[RISCV] Add Qualcomm uC Xqcicsr (CSR) extension (#117169)

The Qualcomm uC Xqcicsr extension adds 2 instructions that can read and
write CSRs.

The current spec can be found at:
https://github.com/quic/riscv-unified-db/releases/latest

This patch adds assembler only support.

clang/test/Driver/print-supported-extensions-riscv.c

@@ -188,6 +188,7 @@
 // CHECK-NEXT:     smctr                1.0       'Smctr' (Control Transfer Records Machine Level)
 // CHECK-NEXT:     ssctr                1.0       'Ssctr' (Control Transfer Records Supervisor Level)
 // CHECK-NEXT:     svukte               0.3       'Svukte' (Address-Independent Latency of User-Mode Faults to Supervisor Addresses)
+// CHECK-NEXT:     xqcicsr              0.2       'Xqcicsr' (Qualcomm uC CSR Extension)
 // CHECK-EMPTY:
 // CHECK-NEXT: Supported Profiles
 // CHECK-NEXT:     rva20s64

llvm/docs/RISCVUsage.rst

@@ -426,6 +426,9 @@ The current vendor extensions supported are:
 ``Xwchc``
   LLVM implements `the custom compressed opcodes present in some QingKe cores` by WCH / Nanjing Qinheng Microelectronics. The vendor refers to these opcodes by the name "XW".
 
+``experimental-Xqcicsr``
+  LLVM implements `version 0.2 of the Qualcomm uC CSR extension specification <https://github.com/quic/riscv-unified-db/releases/latest>`__ by Qualcomm.  All instructions are prefixed with `qc.` as described in the specification. These instructions are only available for riscv32.
+
 Experimental C Intrinsics
 =========================
 

llvm/docs/ReleaseNotes.md

@@ -211,7 +211,8 @@ Changes to the RISC-V Backend
 * `f` and `cf` inline assembly constraints, when using F-/D-/H-in-X extensions,
   will use the relevant GPR rather than FPR. This makes inline assembly portable
   between e.g. F and Zfinx code.
-
+* Adds experimental assembler support for the Qualcomm uC 'Xqcicsr` (CSR)
+  extension.
 
 Changes to the WebAssembly Backend
 ----------------------------------

llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp

@@ -682,6 +682,8 @@ DecodeStatus RISCVDisassembler::getInstruction32(MCInst &MI, uint64_t &Size,
                         "CORE-V SIMD extensions custom opcode table");
   TRY_TO_DECODE_FEATURE(RISCV::FeatureVendorXCVbi, DecoderTableXCVbi32,
                         "CORE-V Immediate Branching custom opcode table");
+  TRY_TO_DECODE_FEATURE(RISCV::FeatureVendorXqcicsr, DecoderTableXqcicsr32,
+                        "Qualcomm uC CSR custom opcode table");
   TRY_TO_DECODE(true, DecoderTable32, "RISCV32 table");
 
   return MCDisassembler::Fail;

llvm/lib/Target/RISCV/RISCVFeatures.td

@@ -1341,6 +1341,16 @@ def HasVendorXwchc
       AssemblerPredicate<(all_of FeatureVendorXwchc),
                          "'Xwchc' (WCH/QingKe additional compressed opcodes)">;
 
+// Qualcomm Extension(s)
+
+def FeatureVendorXqcicsr
+    : RISCVExperimentalExtension<"xqcicsr", 0, 2,
+                                 "'Xqcicsr' (Qualcomm uC CSR Extension)">;
+def HasVendorXqcicsr
+    : Predicate<"Subtarget->hasVendorXqcicsr()">,
+      AssemblerPredicate<(all_of FeatureVendorXqcicsr),
+                         "'Xqcicsr' (Qualcomm uC CSR Extension)">;
+
 //===----------------------------------------------------------------------===//
 // LLVM specific features and extensions
 //===----------------------------------------------------------------------===//

llvm/lib/Target/RISCV/RISCVInstrInfo.td

@@ -2064,6 +2064,7 @@ include "RISCVInstrInfoXSf.td"
 include "RISCVInstrInfoSFB.td"
 include "RISCVInstrInfoXCV.td"
 include "RISCVInstrInfoXwch.td"
+include "RISCVInstrInfoXqci.td"
 
