Optimize square root squared (PR21126).

[oota-llvm.git] / test / Transforms / InstCombine / fmul.ll

diff --git a/test/Transforms/InstCombine/fmul.ll b/test/Transforms/InstCombine/fmul.ll
index 18cbf9da53615f12ecc0cc4b30e52e1064e583da..3c8bab9ffb53e467df60781e00b5c841d2ac586c 100644 (file)
--- a/test/Transforms/InstCombine/fmul.ll
+++ b/test/Transforms/InstCombine/fmul.ll
@@ -123,3 +123,32 @@ define float @test11(float %x, float %y) {
 ; CHECK-NOT: fadd float
 ; CHECK: fadd fast float
 }
+
+; PR21126: http://llvm.org/bugs/show_bug.cgi?id=21126
+; With unsafe/fast math, sqrt(X) * sqrt(X) is just X.
+declare double @llvm.sqrt.f64(double)
+
+define double @sqrt_squared1(double %f) #0 {
+  %sqrt = call double @llvm.sqrt.f64(double %f)
+  %mul = fmul fast double %sqrt, %sqrt
+  ret double %mul
+; CHECK-LABEL: @sqrt_squared1(
+; CHECK-NEXT: ret double %f
+}
+
+; With unsafe/fast math, sqrt(X) * sqrt(X) is just X, 
+; but make sure another use of the sqrt is intact.
+; Note that the remaining fmul is altered but is not 'fast'
+; itself because it was not marked 'fast' originally. 
+; Thus, we have an overall fast result, but no more indication of
+; 'fast'ness in the code.
+define double @sqrt_squared2(double %f) #0 {
+  %sqrt = call double @llvm.sqrt.f64(double %f)
+  %mul1 = fmul fast double %sqrt, %sqrt
+  %mul2 = fmul double %mul1, %sqrt
+  ret double %mul2
+; CHECK-LABEL: @sqrt_squared2(
+; CHECK-NEXT: %sqrt = call double @llvm.sqrt.f64(double %f)
+; CHECK-NEXT: %mul2 = fmul double %sqrt, %f
+; CHECK-NEXT: ret double %mul2
+}