[InstCombine] add tests for sqrt+fdiv+fmul; NFC

Examples based on recent llvm-dev thread. These are specific
patterns of more general enhancements that would solve these.

llvm-svn: 357780

diff --git a/llvm/test/Transforms/InstCombine/fmul-sqrt.ll b/llvm/test/Transforms/InstCombine/fmul-sqrt.ll
index 61d98c7..8161e31 100644 (file)
--- a/llvm/test/Transforms/InstCombine/fmul-sqrt.ll
+++ b/llvm/test/Transforms/InstCombine/fmul-sqrt.ll
@@ -2,6 +2,7 @@
 ; RUN: opt -S -instcombine < %s | FileCheck %s
 
 declare double @llvm.sqrt.f64(double) nounwind readnone speculatable
+declare <2 x float> @llvm.sqrt.v2f32(<2 x float>)
 declare void @use(double)
 
 ; sqrt(a) * sqrt(b) no math flags
@@ -87,3 +88,45 @@ define double @sqrt_a_sqrt_b_sqrt_c_sqrt_d_reassoc(double %a, double %b, double
   ret double %mul2
 }
 
+define double @sqrt_squared(double %x) {
+; CHECK-LABEL: @sqrt_squared(
+; CHECK-NEXT:    [[SQRT:%.*]] = call fast double @llvm.sqrt.f64(double [[X:%.*]])
+; CHECK-NEXT:    [[RSQRT:%.*]] = fdiv fast double 1.000000e+00, [[SQRT]]
+; CHECK-NEXT:    [[SQUARED:%.*]] = fmul fast double [[RSQRT]], [[RSQRT]]
+; CHECK-NEXT:    ret double [[SQUARED]]
+;
+  %sqrt = call fast double @llvm.sqrt.f64(double %x)
+  %rsqrt = fdiv fast double 1.0, %sqrt
+  %squared = fmul fast double %rsqrt, %rsqrt
+  ret double %squared
+}
+
+define double @sqrt_squared_extra_use(double %x) {
+; CHECK-LABEL: @sqrt_squared_extra_use(
+; CHECK-NEXT:    [[SQRT:%.*]] = call fast double @llvm.sqrt.f64(double [[X:%.*]])
+; CHECK-NEXT:    [[RSQRT:%.*]] = fdiv fast double 1.000000e+00, [[SQRT]]
+; CHECK-NEXT:    call void @use(double [[RSQRT]])
+; CHECK-NEXT:    [[SQUARED:%.*]] = fmul fast double [[RSQRT]], [[RSQRT]]
+; CHECK-NEXT:    ret double [[SQUARED]]
+;
+  %sqrt = call fast double @llvm.sqrt.f64(double %x)
+  %rsqrt = fdiv fast double 1.0, %sqrt
+  call void @use(double %rsqrt)
+  %squared = fmul fast double %rsqrt, %rsqrt
+  ret double %squared
+}
+
+; Minimal FMF to reassociate fmul+fdiv.
+
+define <2 x float> @sqrt_squared_vec(<2 x float> %x) {
+; CHECK-LABEL: @sqrt_squared_vec(
+; CHECK-NEXT:    [[SQRT:%.*]] = call <2 x float> @llvm.sqrt.v2f32(<2 x float> [[X:%.*]])
+; CHECK-NEXT:    [[RSQRT:%.*]] = fdiv <2 x float> <float 1.000000e+00, float 1.000000e+00>, [[SQRT]]
+; CHECK-NEXT:    [[SQUARED:%.*]] = fmul reassoc <2 x float> [[RSQRT]], [[RSQRT]]
+; CHECK-NEXT:    ret <2 x float> [[SQUARED]]
+;
+  %sqrt = call <2 x float> @llvm.sqrt.v2f32(<2 x float> %x)
+  %rsqrt = fdiv <2 x float> <float 1.0, float 1.0>, %sqrt
+  %squared = fmul reassoc <2 x float> %rsqrt, %rsqrt
+  ret <2 x float> %squared
+}