Transform pow(x, 0.5) to (x == -inf ? inf : fabs(sqrt(x))), which is

typically faster then doing a general pow.

llvm-svn: 82819

1 files changed, 33 insertions, 0 deletions

diff --git a/llvm/test/Transforms/SimplifyLibCalls/pow-to-sqrt.ll b/llvm/test/Transforms/SimplifyLibCalls/pow-to-sqrt.ll
new file mode 100644
index 00000000000..cb4abc1709a
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyLibCalls/pow-to-sqrt.ll
@@ -0,0 +1,33 @@
+; RUN: opt < %s -simplify-libcalls -S | FileCheck %s
+; rdar://7235530
+
+; SimplifyLibcalls should optimize pow(x, 0.5) to sqrt plus code to handle
+; special cases. The readonly attribute on the call should be preserved.
+
+; CHECK: define float @foo(float %x) nounwind {
+; CHECK:   %sqrtf = call float @sqrtf(float %x) readonly
+; CHECK:   %fabsf = call float @fabsf(float %sqrtf) readonly
+; CHECK:   %tmp = fcmp oeq float %x, 0xFFF0000000000000
+; CHECK:   %tmp1 = select i1 %tmp, float 0x7FF0000000000000, float %fabsf
+; CHECK:   ret float %tmp1
+
+define float @foo(float %x) nounwind {
+  %retval = call float @powf(float %x, float 0.5) readonly
+  ret float %retval
+}
+
+; CHECK: define double @doo(double %x) nounwind {
+; CHECK:   %sqrt = call double @sqrt(double %x) readonly
+; CHECK:   %fabs = call double @fabs(double %sqrt) readonly
+; CHECK:   %tmp = fcmp oeq double %x, 0xFFF0000000000000
+; CHECK:   %tmp1 = select i1 %tmp, double 0x7FF0000000000000, double %fabs
+; CHECK:   ret double %tmp1
+; CHECK: }
+
+define double @doo(double %x) nounwind {
+  %retval = call double @pow(double %x, double 0.5) readonly
+  ret double %retval
+}
+
+declare float @powf(float, float) nounwind readonly
+declare double @pow(double, double) nounwind readonly