[AArch64] Fix assertion failure caused by an invalid comparison between APInt values.

APInt only knows how to compare values with the same BitWidth and asserts
in all other cases.

With this fix, function PerformORCombine does not use the APInt equality
operator if the APInt values returned by 'isConstantSplat' differ in BitWidth.
In that case they are different and no comparison is needed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199119 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/AArch64/AArch64ISelLowering.cpp b/lib/Target/AArch64/AArch64ISelLowering.cpp
index ce9ce3aeb5f8a21a6a045e45e9d885b2209da7c3..317a41a05f4d495b921815f929872d5f8f92e21f 100644 (file)
--- a/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -3476,8 +3476,9 @@ static SDValue PerformORCombine(SDNode *N,
       BuildVectorSDNode *BVN1 = dyn_cast<BuildVectorSDNode>(N1->getOperand(1));
       APInt SplatBits1;
       if (BVN1 && BVN1->isConstantSplat(SplatBits1, SplatUndef, SplatBitSize,
-                                        HasAnyUndefs) &&
-          !HasAnyUndefs && SplatBits0 == ~SplatBits1) {
+                                        HasAnyUndefs) && !HasAnyUndefs &&
+          SplatBits0.getBitWidth() == SplatBits1.getBitWidth() &&
+          SplatBits0 == ~SplatBits1) {
 
         return DAG.getNode(ISD::VSELECT, DL, VT, N0->getOperand(1),
                            N0->getOperand(0), N1->getOperand(0));

diff --git a/test/CodeGen/AArch64/neon-or-combine.ll b/test/CodeGen/AArch64/neon-or-combine.ll
new file mode 100644 (file)
index 0000000..260f693
--- /dev/null
+++ b/test/CodeGen/AArch64/neon-or-combine.ll
@@ -0,0 +1,29 @@
+; RUN: llc < %s -mtriple=aarch64-none-linux-gnu -mattr=+neon | FileCheck %s
+
+; Check that the DAGCombiner does not crash with an assertion failure
+; when performing a target specific combine to simplify a 'or' dag node
+; according to the following rule:
+;   (or (and B, A), (and C, ~A)) => (VBSL A, B, C)
+; The assertion failure was caused by an invalid comparison between APInt
+; values with different 'BitWidth'.
+
+define <8 x i8> @test1(<8 x i8> %a, <8 x i8> %b)  {
+  %tmp1 = and <8 x i8> %a, < i8 -1, i8 -1, i8 0, i8 0, i8 -1, i8 -1, i8 0, i8 0 >
+  %tmp2 = and <8 x i8> %b, < i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0 >
+  %tmp3 = or <8 x i8> %tmp1, %tmp2
+  ret <8 x i8> %tmp3
+}
+
+; CHECK-LABEL: test1
+; CHECK: ret
+
+define <16 x i8> @test2(<16 x i8> %a, <16 x i8> %b) {
+  %tmp1 = and <16 x i8> %a, < i8 -1, i8 -1, i8 -1, i8 -1, i8 -1, i8 -1, i8 -1, i8 -1, i8 -1, i8 -1, i8 -1, i8 -1, i8 -1, i8 -1, i8 -1, i8 -1 >
+  %tmp2 = and <16 x i8> %b, < i8 -1, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0 >
+  %tmp3 = or <16 x i8> %tmp1, %tmp2
+  ret <16 x i8> %tmp3
+}
+
+; CHECK-LABEL: test2
+; CHECK: ret
+