From: Pawel Bylica <chfast@gmail.com>
Date: Mon, 22 Jun 2015 15:58:11 +0000 (+0000)
Subject: Fix shl folding in DAG combiner.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=39befc6ca87809f13cf33bb6aec5ddc36c560d92;p=oota-llvm.git

Fix shl folding in DAG combiner.

Summary: The code responsible for shl folding in the DAGCombiner was assuming incorrectly that all constants are less than 64 bits. This patch simply changes the way values are compared.

Test Plan: A regression test included.

Reviewers: andreadb

Reviewed By: andreadb

Subscribers: andreadb, test, llvm-commits

Differential Revision: http://reviews.llvm.org/D10602

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240291 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index bc2e5f13d43..80a1b5b3be7 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -4275,7 +4275,7 @@ SDValue DAGCombiner::visitSHL(SDNode *N) {
   if (isNullConstant(N0))
     return N0;
   // fold (shl x, c >= size(x)) -> undef
-  if (N1C && N1C->getZExtValue() >= OpSizeInBits)
+  if (N1C && N1C->getAPIntValue().uge(OpSizeInBits))
     return DAG.getUNDEF(VT);
   // fold (shl x, 0) -> x
   if (N1C && N1C->isNullValue())
diff --git a/test/CodeGen/X86/fold-vector-shl-crash.ll b/test/CodeGen/X86/fold-vector-shl-crash.ll
new file mode 100644
index 00000000000..b0341e0739c
--- /dev/null
+++ b/test/CodeGen/X86/fold-vector-shl-crash.ll
@@ -0,0 +1,8 @@
+; RUN: llc < %s | FileCheck %s
+
+;CHECK-LABEL: test
+define <2 x i256> @test() {
+  %S = shufflevector <2 x i256> zeroinitializer, <2 x i256> <i256 -1, i256 -1>, <2 x i32> <i32 0, i32 2>
+  %B = shl <2 x i256> %S, <i256 -1, i256 -1> ; DAG Combiner crashes here
+  ret <2 x i256> %B
+}