[RISCV] Add support for -mcpu option.

Summary:
1. gcc uses `-march` and `-mtune` flag to chose arch and
pipeline model, but clang does not have `-mtune` flag,
we uses `-mcpu` to chose both infos.
2. Add SiFive e31 and u54 cpu which have default march
and pipeline model.
3. Specific `-mcpu` with rocket-rv[32|64] would select
pipeline model only, and use the driver's arch choosing
logic to get default arch.

Reviewers: lenary, asb, evandro, HsiangKai

Reviewed By: lenary, asb, evandro

Tags: #llvm, #clang

Differential Revision: https://reviews.llvm.org/D71124

clang/lib/Basic/Targets/RISCV.cpp

@@ -13,6 +13,7 @@
 #include "RISCV.h"
 #include "clang/Basic/MacroBuilder.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/Support/TargetParser.h"
 
 using namespace clang;
 using namespace clang::targets;
@@ -166,3 +167,23 @@ bool RISCVTargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
 
   return true;
 }
+
+bool RISCV32TargetInfo::isValidCPUName(StringRef Name) const {
+  return llvm::RISCV::checkCPUKind(llvm::RISCV::parseCPUKind(Name),
+                                   /*Is64Bit=*/false);
+}
+
+void RISCV32TargetInfo::fillValidCPUList(
+    SmallVectorImpl<StringRef> &Values) const {
+  llvm::RISCV::fillValidCPUArchList(Values, false);
+}
+
+bool RISCV64TargetInfo::isValidCPUName(StringRef Name) const {
+  return llvm::RISCV::checkCPUKind(llvm::RISCV::parseCPUKind(Name),
+                                   /*Is64Bit=*/true);
+}
+
+void RISCV64TargetInfo::fillValidCPUList(
+    SmallVectorImpl<StringRef> &Values) const {
+  llvm::RISCV::fillValidCPUArchList(Values, true);
+}

clang/lib/Basic/Targets/RISCV.h

@@ -24,7 +24,7 @@ namespace targets {
 // RISC-V Target
 class RISCVTargetInfo : public TargetInfo {
 protected:
-  std::string ABI;
+  std::string ABI, CPU;
   bool HasM;
   bool HasA;
   bool HasF;
@@ -44,6 +44,13 @@ class RISCVTargetInfo : public TargetInfo {
     WIntType = UnsignedInt;
   }
 
+  bool setCPU(const std::string &Name) override {
+    if (!isValidCPUName(Name))
+      return false;
+    CPU = Name;
+    return true;
+  }
+
   StringRef getABI() const override { return ABI; }
   void getTargetDefines(const LangOptions &Opts,
                         MacroBuilder &Builder) const override;
@@ -97,6 +104,9 @@ class LLVM_LIBRARY_VISIBILITY RISCV32TargetInfo : public RISCVTargetInfo {
     return false;
   }
 
+  bool isValidCPUName(StringRef Name) const override;
+  void fillValidCPUList(SmallVectorImpl<StringRef> &Values) const override;
+
   void setMaxAtomicWidth() override {
     MaxAtomicPromoteWidth = 128;
 
@@ -121,6 +131,9 @@ class LLVM_LIBRARY_VISIBILITY RISCV64TargetInfo : public RISCVTargetInfo {
     return false;
   }
 
+  bool isValidCPUName(StringRef Name) const override;
+  void fillValidCPUList(SmallVectorImpl<StringRef> &Values) const override;
+
   void setMaxAtomicWidth() override {
     MaxAtomicPromoteWidth = 128;
 

clang/lib/Driver/ToolChains/Arch/RISCV.cpp

@@ -446,6 +446,19 @@ static bool getArchFeatures(const Driver &D, StringRef MArch,
   return true;
 }
 
