[llvm] [RISCV] Add getFeaturesForCPU function support (PR #83269)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-risc-v

Author: Brandon Wu (4vtomat)

<details>
<summary>Changes</summary>

This function parse the cpu and return it's supported
features placed in EnabledFeatures. It is same as the
one in X86TargetParser and also is used in IREE.


---
Full diff: https://github.com/llvm/llvm-project/pull/83269.diff


2 Files Affected:

- (modified) llvm/include/llvm/TargetParser/RISCVTargetParser.h (+3) 
- (modified) llvm/lib/TargetParser/RISCVTargetParser.cpp (+27) 


``````````diff
diff --git a/llvm/include/llvm/TargetParser/RISCVTargetParser.h b/llvm/include/llvm/TargetParser/RISCVTargetParser.h
index e7da677c7d3ead..553b4efe0e3038 100644
--- a/llvm/include/llvm/TargetParser/RISCVTargetParser.h
+++ b/llvm/include/llvm/TargetParser/RISCVTargetParser.h
@@ -25,6 +25,9 @@ namespace RISCV {
 // We use 64 bits as the known part in the scalable vector types.
 static constexpr unsigned RVVBitsPerBlock = 64;
 
+void getFeaturesForCPU(StringRef CPU,
+                       SmallVectorImpl<std::string> &EnabledFeatures,
+                       bool NeedPlus = false);
 bool parseCPU(StringRef CPU, bool IsRV64);
 bool parseTuneCPU(StringRef CPU, bool IsRV64);
 StringRef getMArchFromMcpu(StringRef CPU);
diff --git a/llvm/lib/TargetParser/RISCVTargetParser.cpp b/llvm/lib/TargetParser/RISCVTargetParser.cpp
index 85cdd1289a9538..24a1e088d2df8b 100644
--- a/llvm/lib/TargetParser/RISCVTargetParser.cpp
+++ b/llvm/lib/TargetParser/RISCVTargetParser.cpp
@@ -14,6 +14,7 @@
 #include "llvm/TargetParser/RISCVTargetParser.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/Support/RISCVISAInfo.h"
 #include "llvm/TargetParser/Triple.h"
 
 namespace llvm {
@@ -95,5 +96,31 @@ void fillValidTuneCPUArchList(SmallVectorImpl<StringRef> &Values, bool IsRV64) {
 #include "llvm/TargetParser/RISCVTargetParserDef.inc"
 }
 
+void getFeaturesForCPU(StringRef CPU,
+                       SmallVectorImpl<std::string> &EnabledFeatures,
+                       bool NeedPlus) {
+  StringRef MarchFromCPU = llvm::RISCV::getMArchFromMcpu(CPU);
+  if (MarchFromCPU == "")
+    return;
+
+  EnabledFeatures.clear();
+  auto RII = RISCVISAInfo::parseArchString(
+      MarchFromCPU, /* EnableExperimentalExtension */ true);
+
+  if (llvm::errorToBool(RII.takeError()))
+    return;
+
+  std::vector<std::string> FeatStrings =
+      (*RII)->toFeatures(/* AddAllExtensions */ true);
+  for (const auto &F : FeatStrings) {
+    if (F[0] == '-')
+      continue;
+
+    if (NeedPlus)
+      EnabledFeatures.push_back(F);
+    else
+      EnabledFeatures.push_back(F.substr(1, F.size() - 1));
+  }
+}
 } // namespace RISCV
 } // namespace llvm

``````````

</details>


https://github.com/llvm/llvm-project/pull/83269