or
-at the start of a compound statement (excluding comments). When using within a
-compound statement, the pragma is active within the scope of the compound
-statement.  This pragma is modeled after a Microsoft pragma with the
-same spelling and syntax.  For pragmas specified at file scope, a stack
-is supported so that the ``pragma float_control`` settings can be pushed or popped.
-
-When ``pragma float_control(precise, on)`` is enabled, the section of code
-governed by the pragma uses precise floating point semantics, effectively
-``-ffast-math`` is disabled and ``-ffp-contract=on``
-(fused multiply add) is enabled.
-
-When ``pragma float_control(except, on)`` is enabled, the section of code governed
-by the pragma behaves as though the command-line option
-``-ffp-exception-behavior=strict`` is enabled,
-when ``pragma float_control(precise, off)`` is enabled, the section of code
-governed by the pragma behaves as though the command-line option
-``-ffp-exception-behavior=ignore`` is enabled.
-
-The full syntax this pragma supports is
-``float_control(except|precise, on|off [, push])`` and
-``float_control(push|pop)``.
-The ``push`` and ``pop`` forms, including using ``push`` as the optional
-third argument, can only occur at file scope.
-
-.. code-block:: c++
-
-  for(...) {
-    // This block will be compiled with -fno-fast-math and -ffp-contract=on
-    #pragma float_control(precise, on)
-    a = b[i] * c[i] + e;
-  }
-
 Specifying an attribute for multiple declarations (#pragma clang attribute)
 ===========================================================================
 

clang/include/clang/AST/Expr.h

@@ -2107,48 +2107,26 @@ class ParenExpr : public Expr {
 ///   applied to a non-complex value, the former returns its operand and the
 ///   later returns zero in the type of the operand.
 ///
-class UnaryOperator final
-    : public Expr,
-      private llvm::TrailingObjects<UnaryOperator, FPOptions> {
+class UnaryOperator : public Expr {
   Stmt *Val;
 
-  size_t numTrailingObjects(OverloadToken<FPOptions>) const {
-    return UnaryOperatorBits.HasFPFeatures ? 1 : 0;
-  }
-
-  FPOptions &getTrailingFPFeatures() {
-    assert(UnaryOperatorBits.HasFPFeatures);
-    return *getTrailingObjects<FPOptions>();
-  }
-
-  const FPOptions &getTrailingFPFeatures() const {
-    assert(UnaryOperatorBits.HasFPFeatures);
-    return *getTrailingObjects<FPOptions>();
-  }
-
 public:
   typedef UnaryOperatorKind Opcode;
 
-protected:
-  UnaryOperator(const ASTContext &Ctx, Expr *input, Opcode opc, QualType type,
-                ExprValueKind VK, ExprObjectKind OK, SourceLocation l,
-                bool CanOverflow, FPOptions FPFeatures);
+  UnaryOperator(Expr *input, Opcode opc, QualType type, ExprValueKind VK,
+                ExprObjectKind OK, SourceLocation l, bool CanOverflow)
+      : Expr(UnaryOperatorClass, type, VK, OK), Val(input) {
+    UnaryOperatorBits.Opc = opc;
+    UnaryOperatorBits.CanOverflow = CanOverflow;
+    UnaryOperatorBits.Loc = l;
+    setDependence(computeDependence(this));
+  }
 
   /// Build an empty unary operator.
-  explicit UnaryOperator(bool HasFPFeatures, EmptyShell Empty)
-      : Expr(UnaryOperatorClass, Empty) {
+  explicit UnaryOperator(EmptyShell Empty) : Expr(UnaryOperatorClass, Empty) {
     UnaryOperatorBits.Opc = UO_AddrOf;
-    UnaryOperatorBits.HasFPFeatures = HasFPFeatures;
   }
 
