ARM: add patterns for [su]xta[bh] from just a shift.

Although the final shifter operand is a rotate, this actually only matters for
the half-word extends when the amount == 24. Otherwise folding a shift in is
just as good.

llvm-svn: 213753

2 files changed, 20 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/ARMInstrInfo.td b/llvm/lib/Target/ARM/ARMInstrInfo.td
index 70c779dec20..b2d6a68b960 100644
--- a/llvm/lib/Target/ARM/ARMInstrInfo.td
+++ b/llvm/lib/Target/ARM/ARMInstrInfo.td
@@ -633,6 +633,8 @@ def imm32 : Operand<i32>, ImmLeaf<i32, [{ return Imm == 32; }]> {
   let ParserMatchClass = Imm32AsmOperand;
 }
 
+def imm8_or_16 : ImmLeaf<i32, [{ return Imm == 8 || Imm == 16;}]>;
+
 /// imm1_7 predicate - Immediate in the range [1,7].
 def Imm1_7AsmOperand: ImmAsmOperand { let Name = "Imm1_7"; }
 def imm1_7 : Operand<i32>, ImmLeaf<i32, [{ return Imm > 0 && Imm < 8; }]> {
diff --git a/llvm/lib/Target/ARM/ARMInstrThumb2.td b/llvm/lib/Target/ARM/ARMInstrThumb2.td
index 85e93516807..8e2324ce06c 100644
--- a/llvm/lib/Target/ARM/ARMInstrThumb2.td
+++ b/llvm/lib/Target/ARM/ARMInstrThumb2.td
@@ -1973,6 +1973,16 @@ def t2SXTAH : T2I_exta_rrot<0b000, "sxtah",
                         BinOpFrag<(add node:$LHS, (sext_inreg node:$RHS,i16))>>;
 def t2SXTAB16 : T2I_exta_rrot_np<0b010, "sxtab16">;
 
+// A simple right-shift can also be used in most cases (the exception is the
+// SXTH operations with a rotate of 24: there the non-contiguous bits are
+// relevant).
+def : Pat<(add rGPR:$Rn, (sext_inreg (srl rGPR:$Rm, rot_imm:$rot), i8)),
+          (t2SXTAB rGPR:$Rn, rGPR:$Rm, rot_imm:$rot)>,
+      Requires<[HasT2ExtractPack, IsThumb2]>;
+def : Pat<(add rGPR:$Rn, (sext_inreg (srl rGPR:$Rm, imm8_or_16:$rot), i16)),
+          (t2SXTAH rGPR:$Rn, rGPR:$Rm, rot_imm:$rot)>,
+      Requires<[HasT2ExtractPack, IsThumb2]>;
+
 // Zero extenders
 
 let AddedComplexity = 16 in {
@@ -1999,8 +2009,16 @@ def t2UXTAB : T2I_exta_rrot<0b101, "uxtab",
 def t2UXTAH : T2I_exta_rrot<0b001, "uxtah",
                            BinOpFrag<(add node:$LHS, (and node:$RHS, 0xFFFF))>>;
 def t2UXTAB16 : T2I_exta_rrot_np<0b011, "uxtab16">;
+
+def : Pat<(add rGPR:$Rn, (and (srl rGPR:$Rm, rot_imm:$rot), 0xFF)),
+          (t2UXTAB rGPR:$Rn, rGPR:$Rm, rot_imm:$rot)>,
+      Requires<[HasT2ExtractPack, IsThumb2]>;
+def : Pat<(add rGPR:$Rn, (and (srl rGPR:$Rm, imm8_or_16:$rot), 0xFFFF)),
+          (t2UXTAH rGPR:$Rn, rGPR:$Rm, rot_imm:$rot)>,
+      Requires<[HasT2ExtractPack, IsThumb2]>;
 }
 
+
 //===----------------------------------------------------------------------===//
 //  Arithmetic Instructions.
 //