[RISCV] Implement isLegalAddImmediate

This causes a trivial improvement in the recently added lsr-legaladdimm.ll 
test case.

llvm-svn: 330937

2 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index b00f6605bdc..7c1d01845b4 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -183,6 +183,10 @@ bool RISCVTargetLowering::isLegalAddressingMode(const DataLayout &DL,
   return true;
 }
 
+bool RISCVTargetLowering::isLegalAddImmediate(int64_t Imm) const {
+  return isInt<12>(Imm);
+}
+
 // Changes the condition code and swaps operands if necessary, so the SetCC
 // operation matches one of the comparisons supported directly in the RISC-V
 // ISA.
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.h b/llvm/lib/Target/RISCV/RISCVISelLowering.h
index c411784e9d8..7e4a1347127 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.h
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.h
@@ -42,6 +42,7 @@ public:
   bool isLegalAddressingMode(const DataLayout &DL, const AddrMode &AM, Type *Ty,
                              unsigned AS,
                              Instruction *I = nullptr) const override;
+  bool isLegalAddImmediate(int64_t Imm) const override;
 
   // Provide custom lowering hooks for some operations.
   SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const override;