+// Get features except standard extension feature
+void getRISCFeaturesFromMcpu(const Driver &D, const llvm::Triple &Triple,
+                             const llvm::opt::ArgList &Args,
+                             const llvm::opt::Arg *A, StringRef Mcpu,
+                             std::vector<StringRef> &Features) {
+  bool Is64Bit = (Triple.getArch() == llvm::Triple::riscv64);
+  llvm::RISCV::CPUKind CPUKind = llvm::RISCV::parseCPUKind(Mcpu);
+  if (!llvm::RISCV::checkCPUKind(CPUKind, Is64Bit) ||
+      !llvm::RISCV::getCPUFeaturesExceptStdExt(CPUKind, Features)) {
+    D.Diag(clang::diag::err_drv_clang_unsupported) << A->getAsString(Args);
+  }
+}
+
 void riscv::getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
                                    const ArgList &Args,
                                    std::vector<StringRef> &Features) {
@@ -454,6 +467,11 @@ void riscv::getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
   if (!getArchFeatures(D, MArch, Features, Args))
     return;
 
+  // If users give march and mcpu, get std extension feature from MArch
+  // and other features (ex. mirco architecture feature) from mcpu
+  if (Arg *A = Args.getLastArg(options::OPT_mcpu_EQ))
+    getRISCFeaturesFromMcpu(D, Triple, Args, A, A->getValue(), Features);
+
   // Handle features corresponding to "-ffixed-X" options
   if (Args.hasArg(options::OPT_ffixed_x1))
     Features.push_back("+reserve-x1");
@@ -543,11 +561,9 @@ StringRef riscv::getRISCVABI(const ArgList &Args, const llvm::Triple &Triple) {
 
   // GCC's logic around choosing a default `-mabi=` is complex. If GCC is not
   // configured using `--with-abi=`, then the logic for the default choice is
-  // defined in config.gcc. This function is based on the logic in GCC 9.2.0. We
-  // deviate from GCC's default only on baremetal targets (UnknownOS) where
-  // neither `-march` nor `-mabi` is specified.
+  // defined in config.gcc. This function is based on the logic in GCC 9.2.0.
   //
-  // The logic uses the following, in order:
+  // The logic used in GCC 9.2.0 is the following, in order:
   // 1. Explicit choices using `--with-abi=`
   // 2. A default based on `--with-arch=`, if provided
   // 3. A default based on the target triple's arch
@@ -556,38 +572,40 @@ StringRef riscv::getRISCVABI(const ArgList &Args, const llvm::Triple &Triple) {
   //
   // Clang does not have `--with-arch=` or `--with-abi=`, so we use `-march=`
   // and `-mabi=` respectively instead.
+  //
+  // In order to make chosing logic more clear, Clang uses the following logic,
+  // in order:
+  // 1. Explicit choices using `-mabi=`
+  // 2. A default based on the architecture as determined by getRISCVArch
+  // 3. Choose a default based on the triple
 
   // 1. If `-mabi=` is specified, use it.
   if (const Arg *A = Args.getLastArg(options::OPT_mabi_EQ))
     return A->getValue();
 
-  // 2. Choose a default based on `-march=`
+  // 2. Choose a default based on the target architecture.
   //
   // rv32g | rv32*d -> ilp32d
   // rv32e -> ilp32e
   // rv32* -> ilp32
   // rv64g | rv64*d -> lp64d
   // rv64* -> lp64
-  if (const Arg *A = Args.getLastArg(options::OPT_march_EQ)) {
-    StringRef MArch = A->getValue();
-
-    if (MArch.startswith_lower("rv32")) {
-      // FIXME: parse `March` to find `D` extension properly
-      if (MArch.substr(4).contains_lower("d") ||
-          MArch.startswith_lower("rv32g"))
-        return "ilp32d";
-      else if (MArch.startswith_lower("rv32e"))
-        return "ilp32e";
-      else
-        return "ilp32";
-    } else if (MArch.startswith_lower("rv64")) {
-      // FIXME: parse `March` to find `D` extension properly
-      if (MArch.substr(4).contains_lower("d") ||
-          MArch.startswith_lower("rv64g"))
-        return "lp64d";
-      else
-        return "lp64";
-    }
+  StringRef MArch = getRISCVArch(Args, Triple);
+
+  if (MArch.startswith_lower("rv32")) {
+    // FIXME: parse `March` to find `D` extension properly
+    if (MArch.substr(4).contains_lower("d") || MArch.startswith_lower("rv32g"))
+      return "ilp32d";
+    else if (MArch.startswith_lower("rv32e"))
+      return "ilp32e";
+    else
+      return "ilp32";
+  } else if (MArch.startswith_lower("rv64")) {
+    // FIXME: parse `March` to find `D` extension properly
+    if (MArch.substr(4).contains_lower("d") || MArch.startswith_lower("rv64g"))
+      return "lp64d";
+    else
+      return "lp64";
   }
 