-public:
-  static UnaryOperator *CreateEmpty(const ASTContext &C, bool hasFPFeatures);
-
-  static UnaryOperator *Create(const ASTContext &C, Expr *input, Opcode opc,
-                               QualType type, ExprValueKind VK,
-                               ExprObjectKind OK, SourceLocation l,
-                               bool CanOverflow, FPOptions FPFeatures);
-
   Opcode getOpcode() const {
     return static_cast<Opcode>(UnaryOperatorBits.Opc);
   }
@@ -2170,18 +2148,6 @@ class UnaryOperator final
   bool canOverflow() const { return UnaryOperatorBits.CanOverflow; }
   void setCanOverflow(bool C) { UnaryOperatorBits.CanOverflow = C; }
 
-  // Get the FP contractability status of this operator. Only meaningful for
-  // operations on floating point types.
-  bool isFPContractableWithinStatement(const LangOptions &LO) const {
-    return getFPFeatures(LO).allowFPContractWithinStatement();
-  }
-
-  // Get the FENV_ACCESS status of this operator. Only meaningful for
-  // operations on floating point types.
-  bool isFEnvAccessOn(const LangOptions &LO) const {
-    return getFPFeatures(LO).allowFEnvAccess();
-  }
-
   /// isPostfix - Return true if this is a postfix operation, like x++.
   static bool isPostfix(Opcode Op) {
     return Op == UO_PostInc || Op == UO_PostDec;
@@ -2248,30 +2214,6 @@ class UnaryOperator final
   const_child_range children() const {
     return const_child_range(&Val, &Val + 1);
   }
-
-  /// Is FPFeatures in Trailing Storage?
-  bool hasStoredFPFeatures() const { return UnaryOperatorBits.HasFPFeatures; }
-
-protected:
-  /// Get FPFeatures from trailing storage
-  FPOptions getStoredFPFeatures() const { return getTrailingFPFeatures(); }
-
-  /// Set FPFeatures in trailing storage, used only by Serialization
-  void setStoredFPFeatures(FPOptions F) { getTrailingFPFeatures() = F; }
-
-public:
-  // Get the FP features status of this operator. Only meaningful for
-  // operations on floating point types.
-  FPOptions getFPFeatures(const LangOptions &LO) const {
-    if (UnaryOperatorBits.HasFPFeatures)
-      return getStoredFPFeatures();
-    return FPOptions::defaultWithoutTrailingStorage(LO);
-  }
-
-  friend TrailingObjects;
-  friend class ASTReader;
-  friend class ASTStmtReader;
-  friend class ASTStmtWriter;
 };
 
 /// Helper class for OffsetOfExpr.

clang/include/clang/AST/Stmt.h

@@ -427,11 +427,6 @@ class alignas(void *) Stmt {
 
     unsigned Opc : 5;
     unsigned CanOverflow : 1;
-    //
-    /// This is only meaningful for operations on floating point
-    /// types when additional values need to be in trailing storage.
-    /// It is 0 otherwise.
-    unsigned HasFPFeatures : 1;
 
     SourceLocation Loc;
   };
@@ -615,7 +610,7 @@ class alignas(void *) Stmt {
     unsigned OperatorKind : 6;
 
     // Only meaningful for floating point types.
-    unsigned FPFeatures : 14;
+    unsigned FPFeatures : 8;
   };
 
