1 files changed, 51 insertions, 0 deletions
diff --git a/llvm/test/Transforms/InstCombine/zext-or-icmp.ll b/llvm/test/Transforms/InstCombine/zext-or-icmp.ll
new file mode 100644
index 00000000000..afbe36da3e3
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/zext-or-icmp.ll
@@ -0,0 +1,51 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; Remove an icmp by using its operand in the subsequent logic directly.
+
+define i8 @zext_or_icmp_icmp(i8 %a, i8 %b) {
+  %mask = and i8 %a, 1
+  %toBool1 = icmp eq i8 %mask, 0
+  %toBool2 = icmp eq i8 %b, 0
+  %bothCond = or i1 %toBool1, %toBool2
+  %zext = zext i1 %bothCond to i8
+  ret i8 %zext
+
+; CHECK-LABEL: zext_or_icmp_icmp(
+; CHECK-NEXT:    %mask = and i8 %a, 1
+; CHECK-NEXT:    %toBool2 = icmp eq i8 %b, 0
+; CHECK-NEXT:    %toBool22 = zext i1 %toBool2 to i8
+; CHECK-NEXT:    %1 = xor i8 %mask, 1
+; CHECK-NEXT:    %zext = or i8 %1, %toBool22
+; CHECK-NEXT:    ret i8 %zext
+}
+
+; Here, widening the or from i1 to i32 and removing one of the icmps would
+; widen an undef value (created by the out-of-range shift), increasing the
+; range of valid values for the return, so we can't do it.
+define i32 @dont_widen_undef() {
+entry:
+  br label %block2
+
+block1:
+  br label %block2
+
+block2:
+  %m.011 = phi i32 [ 33, %entry ], [ 0, %block1 ]
+  %cmp.i = icmp ugt i32 %m.011, 1
+  %m.1.op = lshr i32 1, %m.011
+  %sext.mask = and i32 %m.1.op, 65535
+  %cmp115 = icmp ne i32 %sext.mask, 0
+  %cmp1 = or i1 %cmp.i, %cmp115
+  %conv2 = zext i1 %cmp1 to i32
+  ret i32 %conv2
+
+; CHECK-LABEL: dont_widen_undef(
+; CHECK:         %m.011 = phi i32 [ 33, %entry ], [ 0, %block1 ]
+; CHECK-NEXT:    %cmp.i = icmp ugt i32 %m.011, 1
+; CHECK-NEXT:    %m.1.op = lshr i32 1, %m.011
+; CHECK-NEXT:    %sext.mask = and i32 %m.1.op, 65535
+; CHECK-NEXT:    %cmp115 = icmp ne i32 %sext.mask, 0
+; CHECK-NEXT:    %cmp1 = or i1 %cmp.i, %cmp115
+; CHECK-NEXT:    %conv2 = zext i1 %cmp1 to i32
+; CHECK-NEXT:    ret i32 %conv2
+}