[llvm] r185178 - [NVPTX] Add (1.0 / sqrt(x)) => rsqrt(x) generation when allowable by FP flags

[Justin Holewinski]

Author: jholewinski
Date: Fri Jun 28 12:58:13 2013
New Revision: 185178

URL: http://llvm.org/viewvc/llvm-project?rev=185178&view=rev
Log:
[NVPTX] Add (1.0 / sqrt(x)) => rsqrt(x) generation when allowable by FP flags

Added:
    llvm/trunk/test/CodeGen/NVPTX/rsqrt.ll
Modified:
    llvm/trunk/lib/Target/NVPTX/NVPTXInstrInfo.td

Modified: llvm/trunk/lib/Target/NVPTX/NVPTXInstrInfo.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/NVPTX/NVPTXInstrInfo.td?rev=185178&r1=185177&r2=185178&view=diff
==============================================================================
--- llvm/trunk/lib/Target/NVPTX/NVPTXInstrInfo.td (original)
+++ llvm/trunk/lib/Target/NVPTX/NVPTXInstrInfo.td Fri Jun 28 12:58:13 2013
@@ -136,7 +136,8 @@ def hasLDG : Predicate<"Subtarget.hasLDG
 def hasLDU : Predicate<"Subtarget.hasLDU()">;
 def hasGenericLdSt : Predicate<"Subtarget.hasGenericLdSt()">;
 
-def doF32FTZ : Predicate<"UseF32FTZ">;
+def doF32FTZ : Predicate<"UseF32FTZ==1">;
+def doNoF32FTZ : Predicate<"UseF32FTZ==0">;
 
 def doFMAF32      : Predicate<"doFMAF32">;
 def doFMAF32_ftz  : Predicate<"(doFMAF32 && UseF32FTZ)">;
@@ -765,6 +766,16 @@ def FDIV32ri_prec : NVPTXInst<(outs Floa
                         (fdiv Float32Regs:$a, fpimm:$b))]>,
                       Requires<[reqPTX20]>;
 
+//
+// F32 rsqrt
+//
+
+def RSQRTF32approx1r : NVPTXInst<(outs Float32Regs:$dst), (ins Float32Regs:$b),
+                       "rsqrt.approx.f32 \t$dst, $b;", []>;
+
+def: Pat<(fdiv FloatConst1, (int_nvvm_sqrt_f Float32Regs:$b)),
+         (RSQRTF32approx1r Float32Regs:$b)>,
+         Requires<[do_DIVF32_FULL, do_SQRTF32_APPROX, doNoF32FTZ]>;
 
 multiclass FPCONTRACT32<string OpcStr, Predicate Pred> {
    def rrr : NVPTXInst<(outs Float32Regs:$dst),

Added: llvm/trunk/test/CodeGen/NVPTX/rsqrt.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/NVPTX/rsqrt.ll?rev=185178&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/NVPTX/rsqrt.ll (added)
+++ llvm/trunk/test/CodeGen/NVPTX/rsqrt.ll Fri Jun 28 12:58:13 2013
@@ -0,0 +1,13 @@
+; RUN: llc < %s -march=nvptx -mcpu=sm_20 -nvptx-prec-divf32=1 -nvptx-prec-sqrtf32=0 | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v16:16:16-v32:32:32-v64:64:64-v128:128:128-n16:32:64"
+
+declare float @llvm.nvvm.sqrt.f(float)
+
+define float @foo(float %a) {
+; CHECK: rsqrt.approx.f32
+  %val = tail call float @llvm.nvvm.sqrt.f(float %a)
+  %ret = fdiv float 1.0, %val
+  ret float %ret
+}
+  
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