   // 3. Choose a default based on the triple
@@ -617,10 +635,11 @@ StringRef riscv::getRISCVArch(const llvm::opt::ArgList &Args,
   // GCC's logic around choosing a default `-march=` is complex. If GCC is not
   // configured using `--with-arch=`, then the logic for the default choice is
   // defined in config.gcc. This function is based on the logic in GCC 9.2.0. We
-  // deviate from GCC's default only on baremetal targets (UnknownOS) where
-  // neither `-march` nor `-mabi` is specified.
+  // deviate from GCC's default on additional `-mcpu` option (GCC does not
+  // support `-mcpu`) and baremetal targets (UnknownOS) where neither `-march`
+  // nor `-mabi` is specified.
   //
-  // The logic uses the following, in order:
+  // The logic used in GCC 9.2.0 is the following, in order:
   // 1. Explicit choices using `--with-arch=`
   // 2. A default based on `--with-abi=`, if provided
   // 3. A default based on the target triple's arch
@@ -630,14 +649,28 @@ StringRef riscv::getRISCVArch(const llvm::opt::ArgList &Args,
   // Clang does not have `--with-arch=` or `--with-abi=`, so we use `-march=`
   // and `-mabi=` respectively instead.
   //
+  // Clang uses the following logic, in order:
+  // 1. Explicit choices using `-march=`
+  // 2. Based on `-mcpu` if the target CPU has a default ISA string
+  // 3. A default based on `-mabi`, if provided
+  // 4. A default based on the target triple's arch
+  //
   // Clang does not yet support MULTILIB_REUSE, so we use `rv{XLEN}imafdc`
   // instead of `rv{XLEN}gc` though they are (currently) equivalent.
 
   // 1. If `-march=` is specified, use it.
   if (const Arg *A = Args.getLastArg(options::OPT_march_EQ))
     return A->getValue();
 
-  // 2. Choose a default based on `-mabi=`
+  // 2. Get march (isa string) based on `-mcpu=`
+  if (const Arg *A = Args.getLastArg(options::OPT_mcpu_EQ)) {
+    StringRef MArch = llvm::RISCV::getMArchFromMcpu(A->getValue());
+    // Bypass if target cpu's default march is empty.
+    if (MArch != "")
+      return MArch;
+  }
+
+  // 3. Choose a default based on `-mabi=`
   //
   // ilp32e -> rv32e
   // ilp32 | ilp32f | ilp32d -> rv32imafdc
@@ -653,7 +686,7 @@ StringRef riscv::getRISCVArch(const llvm::opt::ArgList &Args,
       return "rv64imafdc";
   }
 
-  // 3. Choose a default based on the triple
+  // 4. Choose a default based on the triple
   //
   // We deviate from GCC's defaults here:
   // - On `riscv{XLEN}-unknown-elf` we default to `rv{XLEN}imac`

clang/lib/Driver/ToolChains/CommonArgs.cpp

@@ -333,6 +333,11 @@ std::string tools::getCPUName(const ArgList &Args, const llvm::Triple &T,
 
     return TargetCPUName;
   }
+  case llvm::Triple::riscv32:
+  case llvm::Triple::riscv64:
+    if (const Arg *A = Args.getLastArg(options::OPT_mcpu_EQ))
+      return A->getValue();
+    return "";
 
   case llvm::Triple::bpfel:
   case llvm::Triple::bpfeb:

clang/test/Driver/riscv-arch.c

@@ -156,9 +156,9 @@
 // RV32-LOWER: error: invalid arch name 'rv32imC',
 // RV32-LOWER: string must be lowercase
 
