[X86] Prevent an assertion failure if a gather intrinsic is passed a non-constant...

This isn't legal code, but we shouldn't crash on it. Now we just don't convert the gather intrinsic if the scale isn't constant and let it go through to isel where we'll report an isel failure.

Fixes PR33772.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308267 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index a48bfd57af76b233d7cc5371e7600cdd6417ef17..9ecca53bbf45a8ce5801aadfc9a5ea033375dfb2 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -20195,7 +20195,10 @@ static SDValue getAVX2GatherNode(unsigned Opc, SDValue Op, SelectionDAG &DAG,
                                  SDValue Index, SDValue ScaleOp, SDValue Chain,
                                  const X86Subtarget &Subtarget) {
   SDLoc dl(Op);
-  auto *C = cast<ConstantSDNode>(ScaleOp);
+  auto *C = dyn_cast<ConstantSDNode>(ScaleOp);
+  // Scale must be constant.
+  if (!C)
+    return SDValue();
   SDValue Scale = DAG.getTargetConstant(C->getZExtValue(), dl, MVT::i8);
   EVT MaskVT = Mask.getValueType();
   SDVTList VTs = DAG.getVTList(Op.getValueType(), MaskVT, MVT::Other);
@@ -20217,7 +20220,10 @@ static SDValue getGatherNode(unsigned Opc, SDValue Op, SelectionDAG &DAG,
                               SDValue Index, SDValue ScaleOp, SDValue Chain,
                               const X86Subtarget &Subtarget) {
   SDLoc dl(Op);
-  auto *C = cast<ConstantSDNode>(ScaleOp);
+  auto *C = dyn_cast<ConstantSDNode>(ScaleOp);
+  // Scale must be constant.
+  if (!C)
+    return SDValue();
   SDValue Scale = DAG.getTargetConstant(C->getZExtValue(), dl, MVT::i8);
   MVT MaskVT = MVT::getVectorVT(MVT::i1,
                              Index.getSimpleValueType().getVectorNumElements());
@@ -20242,7 +20248,10 @@ static SDValue getScatterNode(unsigned Opc, SDValue Op, SelectionDAG &DAG,
                                SDValue Index, SDValue ScaleOp, SDValue Chain,
                                const X86Subtarget &Subtarget) {
   SDLoc dl(Op);
-  auto *C = cast<ConstantSDNode>(ScaleOp);
+  auto *C = dyn_cast<ConstantSDNode>(ScaleOp);
+  // Scale must be constant.
+  if (!C)
+    return SDValue();
   SDValue Scale = DAG.getTargetConstant(C->getZExtValue(), dl, MVT::i8);
   SDValue Disp = DAG.getTargetConstant(0, dl, MVT::i32);
   SDValue Segment = DAG.getRegister(0, MVT::i32);
@@ -20261,7 +20270,10 @@ static SDValue getPrefetchNode(unsigned Opc, SDValue Op, SelectionDAG &DAG,
                                SDValue ScaleOp, SDValue Chain,
                                const X86Subtarget &Subtarget) {
   SDLoc dl(Op);
-  auto *C = cast<ConstantSDNode>(ScaleOp);
+  auto *C = dyn_cast<ConstantSDNode>(ScaleOp);
+  // Scale must be constant.
+  if (!C)
+    return SDValue();
   SDValue Scale = DAG.getTargetConstant(C->getZExtValue(), dl, MVT::i8);
   SDValue Disp = DAG.getTargetConstant(0, dl, MVT::i32);
   SDValue Segment = DAG.getRegister(0, MVT::i32);

diff --git a/test/CodeGen/X86/pr33772.ll b/test/CodeGen/X86/pr33772.ll
new file mode 100644 (file)
index 0000000..2a9b990
--- /dev/null
+++ b/test/CodeGen/X86/pr33772.ll
@@ -0,0 +1,13 @@
+; RUN: not llc < %s -mcpu=skylake-avx512 2>&1 | FileCheck %s
+
+; make sure we don't crash if scale for gather isn't constant.
+
+; CHECK: LLVM ERROR: Cannot select: intrinsic %llvm.x86.avx512.gather.dpi.512
+declare <16 x i32> @llvm.x86.avx512.gather.dpi.512(<16 x i32>, i8*, <16 x i32>, i16, i32)
+
+define internal <16 x i32> @__gather_base_offsets32_i32(i8* readonly %ptr, i32 %offset_scale, <16 x i32> %offsets, <16 x i8> %vecmask) {
+  %mask_vec_i1.i.i = icmp ne <16 x i8> %vecmask, zeroinitializer
+  %mask_i16.i = bitcast <16 x i1> %mask_vec_i1.i.i to i16
+  %res = tail call <16 x i32> @llvm.x86.avx512.gather.dpi.512(<16 x i32> undef, i8* %ptr, <16 x i32> %offsets, i16 %mask_i16.i, i32 %offset_scale)
+  ret <16 x i32> %res
+}