Fix a mistake in the computation of leading zeros for udiv.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50591 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 39 insertions, 0 deletions

diff --git a/test/Transforms/InstCombine/udiv-simplify-bug-0.ll b/test/Transforms/InstCombine/udiv-simplify-bug-0.ll
new file mode 100644
index 0000000000..5bcaa66366
--- /dev/null
+++ b/test/Transforms/InstCombine/udiv-simplify-bug-0.ll
@@ -0,0 +1,14 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {ret i64 0} | count 2
+
+define i64 @foo(i32 %x) nounwind {
+  %y = lshr i32 %x, 1
+  %r = udiv i32 %y, -1
+  %z = sext i32 %r to i64
+  ret i64 %z
+}
+define i64 @bar(i32 %x) nounwind {
+  %y = lshr i32 %x, 31
+  %r = udiv i32 %y, 3
+  %z = sext i32 %r to i64
+  ret i64 %z
+}
diff --git a/test/Transforms/InstCombine/udiv-simplify-bug-1.ll b/test/Transforms/InstCombine/udiv-simplify-bug-1.ll
new file mode 100644
index 0000000000..6e76bcfd75
--- /dev/null
+++ b/test/Transforms/InstCombine/udiv-simplify-bug-1.ll
@@ -0,0 +1,25 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis > %t1.ll
+; RUN: grep udiv %t1.ll | count 3
+; RUN: grep zext %t1.ll | count 3
+; PR2274
+
+; The udiv instructions shouldn't be optimized away, and the
+; sext instructions should be optimized to zext.
+
+define i64 @foo(i32 %x) nounwind {
+  %r = udiv i32 %x, -1
+  %z = sext i32 %r to i64
+  ret i64 %z
+}
+define i64 @bar(i32 %x) nounwind {
+  %y = lshr i32 %x, 30
+  %r = udiv i32 %y, 3
+  %z = sext i32 %r to i64
+  ret i64 %z
+}
+define i64 @qux(i32 %x, i32 %v) nounwind {
+  %y = lshr i32 %x, 31
+  %r = udiv i32 %y, %v
+  %z = sext i32 %r to i64
+  ret i64 %z
+}