Don't do (X != Y) ? X : Y -> X for floating-point values; it doesn't

handle NaN properly.

Do (X une Y) ? X : Y  -> X if one of X and Y is not zero.

llvm-svn: 96955

1 files changed, 53 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/fcmp-select.ll b/llvm/test/Transforms/InstCombine/fcmp-select.ll
new file mode 100644
index 00000000000..e04ab3e8923
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/fcmp-select.ll
@@ -0,0 +1,53 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; x != y ? x : y -> x if it's the right kind of != and at least
+; one of x and y is not negative zero.
+
+; CHECK: f0
+; CHECK: ret double %x
+define double @f0(double %x) nounwind readnone {
+entry:
+  %cmp = fcmp une double %x, -1.0
+  %cond = select i1 %cmp, double %x, double -1.0
+  ret double %cond
+}
+; CHECK: f1
+; CHECK: ret double -1.000000e+00
+define double @f1(double %x) nounwind readnone {
+entry:
+  %cmp = fcmp une double %x, -1.0
+  %cond = select i1 %cmp, double -1.0, double %x
+  ret double %cond
+}
+; CHECK: f2
+; CHECK: ret double %cond
+define double @f2(double %x, double %y) nounwind readnone {
+entry:
+  %cmp = fcmp une double %x, %y
+  %cond = select i1 %cmp, double %x, double %y
+  ret double %cond
+}
+; CHECK: f3
+; CHECK: ret double %cond
+define double @f3(double %x, double %y) nounwind readnone {
+entry:
+  %cmp = fcmp une double %x, %y
+  %cond = select i1 %cmp, double %y, double %x
+  ret double %cond
+}
+; CHECK: f4
+; CHECK: ret double %cond
+define double @f4(double %x) nounwind readnone {
+entry:
+  %cmp = fcmp one double %x, -1.0
+  %cond = select i1 %cmp, double %x, double -1.0
+  ret double %cond
+}
+; CHECK: f5
+; CHECK: ret double %cond
+define double @f5(double %x) nounwind readnone {
+entry:
+  %cmp = fcmp one double %x, -1.0
+  %cond = select i1 %cmp, double -1.0, double %x
+  ret double %cond
+}