 //===----------------------------------------------------------------------===//
 // Global ISel

llvm/lib/Target/RISCV/RISCVInstrInfoXqci.td

@@ -0,0 +1,39 @@
+//===---------------- RISCVInstrInfoXQci.td ----------------*- tablegen -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file describes the vendor extensions defined by QUALCOMM.
+//
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+// Operand and SDNode transformation definitions.
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+// Instruction Formats
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+// Instruction Class Templates
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+// Instructions
+//===----------------------------------------------------------------------===//
+
+let Predicates = [HasVendorXqcicsr, IsRV32], DecoderNamespace = "Xqcicsr" in {
+let hasSideEffects = 0, mayLoad = 0, mayStore = 0 in {
+  def QC_CSRRWR : RVInstR<0b1000110, 0b000, OPC_SYSTEM, (outs GPR:$rd),
+                          (ins GPR:$rs1, GPRNoX0:$rs2), "qc.csrrwr",
+                          "$rd, $rs1, $rs2">;
+
+  def QC_CSRRWRI : RVInstR<0b1000111, 0b000, OPC_SYSTEM, (outs GPR:$rd),
+                           (ins uimm5:$rs1, GPRNoX0:$rs2), "qc.csrrwri",
+                           "$rd, $rs1, $rs2">;
+} // hasSideEffects = 0, mayLoad = 0, mayStore = 0
+} // Predicates = [HasVendorXqcicsr, IsRV32], DecoderNamespace = "Xqcicsr"

llvm/lib/TargetParser/RISCVISAInfo.cpp

@@ -771,6 +771,10 @@ Error RISCVISAInfo::checkDependency() {
       return getIncompatibleError("xwchc", "zcb");
   }
 
+  if (Exts.count("xqcicsr") != 0 && (XLen != 32)) {
+    return getError("'xqcicsr' is only supported for 'rv32'");
+  }
+
   return Error::success();
 }
 

llvm/test/CodeGen/RISCV/attributes.ll

@@ -81,6 +81,7 @@
 ; RUN: llc -mtriple=riscv32 -mattr=+xtheadmempair %s -o - | FileCheck --check-prefix=RV32XTHEADMEMPAIR %s
 ; RUN: llc -mtriple=riscv32 -mattr=+xtheadsync %s -o - | FileCheck --check-prefix=RV32XTHEADSYNC %s
 ; RUN: llc -mtriple=riscv32 -mattr=+xwchc %s -o - | FileCheck --check-prefix=RV32XWCHC %s
+; RUN: llc -mtriple=riscv32 -mattr=+experimental-xqcicsr %s -o - | FileCheck --check-prefix=RV32XQCICSR %s
 ; RUN: llc -mtriple=riscv32 -mattr=+zaamo %s -o - | FileCheck --check-prefix=RV32ZAAMO %s
 ; RUN: llc -mtriple=riscv32 -mattr=+zalrsc %s -o - | FileCheck --check-prefix=RV32ZALRSC %s
 ; RUN: llc -mtriple=riscv32 -mattr=+zca %s -o - | FileCheck --check-prefixes=CHECK,RV32ZCA %s
@@ -385,6 +386,7 @@
 ; RV32XTHEADMEMPAIR: .attribute 5, "rv32i2p1_xtheadmempair1p0"
 ; RV32XTHEADSYNC: .attribute 5, "rv32i2p1_xtheadsync1p0"
 ; RV32XWCHC: .attribute 5, "rv32i2p1_xwchc2p2"
+; RV32XQCICSR: .attribute 5, "rv32i2p1_xqcicsr0p2"
 ; RV32ZAAMO: .attribute 5, "rv32i2p1_zaamo1p0"
 ; RV32ZALRSC: .attribute 5, "rv32i2p1_zalrsc1p0"
 ; RV32ZCA: .attribute 5, "rv32i2p1_zca1p0"

