[InstCombine] add tests for 'afn' FMF; NFC

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@318423 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstCombine/pow-sqrt.ll

@@ -19,6 +19,27 @@ define double @pow_neghalf(double %x) {
   ret double %pow
 }
 
+define double @pow_half_approx(double %x) {
+; CHECK-LABEL: @pow_half_approx(
+; CHECK-NEXT:    [[SQRT:%.*]] = call double @sqrt(double %x) #1
+; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.fabs.f64(double [[SQRT]])
+; CHECK-NEXT:    [[TMP2:%.*]] = fcmp oeq double %x, 0xFFF0000000000000
+; CHECK-NEXT:    [[TMP3:%.*]] = select i1 [[TMP2]], double 0x7FF0000000000000, double [[TMP1]]
+; CHECK-NEXT:    ret double [[TMP3]]
+;
+  %pow = call afn double @llvm.pow.f64(double %x, double 5.000000e-01)
+  ret double %pow
+}
+
+define double @pow_neghalf_approx(double %x) {
+; CHECK-LABEL: @pow_neghalf_approx(
+; CHECK-NEXT:    [[POW:%.*]] = call afn double @llvm.pow.f64(double %x, double -5.000000e-01)
+; CHECK-NEXT:    ret double [[POW]]
+;
+  %pow = call afn double @llvm.pow.f64(double %x, double -5.000000e-01)
+  ret double %pow
+}
+
 declare double @llvm.pow.f64(double, double) #0
 
 attributes #0 = { nounwind readnone speculatable }