6 files changed, 81 insertions, 4 deletions

diff --git a/llvm/lib/Target/RISCV/RISCV.td b/llvm/lib/Target/RISCV/RISCV.td
index da919acad36..d8581f8d03c 100644
--- a/llvm/lib/Target/RISCV/RISCV.td
+++ b/llvm/lib/Target/RISCV/RISCV.td
@@ -13,11 +13,16 @@ include "llvm/Target/Target.td"
 // RISC-V subtarget features and instruction predicates.
 //===----------------------------------------------------------------------===//
 
-def Feature64Bit : SubtargetFeature<"64bit", "HasRV64", "true",
-                                    "Implements RV64">;
+def FeatureStdExtM : SubtargetFeature<"m", "HasStdExtM", "true",
+                           "'M' (Integer Multiplication and Division)">;
+def HasStdExtM     : Predicate<"Subtarget->hasStdExtM()">,
+                           AssemblerPredicate<"FeatureStdExtM">;
 
-def RV64         : HwMode<"+64bit">;
-def RV32         : HwMode<"-64bit">;
+def Feature64Bit   : SubtargetFeature<"64bit", "HasRV64", "true",
+                           "Implements RV64">;
+
+def RV64           : HwMode<"+64bit">;
+def RV32           : HwMode<"-64bit">;
 
 //===----------------------------------------------------------------------===//
 // Registers, calling conventions, instruction descriptions.
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.td b/llvm/lib/Target/RISCV/RISCVInstrInfo.td
index 23f218fda8f..e95a8e1c813 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.td
@@ -399,3 +399,9 @@ def ADJCALLSTACKDOWN : Pseudo<(outs), (ins i32imm:$amt1, i32imm:$amt2),
 def ADJCALLSTACKUP   : Pseudo<(outs), (ins i32imm:$amt1, i32imm:$amt2),
                               [(CallSeqEnd timm:$amt1, timm:$amt2)]>;
 } // Defs = [X2], Uses = [X2]
+
+//===----------------------------------------------------------------------===//
+// Standard extensions
+//===----------------------------------------------------------------------===//
+
+include "RISCVInstrInfoM.td"
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoM.td b/llvm/lib/Target/RISCV/RISCVInstrInfoM.td
new file mode 100644
index 00000000000..a253c1eb811
--- /dev/null
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoM.td
@@ -0,0 +1,28 @@
+//===-- RISCVInstrInfoM.td - RISC-V 'M' instructions -------*- tablegen -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file describes the RISC-V instructions from the standard 'M', Integer
+// Multiplication and Division instruction set extension.
+//
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+// Instructions
+//===----------------------------------------------------------------------===//
+
+let Predicates = [HasStdExtM] in {
+def MUL     : ALU_rr<0b0000001, 0b000, "mul">;
+def MULH    : ALU_rr<0b0000001, 0b001, "mulh">;
+def MULHSU  : ALU_rr<0b0000001, 0b010, "mulhsu">;
+def MULHU   : ALU_rr<0b0000001, 0b011, "mulhu">;
+def DIV     : ALU_rr<0b0000001, 0b100, "div">;
+def DIVU    : ALU_rr<0b0000001, 0b101, "divu">;
+def REM     : ALU_rr<0b0000001, 0b110, "rem">;
+def REMU    : ALU_rr<0b0000001, 0b111, "remu">;
+} // Predicates = [HasStdExtM]
diff --git a/llvm/lib/Target/RISCV/RISCVSubtarget.h b/llvm/lib/Target/RISCV/RISCVSubtarget.h
index 657b0e65620..be9b04990ca 100644
--- a/llvm/lib/Target/RISCV/RISCVSubtarget.h
+++ b/llvm/lib/Target/RISCV/RISCVSubtarget.h
@@ -30,6 +30,7 @@ class StringRef;
 
