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

[Haojian Wu via Phabricator via cfe-commits]

hokein updated this revision to Diff 249606.
hokein added a comment.

reduce FPOption from 8 bits to 7 bits, based on the offline discussion.


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
@@ -197,7 +197,7 @@
   /// Possible rounding modes.
   enum FPRoundingModeKind {
     /// Rounding to nearest, corresponds to "round.tonearest".
-    FPR_ToNearest,
+    FPR_ToNearest = 0,
     /// Rounding toward -Inf, corresponds to "round.downward".
     FPR_Downward,
     /// Rounding toward +Inf, corresponds to "round.upward".
@@ -211,7 +211,7 @@
   /// Possible floating point exception behavior.
   enum FPExceptionModeKind {
     /// Assume that floating-point exceptions are masked.
-    FPE_Ignore,
+    FPE_Ignore = 0,
     /// Transformations do not cause new exceptions but may hide some.
     FPE_MayTrap,
     /// Strictly preserve the floating-point exception semantics.
@@ -358,23 +358,20 @@
 public:
   FPOptions() : fp_contract(LangOptions::FPC_Off),
                 fenv_access(LangOptions::FEA_Off),
-                rounding(LangOptions::FPR_ToNearest),
-                exceptions(LangOptions::FPE_Ignore)
+                packed(0)
         {}
 
   // 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))
+        packed(I >> 3)
         {}
 
   explicit FPOptions(const LangOptions &LangOpts)
       : fp_contract(LangOpts.getDefaultFPContractMode()),
         fenv_access(LangOptions::FEA_Off),
-        rounding(LangOptions::FPR_ToNearest),
-        exceptions(LangOptions::FPE_Ignore)
+        packed(0)
         {}
   // FIXME: Use getDefaultFEnvAccessMode() when available.
 
@@ -407,19 +404,24 @@
   void setDisallowFEnvAccess() { fenv_access = LangOptions::FEA_Off; }
 
   LangOptions::FPRoundingModeKind getRoundingMode() const {
+    unsigned rounding = packed / MaxExceptionValue;
     return static_cast<LangOptions::FPRoundingModeKind>(rounding);
   }
 
   void setRoundingMode(LangOptions::FPRoundingModeKind RM) {
-    rounding = RM;
+    packed = RM * MaxExceptionValue + getExceptionMode();
   }
 
   LangOptions::FPExceptionModeKind getExceptionMode() const {
+    static_assert(LangOptions::FPExceptionModeKind::FPE_Strict <
+                      MaxExceptionValue,
+                  "Max exception value must less than 3");
+    unsigned exceptions = packed % MaxExceptionValue;
     return static_cast<LangOptions::FPExceptionModeKind>(exceptions);
   }
 
   void setExceptionMode(LangOptions::FPExceptionModeKind EM) {
-    exceptions = EM;
+    packed = getRoundingMode() * MaxExceptionValue + EM;
   }
 
   bool isFPConstrained() const {
@@ -430,8 +432,7 @@
 
   /// Used to serialize this.
   unsigned getInt() const {
-    return fp_contract | (fenv_access << 2) | (rounding << 3)
-        | (exceptions << 6);
+    return fp_contract | (fenv_access << 2) | (packed << 3);
   }
 
 private:
@@ -440,8 +441,10 @@
   /// 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.
+  // packed = MaxExceptionBits * rounding + excpetions.
+  constexpr static unsigned MaxExceptionValue = 3;
+  unsigned packed: 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;
   };

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