[llvm] r336258 - [NFC] Add test that shows that InstCombine can do better

[Max Kazantsev via llvm-commits]

Author: mkazantsev
Date: Wed Jul  4 03:32:02 2018
New Revision: 336258

URL: http://llvm.org/viewvc/llvm-project?rev=336258&view=rev
Log:
[NFC] Add test that shows that InstCombine can do better

Added:
    llvm/trunk/test/Transforms/InstCombine/max_known_bits.ll

Added: llvm/trunk/test/Transforms/InstCombine/max_known_bits.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/max_known_bits.ll?rev=336258&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/max_known_bits.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/max_known_bits.ll Wed Jul  4 03:32:02 2018
@@ -0,0 +1,24 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -instcombine < %s | FileCheck %s
+; TODO: The entire thing should be folded to and i16 %0, 255.
+
+define i16 @foo(i16 )  {
+; CHECK-LABEL: @foo(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP1:%.*]] = and i16 [[TMP0:%.*]], 255
+; CHECK-NEXT:    [[TMP2:%.*]] = zext i16 [[TMP1]] to i32
+; CHECK-NEXT:    [[TMP3:%.*]] = icmp ult i32 [[TMP2]], 255
+; CHECK-NEXT:    [[TMP4:%.*]] = select i1 [[TMP3]], i32 [[TMP2]], i32 255
+; CHECK-NEXT:    [[TMP5:%.*]] = trunc i32 [[TMP4]] to i16
+; CHECK-NEXT:    [[TMP6:%.*]] = and i16 [[TMP5]], 255
+; CHECK-NEXT:    ret i16 [[TMP6]]
+;
+entry:
+  %1 = and i16 %0, 255
+  %2 = zext i16 %1 to i32
+  %3 = icmp ult i32 %2, 255
+  %4 = select i1 %3, i32 %2, i32 255
+  %5 = trunc i32 %4 to i16
+  %6 = and i16 %5, 255
+  ret i16 %6
+}