SelectionDAG: Don't constant fold target-specific nodes.

FoldConstantArithmetic() only knows how to deal with a few target independent
ISD opcodes. Bail early if it sees a target-specific ISD node. These node do
funny things with operand types which may break the assumptions of the code
that follows, and there's no actual folding that can be done anyway. For example,
non-constant 256 bit vector shifts on X86 have a shift-amount operand that's a
128-bit v4i32 vector regardless of what the first operand type is and that breaks
the assumption that the operand types must match.

rdar://16530923

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205937 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 8f624508398b0a1838cd847a6670b32a51a01761..e85739688cff47c9b8ecba9fbf7a7747c27b5d69 100644 (file)
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2811,6 +2811,12 @@ SDValue SelectionDAG::getNode(unsigned Opcode, SDLoc DL,
 
 SDValue SelectionDAG::FoldConstantArithmetic(unsigned Opcode, EVT VT,
                                              SDNode *Cst1, SDNode *Cst2) {
+  // If the opcode is a target-specific ISD node, there's nothing we can
+  // do here and the operand rules may not line up with the below, so
+  // bail early.
+  if (Opcode >= ISD::BUILTIN_OP_END)
+    return SDValue();
+
   SmallVector<std::pair<ConstantSDNode *, ConstantSDNode *>, 4> Inputs;
   SmallVector<SDValue, 4> Outputs;
   EVT SVT = VT.getScalarType();

diff --git a/test/CodeGen/X86/avx2-vector-shifts.ll b/test/CodeGen/X86/avx2-vector-shifts.ll
index 4ae2905ef2248dd1acc955fbb9f6774ad86d9f2c..e355301dd051a4abbd4561e1b6570b0d8fb7413c 100644 (file)
--- a/test/CodeGen/X86/avx2-vector-shifts.ll
+++ b/test/CodeGen/X86/avx2-vector-shifts.ll
@@ -52,6 +52,16 @@ entry:
 ; CHECK: vpaddd  %ymm0, %ymm0, %ymm0
 ; CHECK: ret
 
+define <8 x i32> @test_vpslld_var(i32 %shift) {
+  %amt = insertelement <8 x i32> undef, i32 %shift, i32 0
+  %tmp = shl <8 x i32> <i32 192, i32 193, i32 194, i32 195, i32 196, i32 197, i32 198, i32 199>, %amt
+  ret <8 x i32> %tmp
+}
+
+; CHECK-LABEL: test_vpslld_var:
+; CHECK: vpslld %xmm0, %ymm1, %ymm0
+; CHECK: ret
+
 define <8 x i32> @test_slld_3(<8 x i32> %InVec) {
 entry:
   %shl = shl <8 x i32> %InVec, <i32 31, i32 31, i32 31, i32 31, i32 31, i32 31, i32 31, i32 31>