   class CXXRewrittenBinaryOperatorBitfields {

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -1097,9 +1097,9 @@ def warn_pragma_init_seg_unsupported_target : Warning<
   "'#pragma init_seg' is only supported when targeting a "
   "Microsoft environment">,
   InGroup<IgnoredPragmas>;
-// - #pragma restricted to file scope or start of compound statement
-def err_pragma_file_or_compound_scope : Error<
-  "'#pragma %0' can only appear at file scope or at the start of a "
+// - #pragma fp_contract
+def err_pragma_fp_contract_scope : Error<
+  "'#pragma fp_contract' can only appear at file scope or at the start of a "
   "compound statement">;
 // - #pragma stdc unknown
 def ext_stdc_pragma_ignored : ExtWarn<"unknown pragma in STDC namespace">,
@@ -1118,10 +1118,6 @@ def warn_pragma_comment_ignored : Warning<"'#pragma comment %0' ignored">,
 def err_pragma_detect_mismatch_malformed : Error<
   "pragma detect_mismatch is malformed; it requires two comma-separated "
   "string literals">;
-// - #pragma float_control
-def err_pragma_float_control_malformed : Error<
-  "pragma float_control is malformed; use 'float_control({push|pop})' or "
-  "'float_control({precise|except}, {on|off} [,push])'">;
 // - #pragma pointers_to_members
 def err_pragma_pointers_to_members_unknown_kind : Error<
   "unexpected %0, expected to see one of %select{|'best_case', 'full_generality', }1"
@@ -1336,6 +1332,9 @@ def err_pragma_fp_invalid_option : Error<
 def err_pragma_fp_invalid_argument : Error<
   "unexpected argument '%0' to '#pragma clang fp %1'; "
   "expected 'on', 'fast' or 'off'">;
+def err_pragma_fp_scope : Error<
+  "'#pragma clang fp' can only appear at file scope or at the start of a "
+  "compound statement">;
 
 def err_pragma_invalid_keyword : Error<
   "invalid argument; expected 'enable'%select{|, 'full'}0%select{|, 'assume_safety'}1 or 'disable'">;

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -858,16 +858,6 @@ def warn_pragma_pack_pop_identifier_and_alignment : Warning<
   "specifying both a name and alignment to 'pop' is undefined">;
 def warn_pragma_pop_failed : Warning<"#pragma %0(pop, ...) failed: %1">,
   InGroup<IgnoredPragmas>;
-def err_pragma_fc_pp_scope : Error<
-  "'#pragma float_control push/pop' can only appear at file scope">;
-def err_pragma_fc_noprecise_requires_nofenv : Error<
-  "'#pragma float_control(precise, off)' is illegal when fenv_access is enabled">;
-def err_pragma_fc_except_requires_precise : Error<
-  "'#pragma float_control(except, on)' is illegal when precise is disabled">;
-def err_pragma_fc_noprecise_requires_noexcept : Error<
-  "'#pragma float_control(precise, off)' is illegal when except is enabled">;
-def err_pragma_fenv_requires_precise : Error<
-  "'#pragma STDC FENV_ACCESS ON' is illegal when precise is disabled">;
 def warn_cxx_ms_struct :
   Warning<"ms_struct may not produce Microsoft-compatible layouts for classes "
           "with base classes or virtual functions">,

clang/include/clang/Basic/LangOptions.def

@@ -191,12 +191,6 @@ COMPATIBLE_LANGOPT(Deprecated        , 1, 0, "__DEPRECATED predefined macro")
 COMPATIBLE_LANGOPT(FastMath          , 1, 0, "fast FP math optimizations, and __FAST_MATH__ predefined macro")
 COMPATIBLE_LANGOPT(FiniteMathOnly    , 1, 0, "__FINITE_MATH_ONLY__ predefined macro")
 COMPATIBLE_LANGOPT(UnsafeFPMath      , 1, 0, "Unsafe Floating Point Math")
-COMPATIBLE_LANGOPT(AllowFPReassoc    , 1, 0, "Permit Floating Point reassociation")
-COMPATIBLE_LANGOPT(NoHonorNaNs       , 1, 0, "Permit Floating Point optimization without regard to NaN")
-COMPATIBLE_LANGOPT(NoHonorInfs       , 1, 0, "Permit Floating Point optimization without regard to infinities")
-COMPATIBLE_LANGOPT(NoSignedZero      , 1, 0, "Permit Floating Point optimization without regard to signed zeros")
-COMPATIBLE_LANGOPT(AllowRecip        , 1, 0, "Permit Floating Point reciprocal")
-COMPATIBLE_LANGOPT(ApproxFunc        , 1, 0, "Permit Floating Point approximation")
 
