Index: llvm/trunk/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
===================================================================
--- llvm/trunk/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
+++ llvm/trunk/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
@@ -260,6 +260,19 @@
            (VK == RISCVMCExpr::VK_RISCV_None || VK == RISCVMCExpr::VK_RISCV_LO);
   }
 
+  bool isSImm6NonZero() const {
+    RISCVMCExpr::VariantKind VK;
+    int64_t Imm;
+    bool IsValid;
+    bool IsConstantImm = evaluateConstantImm(Imm, VK);
+    if (!IsConstantImm)
+      IsValid = RISCVAsmParser::classifySymbolRef(getImm(), VK, Imm);
+    else
+      IsValid = ((Imm != 0) && isInt<6>(Imm));
+    return IsValid &&
+           (VK == RISCVMCExpr::VK_RISCV_None || VK == RISCVMCExpr::VK_RISCV_LO);
+  }
+
   bool isUImm6NonZero() const {
     int64_t Imm;
     RISCVMCExpr::VariantKind VK;
@@ -338,11 +351,11 @@
 
   bool isSImm13Lsb0() const { return isBareSimmNLsb0<13>(); }
 
-  bool isSImm10Lsb0000() const {
+  bool isSImm10Lsb0000NonZero() const {
     int64_t Imm;
     RISCVMCExpr::VariantKind VK;
     bool IsConstantImm = evaluateConstantImm(Imm, VK);
-    return IsConstantImm && isShiftedInt<6, 4>(Imm) &&
+    return IsConstantImm && (Imm != 0) && isShiftedInt<6, 4>(Imm) &&
            VK == RISCVMCExpr::VK_RISCV_None;
   }
 
@@ -613,6 +626,10 @@
   case Match_InvalidSImm6:
     return generateImmOutOfRangeError(Operands, ErrorInfo, -(1 << 5),
                                       (1 << 5) - 1);
+  case Match_InvalidSImm6NonZero:
+    return generateImmOutOfRangeError(Operands, ErrorInfo, -(1 << 5),
+                                      (1 << 5) - 1,
+        "immediate must be non-zero in the range");
   case Match_InvalidUImm6NonZero:
     return generateImmOutOfRangeError(Operands, ErrorInfo, 1, (1 << 6) - 1);
   case Match_InvalidUImm7Lsb00:
@@ -639,10 +656,10 @@
     return generateImmOutOfRangeError(
         Operands, ErrorInfo, 4, (1 << 10) - 4,
         "immediate must be a multiple of 4 bytes in the range");
-  case Match_InvalidSImm10Lsb0000:
+  case Match_InvalidSImm10Lsb0000NonZero:
     return generateImmOutOfRangeError(
         Operands, ErrorInfo, -(1 << 9), (1 << 9) - 16,
-        "immediate must be a multiple of 16 bytes in the range");
+        "immediate must be a multiple of 16 bytes and non-zero in the range");
   case Match_InvalidSImm12:
     return generateImmOutOfRangeError(Operands, ErrorInfo, -(1 << 11),
                                       (1 << 11) - 1);
Index: llvm/trunk/lib/Target/RISCV/RISCVInstrInfoC.td
===================================================================
--- llvm/trunk/lib/Target/RISCV/RISCVInstrInfoC.td
+++ llvm/trunk/lib/Target/RISCV/RISCVInstrInfoC.td
@@ -35,6 +35,13 @@
   let DecoderMethod = "decodeSImmOperand<6>";
 }
 
+def simm6nonzero : Operand<XLenVT>,
+                   ImmLeaf<XLenVT, [{return (Imm != 0) && isInt<6>(Imm);}]> {
+  let ParserMatchClass = SImmAsmOperand<6, "NonZero">;
+  let EncoderMethod = "getImmOpValue";
+  let DecoderMethod = "decodeSImmOperand<6>";
+}
+
 def uimm6nonzero : Operand<XLenVT>,
                    ImmLeaf<XLenVT, [{return isUInt<6>(Imm) && (Imm != 0);}]> {
   let ParserMatchClass = UImmAsmOperand<6, "NonZero">;
@@ -91,9 +98,10 @@
 }
 
