InstCombine: Shrink "fcmp (fpext x), C" to "fcmp x, C" if C can be losslessly converted to the type of x.

Fixes PR9592.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128625 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 23 insertions, 0 deletions

diff --git a/test/Transforms/InstCombine/fcmp.ll b/test/Transforms/InstCombine/fcmp.ll
index bef4855a0e..49bd50717d 100644
--- a/test/Transforms/InstCombine/fcmp.ll
+++ b/test/Transforms/InstCombine/fcmp.ll
@@ -9,3 +9,26 @@ define i1 @test1(float %x, float %y) nounwind {
 ; CHECK-NEXT: fcmp ogt float %x, %y
 }
 
+define i1 @test2(float %a) nounwind {
+  %ext = fpext float %a to double
+  %cmp = fcmp ogt double %ext, 1.000000e+00
+  ret i1 %cmp
+; CHECK: @test2
+; CHECK-NEXT: fcmp ogt float %a, 1.0
+}
+
+define i1 @test3(float %a) nounwind {
+  %ext = fpext float %a to double
+  %cmp = fcmp ogt double %ext, 0x3FF0000000000001 ; more precision than float.
+  ret i1 %cmp
+; CHECK: @test3
+; CHECK-NEXT: fpext float %a to double
+}
+
+define i1 @test4(float %a) nounwind {
+  %ext = fpext float %a to double
+  %cmp = fcmp ogt double %ext, 0x36A0000000000000 ; denormal in float.
+  ret i1 %cmp
+; CHECK: @test4
+; CHECK-NEXT: fpext float %a to double
+}