Don't generate sbfx / ubfx with negative lsb field. Patch by David Conrad.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84813 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/ARMISelDAGToDAG.cpp b/lib/Target/ARM/ARMISelDAGToDAG.cpp
index 6e976936d9880db40ad0229be91909164ffcbcb9..5c1835b46a224a2eacea9d9e448e3df13890d2c1 100644 (file)
--- a/lib/Target/ARM/ARMISelDAGToDAG.cpp
+++ b/lib/Target/ARM/ARMISelDAGToDAG.cpp
@@ -1287,7 +1287,7 @@ SDNode *ARMDAGToDAGISel::SelectV6T2BitfieldExtractOp(SDValue Op,
       assert(Srl_imm > 0 && Srl_imm < 32 && "bad amount in shift node!");
       unsigned Width = 32 - Srl_imm;
       int LSB = Srl_imm - Shl_imm;
-      if ((LSB + Width) > 32)
+      if (LSB < 0)
         return NULL;
       SDValue Reg0 = CurDAG->getRegister(0, MVT::i32);
       SDValue Ops[] = { Op.getOperand(0).getOperand(0),

diff --git a/test/CodeGen/ARM/sbfx.ll b/test/CodeGen/ARM/sbfx.ll
index 923f52a86862644e5e784244e01bf28c9d2d2766..6f1d87d2c17bd8e5d38c73a72d5add307aa8c949 100644 (file)
--- a/test/CodeGen/ARM/sbfx.ll
+++ b/test/CodeGen/ARM/sbfx.ll
@@ -35,3 +35,13 @@ entry:
     %tmp2 = lshr i32 %tmp, 29
     ret i32 %tmp2
 }
+
+define i32 @f5(i32 %a) {
+entry:
+; CHECK: f5:
+; CHECK-NOT: sbfx
+; CHECK: bx
+    %tmp = shl i32 %a, 3
+    %tmp2 = ashr i32 %tmp, 1
+    ret i32 %tmp2
+}