R600: Implement getRecipEstimate

This requires a new hook to prevent expanding sqrt in terms
of rsqrt and reciprocal. v_rcp_f32, v_rsq_f32, and v_sqrt_f32 are
all the same rate, so this expansion would just double the number
of instructions and cycles.

llvm-svn: 225828

1 files changed, 1 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
index fae54d2c304..9b2fdffa87c 100644
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -710,6 +710,7 @@ TargetLoweringBase::TargetLoweringBase(const TargetMachine &tm)
   HasMultipleConditionRegisters = false;
   HasExtractBitsInsn = false;
   IntDivIsCheap = false;
+  FsqrtIsCheap = false;
   Pow2SDivIsCheap = false;
   JumpIsExpensive = false;
   PredictableSelectIsExpensive = false;