[llvm-commits] [dragonegg] r132709 - in /dragonegg/trunk/src/x86: Target.cpp x86_builtins

[Duncan Sands]

Author: baldrick
Date: Tue Jun  7 01:44:40 2011
New Revision: 132709

URL: http://llvm.org/viewvc/llvm-project?rev=132709&view=rev
Log:
Implement rsqrtps_nr (rsqrtps with a Newton-Raphson step).

Modified:
    dragonegg/trunk/src/x86/Target.cpp
    dragonegg/trunk/src/x86/x86_builtins

Modified: dragonegg/trunk/src/x86/Target.cpp
URL: http://llvm.org/viewvc/llvm-project/dragonegg/trunk/src/x86/Target.cpp?rev=132709&r1=132708&r2=132709&view=diff
==============================================================================
--- dragonegg/trunk/src/x86/Target.cpp (original)
+++ dragonegg/trunk/src/x86/Target.cpp Tue Jun  7 01:44:40 2011
@@ -776,6 +776,20 @@
     SI->setAlignment(16);
     return true;
   }
+  case rsqrtps_nr: {
+    // rsqrtps with a Newton-Raphson step to improve accuracy:
+    //   rsqrtps_nr(x) = rsqrtps(x) * -0.5 * (rsqrtps(x) * x * rsqrtps(x) - 3.0)
+    Function *rsqrtps = Intrinsic::getDeclaration(TheModule,
+                                                  Intrinsic::x86_sse_rsqrt_ps);
+    Value *X = Ops[0]; // x
+    Value *R = Builder.CreateCall(rsqrtps, X); // rsqrtps(x)
+    Value *RHS = Builder.CreateFAdd(Builder.CreateFMul(Builder.CreateFMul(R, X),
+                                                       R),
+                                    ConstantFP::get(X->getType(), -3.0));
+    Value *LHS = Builder.CreateFMul(R, ConstantFP::get(X->getType(), -0.5));
+    Result = Builder.CreateFMul(LHS, RHS);
+    return true;
+  }
   case sqrtps_nr: {
     // Turn this into sqrtps without a Newton-Raphson step - sqrtps is already
     // accurate enough.

Modified: dragonegg/trunk/src/x86/x86_builtins
URL: http://llvm.org/viewvc/llvm-project/dragonegg/trunk/src/x86/x86_builtins?rev=132709&r1=132708&r2=132709&view=diff
==============================================================================
--- dragonegg/trunk/src/x86/x86_builtins (original)
+++ dragonegg/trunk/src/x86/x86_builtins Tue Jun  7 01:44:40 2011
@@ -515,7 +515,7 @@
 //DEFINE_BUILTIN(rsqrtf),
 //DEFINE_BUILTIN(rsqrtps),
 //DEFINE_BUILTIN(rsqrtps256),
-//DEFINE_BUILTIN(rsqrtps_nr),
+DEFINE_BUILTIN(rsqrtps_nr),
 //DEFINE_BUILTIN(rsqrtps_nr256),
 //DEFINE_BUILTIN(rsqrtss),
 //DEFINE_BUILTIN(sfence),