llvm/test/MC/RISCV/xqcicsr-invalid.s

@@ -0,0 +1,27 @@
+# Xqcicsr - Qualcomm uC CSR Extension
+# RUN: not llvm-mc -triple riscv32 -mattr=+experimental-xqcicsr < %s 2>&1 \
+# RUN:     | FileCheck -check-prefixes=CHECK,CHECK-PLUS %s
+# RUN: not llvm-mc -triple riscv32 -mattr=-experimental-xqcicsr < %s 2>&1 \
+# RUN:     | FileCheck -check-prefixes=CHECK,CHECK-MINUS %s
+
+# CHECK: :[[@LINE+1]]:20: error: invalid operand for instruction
+qc.csrrwr x10, x5, x0
+
+# CHECK: :[[@LINE+1]]:1: error: too few operands for instruction
+qc.csrrwr x10, x5
+
+# CHECK-MINUS: :[[@LINE+1]]:1: error: instruction requires the following: 'Xqcicsr' (Qualcomm uC CSR Extension)
+qc.csrrwr x10, x5, x20
+
+
+# CHECK: :[[@LINE+1]]:21: error: invalid operand for instruction
+qc.csrrwri x20, 31, x0
+
+# CHECK-PLUS: :[[@LINE+1]]:17: error: immediate must be an integer in the range [0, 31]
+qc.csrrwri x20, 45, x12
+
+# CHECK: :[[@LINE+1]]:1: error: too few operands for instruction
+qc.csrrwri x20, 23
+
+# CHECK-MINUS: :[[@LINE+1]]:1: error: instruction requires the following: 'Xqcicsr' (Qualcomm uC CSR Extension)
+qc.csrrwri x30, 31, x12

llvm/test/MC/RISCV/xqcicsr-valid.s

@@ -0,0 +1,19 @@
+# Xqcicsr - Qualcomm uC CSR Extension
+# RUN: llvm-mc %s -triple=riscv32 -mattr=+experimental-xqcicsr -riscv-no-aliases -show-encoding \
+# RUN:     | FileCheck -check-prefixes=CHECK-ENC,CHECK-INST %s
+# RUN: llvm-mc -filetype=obj -triple riscv32 -mattr=+experimental-xqcicsr < %s \
+# RUN:     | llvm-objdump --mattr=+experimental-xqcicsr -M no-aliases --no-print-imm-hex -d - \
+# RUN:     | FileCheck -check-prefix=CHECK-INST %s
+# RUN: llvm-mc %s -triple=riscv32 -mattr=+experimental-xqcicsr -show-encoding \
+# RUN:     | FileCheck -check-prefixes=CHECK-ENC,CHECK-INST %s
+# RUN: llvm-mc -filetype=obj -triple riscv32 -mattr=+experimental-xqcicsr < %s \
+# RUN:     | llvm-objdump --mattr=+experimental-xqcicsr --no-print-imm-hex -d - \
+# RUN:     | FileCheck -check-prefix=CHECK-INST %s
+
+# CHECK-INST: qc.csrrwr  a0, t0, s4
+# CHECK-ENC: encoding: [0x73,0x85,0x42,0x8d]
+qc.csrrwr  x10, x5, x20
+
+# CHECK-INST: qc.csrrwri s4, 31, a2
+# CHECK-ENC: encoding: [0x73,0x8a,0xcf,0x8e]
+qc.csrrwri x20, 31, x12

llvm/unittests/TargetParser/RISCVISAInfoTest.cpp

@@ -1104,6 +1104,7 @@ Experimental extensions
     smctr                1.0
     ssctr                1.0
     svukte               0.3
+    xqcicsr              0.2
 
 Supported Profiles
     rva20s64