 BENIGN_LANGOPT(ObjCGCBitmapPrint , 1, 0, "printing of GC's bitmap layout for __weak/__strong ivars")
 

clang/include/clang/Basic/LangOptions.h

@@ -304,8 +304,6 @@ class LangOptions : public LangOptionsBase {
   /// input is a header file (i.e. -x c-header).
   bool IsHeaderFile = false;
 
-  bool denormalIsIEEE = false;
-
   LangOptions();
 
   // Define accessors/mutators for language options of enumeration type.
@@ -379,33 +377,28 @@ class FPOptions {
   using RoundingMode = llvm::RoundingMode;
 
 public:
-  FPOptions()
-      : fp_contract(LangOptions::FPC_Off), fenv_access(LangOptions::FEA_Off),
-        rounding(LangOptions::FPR_ToNearest),
-        exceptions(LangOptions::FPE_Ignore), allow_reassoc(0), no_nans(0),
-        no_infs(0), no_signed_zeros(0), allow_reciprocal(0), approx_func(0) {}
+  FPOptions() : fp_contract(LangOptions::FPC_Off),
+                fenv_access(LangOptions::FEA_Off),
+                rounding(LangOptions::FPR_ToNearest),
+                exceptions(LangOptions::FPE_Ignore)
+        {}
 
   // Used for serializing.
-  explicit FPOptions(unsigned I) { getFromOpaqueInt(I); }
+  explicit FPOptions(unsigned I)
+      : fp_contract(I & 3),
+        fenv_access((I >> 2) & 1),
+        rounding   ((I >> 3) & 7),
+        exceptions ((I >> 6) & 3)
+        {}
 
   explicit FPOptions(const LangOptions &LangOpts)
       : fp_contract(LangOpts.getDefaultFPContractMode()),
         fenv_access(LangOptions::FEA_Off),
-        rounding(static_cast<unsigned>(LangOpts.getFPRoundingMode())),
-        exceptions(LangOpts.getFPExceptionMode()),
-        allow_reassoc(LangOpts.FastMath || LangOpts.AllowFPReassoc),
-        no_nans(LangOpts.FastMath || LangOpts.NoHonorNaNs),
-        no_infs(LangOpts.FastMath || LangOpts.NoHonorInfs),
-        no_signed_zeros(LangOpts.FastMath || LangOpts.NoSignedZero),
-        allow_reciprocal(LangOpts.FastMath || LangOpts.AllowRecip),
-        approx_func(LangOpts.FastMath || LangOpts.ApproxFunc) {}
+        rounding(LangOptions::FPR_ToNearest),
+        exceptions(LangOptions::FPE_Ignore)
+        {}
   // FIXME: Use getDefaultFEnvAccessMode() when available.
 
-  void setFastMath(bool B = true) {
-    allow_reassoc = no_nans = no_infs = no_signed_zeros = approx_func =
-        allow_reciprocal = B;
-  }
-
   /// Return the default value of FPOptions that's used when trailing
   /// storage isn't required.
   static FPOptions defaultWithoutTrailingStorage(const LangOptions &LO);
@@ -440,18 +433,6 @@ class FPOptions {
     fenv_access = LangOptions::FEA_On;
   }
 
-  void setFPPreciseEnabled(bool Value) {
-    if (Value) {
-      /* Precise mode implies fp_contract=on and disables ffast-math */
-      setFastMath(false);
-      setAllowFPContractWithinStatement();
-    } else {
-      /* Precise mode implies fp_contract=fast and enables ffast-math */
-      setFastMath(true);
-      setAllowFPContractAcrossStatement();
-    }
-  }
-
   void setDisallowFEnvAccess() { fenv_access = LangOptions::FEA_Off; }
 
   RoundingMode getRoundingMode() const {
@@ -470,22 +451,6 @@ class FPOptions {
     exceptions = EM;
   }
 