 // A 10-bit signed immediate where the least significant four bits are zero.
-def simm10_lsb0000 : Operand<XLenVT>,
-                     ImmLeaf<XLenVT, [{return isShiftedInt<6, 4>(Imm);}]> {
-  let ParserMatchClass = SImmAsmOperand<10, "Lsb0000">;
+def simm10_lsb0000nonzero : Operand<XLenVT>,
+                            ImmLeaf<XLenVT,
+                            [{return (Imm != 0) && isShiftedInt<6, 4>(Imm);}]> {
+  let ParserMatchClass = SImmAsmOperand<10, "Lsb0000NonZero">;
   let EncoderMethod = "getImmOpValue";
   let DecoderMethod = "decodeSImmOperand<10>";
 }
@@ -253,7 +261,7 @@
 
 let hasSideEffects = 0, mayLoad = 0, mayStore = 0 in
 def C_ADDI : RVInst16CI<0b000, 0b01, (outs GPRNoX0:$rd_wb),
-                        (ins GPRNoX0:$rd, simm6:$imm),
+                        (ins GPRNoX0:$rd, simm6nonzero:$imm),
                         "c.addi", "$rd, $imm"> {
   let Constraints = "$rd = $rd_wb";
   let Inst{6-2} = imm{4-0};
@@ -282,7 +290,7 @@
 
 let hasSideEffects = 0, mayLoad = 0, mayStore = 0 in
 def C_ADDI16SP : RVInst16CI<0b011, 0b01, (outs SP:$rd_wb),
-                            (ins SP:$rd, simm10_lsb0000:$imm),
+                            (ins SP:$rd, simm10_lsb0000nonzero:$imm),
                             "c.addi16sp", "$rd, $imm"> {
   let Constraints = "$rd = $rd_wb";
   let Inst{12} = imm{9};
Index: llvm/trunk/test/MC/RISCV/rv32c-invalid.s
===================================================================
--- llvm/trunk/test/MC/RISCV/rv32c-invalid.s
+++ llvm/trunk/test/MC/RISCV/rv32c-invalid.s
@@ -45,9 +45,13 @@
 
 ## simm6
 c.li t0, 128 # CHECK: :[[@LINE]]:10: error: immediate must be an integer in the range [-32, 31]
-c.addi t0, 32 # CHECK: :[[@LINE]]:12: error: immediate must be an integer in the range [-32, 31]
 c.andi a0, -33 # CHECK: :[[@LINE]]:12: error: immediate must be an integer in the range [-32, 31]
 
+## simm6nonzero
+c.addi t0, 0 # CHECK: :[[@LINE]]:12: error: immediate must be non-zero in the range [-32, 31]
+c.addi t0, -33 # CHECK: :[[@LINE]]:12: error: immediate must be non-zero in the range [-32, 31]
+c.addi t0, 32 # CHECK: :[[@LINE]]:12: error: immediate must be non-zero in the range [-32, 31]
+
 ## uimm6nonzero
 c.lui t0, 64 # CHECK: :[[@LINE]]:11: error: immediate must be an integer in the range [1, 63]
 c.lui t0, 0 # CHECK: :[[@LINE]]:11: error: immediate must be an integer in the range [1, 63]
@@ -71,6 +75,7 @@
 c.addi4spn  a0, sp, 0 # CHECK: :[[@LINE]]:21: error: immediate must be a multiple of 4 bytes in the range [4, 1020]
 c.addi4spn  a0, sp, 1024 # CHECK: :[[@LINE]]:21: error: immediate must be a multiple of 4 bytes in the range [4, 1020]
 
-## simm10_lsb0000
-c.addi16sp  sp, -528 # CHECK: :[[@LINE]]:17: error: immediate must be a multiple of 16 bytes in the range [-512, 496]
-c.addi16sp  sp, 512 # CHECK: :[[@LINE]]:17: error: immediate must be a multiple of 16 bytes in the range [-512, 496]
+## simm10_lsb0000nonzero
+c.addi16sp  sp, -528 # CHECK: :[[@LINE]]:17: error: immediate must be a multiple of 16 bytes and non-zero in the range [-512, 496]
+c.addi16sp  sp, 512 # CHECK: :[[@LINE]]:17: error: immediate must be a multiple of 16 bytes and non-zero in the range [-512, 496]
+c.addi16sp  sp, 0 # CHECK: :[[@LINE]]:17: error: immediate must be a multiple of 16 bytes and non-zero in the range [-512, 496]