[PATCH] D75443: [AST] Unpack FPFeatures bits to BinaryOperator, NFC.

[Haojian Wu via Phabricator via cfe-commits]

hokein updated this revision to Diff 249613.
hokein marked 4 inline comments as done.
hokein added a comment.

address comments.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D75443/new/

https://reviews.llvm.org/D75443

Files:
  clang/include/clang/AST/Stmt.h
  clang/include/clang/Basic/LangOptions.h


Index: clang/include/clang/Basic/LangOptions.h
===================================================================
--- clang/include/clang/Basic/LangOptions.h
+++ clang/include/clang/Basic/LangOptions.h
@@ -356,26 +356,24 @@
 /// Floating point control options
 class FPOptions {
 public:
-  FPOptions() : fp_contract(LangOptions::FPC_Off),
-                fenv_access(LangOptions::FEA_Off),
-                rounding(LangOptions::FPR_ToNearest),
-                exceptions(LangOptions::FPE_Ignore)
-        {}
+  FPOptions()
+      : fp_contract(LangOptions::FPC_Off), fenv_access(LangOptions::FEA_Off) {
+    setRoundingAndExceptionMode(LangOptions::FPR_ToNearest,
+                                LangOptions::FPE_Ignore);
+  }
 
   // Used for serializing.
   explicit FPOptions(unsigned I)
       : fp_contract(static_cast<LangOptions::FPContractModeKind>(I & 3)),
         fenv_access(static_cast<LangOptions::FEnvAccessModeKind>((I >> 2) & 1)),
-        rounding(static_cast<LangOptions::FPRoundingModeKind>((I >> 3) & 7)),
-        exceptions(static_cast<LangOptions::FPExceptionModeKind>((I >> 6) & 3))
-        {}
+        rounding_and_exceptions(I >> 3) {}
 
   explicit FPOptions(const LangOptions &LangOpts)
       : fp_contract(LangOpts.getDefaultFPContractMode()),
-        fenv_access(LangOptions::FEA_Off),
-        rounding(LangOptions::FPR_ToNearest),
-        exceptions(LangOptions::FPE_Ignore)
-        {}
+        fenv_access(LangOptions::FEA_Off) {
+    setRoundingAndExceptionMode(LangOptions::FPR_ToNearest,
+                                LangOptions::FPE_Ignore);
+  }
   // FIXME: Use getDefaultFEnvAccessMode() when available.
 
   bool allowFPContractWithinStatement() const {
@@ -407,19 +405,19 @@
   void setDisallowFEnvAccess() { fenv_access = LangOptions::FEA_Off; }
 
   LangOptions::FPRoundingModeKind getRoundingMode() const {
-    return static_cast<LangOptions::FPRoundingModeKind>(rounding);
+     return getRoundingAndExceptionMode().first;
   }
 
   void setRoundingMode(LangOptions::FPRoundingModeKind RM) {
-    rounding = RM;
+    setRoundingAndExceptionMode(RM, getExceptionMode());
   }
 
   LangOptions::FPExceptionModeKind getExceptionMode() const {
-    return static_cast<LangOptions::FPExceptionModeKind>(exceptions);
+    return getRoundingAndExceptionMode().second;
   }
 
   void setExceptionMode(LangOptions::FPExceptionModeKind EM) {
-    exceptions = EM;
+    setRoundingAndExceptionMode(getRoundingMode(), EM);
   }
 
   bool isFPConstrained() const {
@@ -430,18 +428,37 @@
 
   /// Used to serialize this.
   unsigned getInt() const {
-    return fp_contract | (fenv_access << 2) | (rounding << 3)
-        | (exceptions << 6);
+    return fp_contract | (fenv_access << 2) | (rounding_and_exceptions << 3);
   }
 
 private:
+  void setRoundingAndExceptionMode(LangOptions::FPRoundingModeKind RM,
+                                   LangOptions::FPExceptionModeKind EM) {
+    static_assert(LangOptions::FPExceptionModeKind::FPE_Strict <
+                      MaxExceptionValue,
+                  "Max exception value must be less than 3");
+    rounding_and_exceptions = RM * MaxExceptionValue + EM;
+  }
+
+  std::pair<LangOptions::FPRoundingModeKind, LangOptions::FPExceptionModeKind>
+  getRoundingAndExceptionMode() const {
+    unsigned exceptions = rounding_and_exceptions % MaxExceptionValue;
+    unsigned rounding = rounding_and_exceptions / MaxExceptionValue;
+    return {static_cast<LangOptions::FPRoundingModeKind>(rounding),
+            static_cast<LangOptions::FPExceptionModeKind>(exceptions)};
+  }
+
+
   /// Adjust BinaryOperatorBitfields::FPFeatures and
   /// CXXOperatorCallExprBitfields::FPFeatures to match the total bit-field size
   /// of these fields.
   unsigned fp_contract : 2;
   unsigned fenv_access : 1;
-  unsigned rounding : 3;
-  unsigned exceptions : 2;
+  // A packed field for encoding rounding and exceptions.
+  // FIXME: unpack this once saving one bit isn't critical here.
+  // rounding_and_exceptions = MaxExceptionValue * rounding + exceptions.
+  constexpr static unsigned MaxExceptionValue = 3;
+  unsigned rounding_and_exceptions: 4;
 };
 
 /// Describes the kind of translation unit being processed.
Index: clang/include/clang/AST/Stmt.h
===================================================================
--- clang/include/clang/AST/Stmt.h
+++ clang/include/clang/AST/Stmt.h
@@ -531,7 +531,7 @@
 
     /// This is only meaningful for operations on floating point
     /// types and 0 otherwise.
-    unsigned FPFeatures : 8;
+    unsigned FPFeatures : 7;
 
     SourceLocation OpLoc;
   };
@@ -614,7 +614,7 @@
     unsigned OperatorKind : 6;
 
     // Only meaningful for floating point types.
-    unsigned FPFeatures : 8;
+    unsigned FPFeatures : 7;
   };
 
   class CXXRewrittenBinaryOperatorBitfields {

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