Added a slew of SimplifyInstruction floating-point optimizations, many of which take advantage of fast-math flags. Test cases included.

  fsub X, +0 ==> X
  fsub X, -0 ==> X, when we know X is not -0
  fsub +/-0.0, (fsub -0.0, X) ==> X
  fsub nsz +/-0.0, (fsub +/-0.0, X) ==> X
  fsub nnan ninf X, X ==> 0.0
  fadd nsz X, 0 ==> X
  fadd [nnan ninf] X, (fsub [nnan ninf] 0, X) ==> 0
    where nnan and ninf have to occur at least once somewhere in this expression
  fmul X, 1.0 ==> X

llvm-svn: 169940

1 files changed, 35 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll b/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll
new file mode 100644
index 00000000000..f9c364cade3
--- /dev/null
+++ b/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll
@@ -0,0 +1,35 @@
+; RUN: opt < %s -instsimplify -S | FileCheck %s
+
+; fsub 0, (fsub 0, X) ==> X
+; CHECK: @fsub_0_0_x
+define float @fsub_0_0_x(float %a) {
+  %t1 = fsub float -0.0, %a
+  %ret = fsub float -0.0, %t1
+
+; CHECK: ret float %a
+  ret float %ret
+}
+
+; fsub X, 0 ==> X
+; CHECK: @fsub_x_0
+define float @fsub_x_0(float %a) {
+  %ret = fsub float %a, 0.0
+; CHECK ret float %a
+  ret float %ret
+}
+
+; fadd X, -0 ==> X
+; CHECK: @fadd_x_n0
+define float @fadd_x_n0(float %a) {
+  %ret = fadd float %a, -0.0
+; CHECK ret float %a
+  ret float %ret
+}
+
+; fmul X, 1.0 ==> X
+; CHECK: @fmul_X_1
+define double @fmul_X_1(double %a) {
+  %b = fmul double 1.000000e+00, %a                ; <double> [#uses=1]
+  ; CHECK: ret double %a
+  ret double %b
+}