-  /// FMF Flag queries
-  bool allowAssociativeMath() const { return allow_reassoc; }
-  bool noHonorNaNs() const { return no_nans; }
-  bool noHonorInfs() const { return no_infs; }
-  bool noSignedZeros() const { return no_signed_zeros; }
-  bool allowReciprocalMath() const { return allow_reciprocal; }
-  bool allowApproximateFunctions() const { return approx_func; }
-
-  /// Flag setters
-  void setAllowAssociativeMath(bool B = true) { allow_reassoc = B; }
-  void setNoHonorNaNs(bool B = true) { no_nans = B; }
-  void setNoHonorInfs(bool B = true) { no_infs = B; }
-  void setNoSignedZeros(bool B = true) { no_signed_zeros = B; }
-  void setAllowReciprocalMath(bool B = true) { allow_reciprocal = B; }
-  void setAllowApproximateFunctions(bool B = true) { approx_func = B; }
-
   bool isFPConstrained() const {
     return getRoundingMode() != RoundingMode::NearestTiesToEven ||
            getExceptionMode() != LangOptions::FPE_Ignore ||
@@ -495,23 +460,7 @@ class FPOptions {
   /// Used to serialize this.
   unsigned getAsOpaqueInt() const {
     return fp_contract | (fenv_access << 2) | (rounding << 3) |
-           (exceptions << 6) | (allow_reassoc << 8) | (no_nans << 9) |
-           (no_infs << 10) | (no_signed_zeros << 11) |
-           (allow_reciprocal << 12) | (approx_func << 13);
-  }
-
-  /// Used with getAsOpaqueInt() to manage the float_control pragma stack.
-  void getFromOpaqueInt(unsigned I) {
-    fp_contract = (static_cast<LangOptions::FPContractModeKind>(I & 3));
-    fenv_access = (static_cast<LangOptions::FEnvAccessModeKind>((I >> 2) & 1));
-    rounding = static_cast<unsigned>(static_cast<RoundingMode>((I >> 3) & 7));
-    exceptions = (static_cast<LangOptions::FPExceptionModeKind>((I >> 6) & 3));
-    allow_reassoc = ((I >> 8) & 1);
-    no_nans = ((I >> 9) & 1);
-    no_infs = ((I >> 10) & 1);
-    no_signed_zeros = ((I >> 11) & 1);
-    allow_reciprocal = ((I >> 12) & 1);
-    approx_func = ((I >> 13) & 1);
+           (exceptions << 6);
   }
 
 private:
@@ -522,25 +471,6 @@ class FPOptions {
   unsigned fenv_access : 1;
   unsigned rounding : 3;
   unsigned exceptions : 2;
-  /// Allow reassociation transformations for floating-point instructions.
-  unsigned allow_reassoc : 1;
-  /// No NaNs - Allow optimizations to assume the arguments and result
-  /// are not NaN. If an argument is a nan, or the result would be a nan,
-  /// it produces a :ref:`poison value <poisonvalues>` instead.
-  unsigned no_nans : 1;
-  /// No Infs - Allow optimizations to assume the arguments and result
-  /// are not +/-Inf. If an argument is +/-Inf, or the result would be +/-Inf,
-  /// it produces a :ref:`poison value <poisonvalues>` instead.
-  unsigned no_infs : 1;
-  /// No Signed Zeros - Allow optimizations to treat the sign of a zero
-  /// argument or result as insignificant.
-  unsigned no_signed_zeros : 1;
-  /// Allow Reciprocal - Allow optimizations to use the reciprocal
-  /// of an argument rather than perform division.
-  unsigned allow_reciprocal : 1;
-  /// Approximate functions - Allow substitution of approximate calculations
-  /// for functions (sin, log, sqrt, etc).
-  unsigned approx_func : 1;
 };
 
 /// Describes the kind of translation unit being processed.