1 files changed, 72 insertions, 0 deletions
diff --git a/llvm/test/CodeGen/X86/recip-fastmath.ll b/llvm/test/CodeGen/X86/recip-fastmath.ll
new file mode 100644
index 00000000000..dd5563c965f
--- /dev/null
+++ b/llvm/test/CodeGen/X86/recip-fastmath.ll
@@ -0,0 +1,72 @@
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=core2 | FileCheck %s
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=btver2 | FileCheck %s --check-prefix=BTVER2
+
+; If the target's divss/divps instructions are substantially
+; slower than rcpss/rcpps with a Newton-Raphson refinement,
+; we should generate the estimate sequence.
+
+; See PR21385 ( http://llvm.org/bugs/show_bug.cgi?id=21385 )
+; for details about the accuracy, speed, and implementation
+; differences of x86 reciprocal estimates.
+
+define float @reciprocal_estimate(float %x) #0 {
+  %div = fdiv fast float 1.0, %x
+  ret float %div
+
+; CHECK-LABEL: reciprocal_estimate:
+; CHECK: movss
+; CHECK-NEXT: divss
+; CHECK-NEXT: movaps
+; CHECK-NEXT: retq
+
+; BTVER2-LABEL: reciprocal_estimate:
+; BTVER2: vrcpss
+; BTVER2-NEXT: vmulss
+; BTVER2-NEXT: vsubss
+; BTVER2-NEXT: vmulss
+; BTVER2-NEXT: vaddss
+; BTVER2-NEXT: retq
+}
+
+define <4 x float> @reciprocal_estimate_v4f32(<4 x float> %x) #0 {
+  %div = fdiv fast <4 x float> <float 1.0, float 1.0, float 1.0, float 1.0>, %x
+  ret <4 x float> %div
+
+; CHECK-LABEL: reciprocal_estimate_v4f32:
+; CHECK: movaps
+; CHECK-NEXT: divps
+; CHECK-NEXT: movaps
+; CHECK-NEXT: retq
+
+; BTVER2-LABEL: reciprocal_estimate_v4f32:
+; BTVER2: vrcpps
+; BTVER2-NEXT: vmulps
+; BTVER2-NEXT: vsubps
+; BTVER2-NEXT: vmulps
+; BTVER2-NEXT: vaddps
+; BTVER2-NEXT: retq
+}
+
+define <8 x float> @reciprocal_estimate_v8f32(<8 x float> %x) #0 {
+  %div = fdiv fast <8 x float> <float 1.0, float 1.0, float 1.0, float 1.0, float 1.0, float 1.0, float 1.0, float 1.0>, %x
+  ret <8 x float> %div
+
+; CHECK-LABEL: reciprocal_estimate_v8f32:
+; CHECK: movaps
+; CHECK: movaps
+; CHECK-NEXT: divps
+; CHECK-NEXT: divps
+; CHECK-NEXT: movaps
+; CHECK-NEXT: movaps
+; CHECK-NEXT: retq
+
+; BTVER2-LABEL: reciprocal_estimate_v8f32:
+; BTVER2: vrcpps
+; BTVER2-NEXT: vmulps
+; BTVER2-NEXT: vsubps
+; BTVER2-NEXT: vmulps
+; BTVER2-NEXT: vaddps
+; BTVER2-NEXT: retq
+}
+
+attributes #0 = { "unsafe-fp-math"="true" }