 class RISCVSubtarget : public RISCVGenSubtargetInfo {
   virtual void anchor();
+  bool HasStdExtM;
   bool HasRV64 = false;
   unsigned XLen = 32;
   MVT XLenVT = MVT::i32;
@@ -66,6 +67,7 @@ public:
   const SelectionDAGTargetInfo *getSelectionDAGInfo() const override {
     return &TSInfo;
   }
+  bool hasStdExtM() const { return HasStdExtM; }
   bool is64Bit() const { return HasRV64; }
   MVT getXLenVT() const { return XLenVT; }
   unsigned getXLen() const { return XLen; }
diff --git a/llvm/test/MC/RISCV/rv32i-invalid.s b/llvm/test/MC/RISCV/rv32i-invalid.s
index 3e4ac85ed60..763d4c547a2 100644
--- a/llvm/test/MC/RISCV/rv32i-invalid.s
+++ b/llvm/test/MC/RISCV/rv32i-invalid.s
@@ -128,3 +128,6 @@ lw a4, a5, 111 # CHECK: :[[@LINE]]:8: error: immediate must be an integer in the
 # Too few operands
 ori a0, a1 # CHECK: :[[@LINE]]:1: error: too few operands for instruction
 xor s2, s2 # CHECK: :[[@LINE]]:1: error: too few operands for instruction
+
+# Instruction not in the base ISA
+mul a4, ra, s0 # CHECK: :[[@LINE]]:1: error: instruction use requires an option to be enabled
diff --git a/llvm/test/MC/RISCV/rv32m-valid.s b/llvm/test/MC/RISCV/rv32m-valid.s
new file mode 100644
index 00000000000..70c1c29d3ad
--- /dev/null
+++ b/llvm/test/MC/RISCV/rv32m-valid.s
@@ -0,0 +1,33 @@
+# RUN: llvm-mc %s -triple=riscv32 -mattr=+m -show-encoding \
+# RUN:     | FileCheck -check-prefixes=CHECK,CHECK-INST %s
+# RUN: llvm-mc %s -triple=riscv64 -mattr=+m -show-encoding \
+# RUN:     | FileCheck -check-prefixes=CHECK,CHECK-INST %s
+# RUN: llvm-mc -filetype=obj -triple riscv32 -mattr=+m < %s \
+# RUN:     | llvm-objdump -mattr=+m -d - | FileCheck -check-prefix=CHECK-INST %s
+# RUN: llvm-mc -filetype=obj -triple riscv64 -mattr=+m < %s \
+# RUN:     | llvm-objdump -mattr=+m -d - | FileCheck -check-prefix=CHECK-INST %s
+
+# CHECK-INST: mul a4, ra, s0
+# CHECK: encoding: [0x33,0x87,0x80,0x02]
+mul a4, ra, s0
+# CHECK-INST: mulh ra, zero, zero
+# CHECK: encoding: [0xb3,0x10,0x00,0x02]
+mulh x1, x0, x0
+# CHECK-INST: mulhsu t0, t2, t1
+# CHECK: encoding: [0xb3,0xa2,0x63,0x02]
+mulhsu t0, t2, t1
+# CHECK-INST: mulhu a5, a4, a3
+# CHECK: encoding: [0xb3,0x37,0xd7,0x02]
+mulhu a5, a4, a3
+# CHECK-INST: div s0, s0, s0
+# CHECK: encoding: [0x33,0x44,0x84,0x02]
+div s0, s0, s0
+# CHECK-INST: divu gp, a0, a1
+# CHECK: encoding: [0xb3,0x51,0xb5,0x02]
+divu gp, a0, a1
+# CHECK-INST: rem s2, s2, s8
+# CHECK: encoding: [0x33,0x69,0x89,0x03]
+rem s2, s2, s8
+# CHECK-INST: remu s2, s2, s8
+# CHECK: encoding: [0x33,0x79,0x89,0x03]
+remu x18, x18, x24