Use rsqrt (X86) to speed up reciprocal square root calcs

[oota-llvm.git] / lib / Target / X86 / X86Subtarget.h

diff --git a/lib/Target/X86/X86Subtarget.h b/lib/Target/X86/X86Subtarget.h
index 24ee5538347db7394f6091a3fce59b050c1dc2ae..cdecf2a9cb27c4a9217dcccafd4301417a21a3e0 100644 (file)
--- a/lib/Target/X86/X86Subtarget.h
+++ b/lib/Target/X86/X86Subtarget.h
@@ -192,6 +192,11 @@ protected:
   /// SlowIncDec - True if INC and DEC instructions are slow when writing to flags
   bool SlowIncDec;
 
+  /// Use the RSQRT* instructions to optimize square root calculations.
+  /// For this to be profitable, the cost of FSQRT and FDIV must be
+  /// substantially higher than normal FP ops like FADD and FMUL.
+  bool UseSqrtEst;
+
   /// Processor has AVX-512 PreFetch Instructions
   bool HasPFI;
 
@@ -369,6 +374,7 @@ public:
   bool LEAusesAG() const { return LEAUsesAG; }
   bool slowLEA() const { return SlowLEA; }
   bool slowIncDec() const { return SlowIncDec; }
+  bool useSqrtEst() const { return UseSqrtEst; }
   bool hasCDI() const { return HasCDI; }
   bool hasPFI() const { return HasPFI; }
   bool hasERI() const { return HasERI; }