-// RUN: %clang -target riscv32-unknown-elf -march=rv32 -### %s \
+// RUN: %clang -target riscv32-unknown-elf -march=unknown -### %s \
 // RUN: -fsyntax-only 2>&1 | FileCheck -check-prefix=RV32-STR %s
-// RV32-STR: error: invalid arch name 'rv32',
+// RV32-STR: error: invalid arch name 'unknown',
 // RV32-STR: string must begin with rv32{i,e,g} or rv64{i,g}
 
 // RUN: %clang -target riscv32-unknown-elf -march=rv32q -### %s \

clang/test/Driver/riscv-cpus.c

@@ -0,0 +1,38 @@
+// Check target CPUs are correctly passed.
+
+// RUN: %clang -target riscv32 -### -c %s 2>&1 -mcpu=rocket-rv32 | FileCheck -check-prefix=MCPU-ROCKETCHIP32 %s
+// MCPU-ROCKETCHIP32: "-nostdsysteminc" "-target-cpu" "rocket-rv32"
+
+// RUN: %clang -target riscv64 -### -c %s 2>&1 -mcpu=rocket-rv64 | FileCheck -check-prefix=MCPU-ROCKETCHIP64 %s
+// MCPU-ROCKETCHIP64: "-nostdsysteminc" "-target-cpu" "rocket-rv64"
+// MCPU-ROCKETCHIP64: "-target-feature" "+64bit"
+
+// mcpu with default march
+// RUN: %clang -target riscv64 -### -c %s 2>&1 -mcpu=sifive-u54 | FileCheck -check-prefix=MCPU-SIFIVE-U54 %s
+// MCPU-SIFIVE-U54: "-nostdsysteminc" "-target-cpu" "sifive-u54"
+// MCPU-SIFIVE-U54: "-target-feature" "+m" "-target-feature" "+a" "-target-feature" "+f" "-target-feature" "+d"
+// MCPU-SIFIVE-U54: "-target-feature" "+c" "-target-feature" "+64bit"
+// MCPU-SIFIVE-U54: "-target-abi" "lp64d"
+
+// mcpu with mabi option
+// RUN: %clang -target riscv64 -### -c %s 2>&1 -mcpu=sifive-u54 -mabi=lp64 | FileCheck -check-prefix=MCPU-ABI-SIFIVE-U54 %s
+// MCPU-ABI-SIFIVE-U54: "-nostdsysteminc" "-target-cpu" "sifive-u54"
+// MCPU-ABI-SIFIVE-U54: "-target-feature" "+m" "-target-feature" "+a" "-target-feature" "+f" "-target-feature" "+d"
+// MCPU-ABI-SIFIVE-U54: "-target-feature" "+c" "-target-feature" "+64bit"
+// MCPU-ABI-SIFIVE-U54: "-target-abi" "lp64"
+
+// march overwirte mcpu's default march
+// RUN: %clang -target riscv32 -### -c %s 2>&1 -mcpu=sifive-e31 -march=rv32imc | FileCheck -check-prefix=MCPU-MARCH %s
+// MCPU-MARCH: "-nostdsysteminc" "-target-cpu" "sifive-e31" "-target-feature" "+m" "-target-feature" "+c"
+// MCPU-MARCH: "-target-abi" "ilp32"
+
+// Check failed cases
+
+// RUN: %clang -target riscv32 -### -c %s 2>&1 -mcpu=generic-rv321 | FileCheck -check-prefix=FAIL-MCPU-NAME %s
+// FAIL-MCPU-NAME: error: the clang compiler does not support '-mcpu=generic-rv321'
+
+// RUN: %clang -target riscv32 -### -c %s 2>&1 -mcpu=generic-rv32 -march=rv64i | FileCheck -check-prefix=MISMATCH-ARCH %s
+// MISMATCH-ARCH: error: the clang compiler does not support '-mcpu=generic-rv32'
+
+// RUN: %clang -target riscv32 -### -c %s 2>&1 -mcpu=generic-rv64 | FileCheck -check-prefix=MISMATCH-MCPU %s
+// MISMATCH-MCPU: error: the clang compiler does not support '-mcpu=generic-rv64'

clang/test/Misc/target-invalid-cpu-note.c

@@ -156,3 +156,10 @@
 // AVR-SAME: ttiny4, attiny5, attiny9, attiny10, attiny20, attiny40, attiny102,
 // AVR-SAME: attiny104
 
+// RUN: not %clang_cc1 -triple riscv32 -target-cpu not-a-cpu -fsyntax-only %s 2>&1 | FileCheck %s --check-prefix RISCV32
+// RISCV32: error: unknown target CPU 'not-a-cpu'
+// RISCV32: note: valid target CPU values are: generic-rv32, rocket-rv32, sifive-e31
+
+// RUN: not %clang_cc1 -triple riscv64 -target-cpu not-a-cpu -fsyntax-only %s 2>&1 | FileCheck %s --check-prefix RISCV64
+// RISCV64: error: unknown target CPU 'not-a-cpu'
+// RISCV64: note: valid target CPU values are: generic-rv64, rocket-rv64, sifive-u54

llvm/include/llvm/Support/RISCVTargetParser.def

@@ -0,0 +1,13 @@
+#ifndef PROC
+#define PROC(ENUM, NAME, FEATURES, DEFAULT_MARCH)
+#endif
+
+PROC(INVALID, {"invalid"}, FK_INVALID, {""})
+PROC(GENERIC_RV32, {"generic-rv32"}, FK_NONE, {""})
+PROC(GENERIC_RV64, {"generic-rv64"}, FK_64BIT, {""})
+PROC(ROCKET_RV32, {"rocket-rv32"}, FK_NONE, {""})
+PROC(ROCKET_RV64, {"rocket-rv64"}, FK_64BIT, {""})
+PROC(SIFIVE_E31, {"sifive-e31"}, FK_NONE, {"rv32imac"})
+PROC(SIFIVE_U54, {"sifive-u54"}, FK_64BIT, {"rv64gc"})
+
+#undef PROC

llvm/include/llvm/Support/TargetParser.h

@@ -130,6 +130,32 @@ IsaVersion getIsaVersion(StringRef GPU);
 
 } // namespace AMDGPU
 
+namespace RISCV {
+
+enum CPUKind : unsigned {
+#define PROC(ENUM, NAME, FEATURES, DEFAULT_MARCH) CK_##ENUM,
+#include "RISCVTargetParser.def"
+};
+
+enum FeatureKind : unsigned {
+  FK_INVALID = 0,
+  FK_NONE = 1,
+  FK_STDEXTM = 1 << 2,
+  FK_STDEXTA = 1 << 3,
+  FK_STDEXTF = 1 << 4,
+  FK_STDEXTD = 1 << 5,
+  FK_STDEXTC = 1 << 6,
+  FK_64BIT = 1 << 7,
+};
+
+bool checkCPUKind(CPUKind Kind, bool IsRV64);
+CPUKind parseCPUKind(StringRef CPU);
+StringRef getMArchFromMcpu(StringRef CPU);
+void fillValidCPUArchList(SmallVectorImpl<StringRef> &Values, bool IsRV64);
+bool getCPUFeaturesExceptStdExt(CPUKind Kind, std::vector<StringRef> &Features);
+
+} // namespace RISCV
+
 } // namespace llvm
 
 #endif