[clang] [Clang][RISCV] Recognize unsupport target feature by supporting... (PR #106495)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

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

Author: Piyou Chen (BeMg)

<details>
<summary>Changes</summary>

…isValidFeatureName

This patch makes unsupported target attributes emit a warning and ignore the target attribute during semantic checks. The changes include:

1. Adding the RISCVTargetInfo::isValidFeatureName function.
2. Adding a '+' sign to __RISCV_TargetAttrNeedOverride because checkTargetAttr will remove the sign.
3. Rejecting non-full-arch strings in the handleFullArchString function.
4. Adding test cases to demonstrate the warning behavior.



---
Full diff: https://github.com/llvm/llvm-project/pull/106495.diff


4 Files Affected:

- (modified) clang/lib/Basic/Targets/RISCV.cpp (+16-2) 
- (modified) clang/lib/Basic/Targets/RISCV.h (+1) 
- (modified) clang/lib/Sema/SemaDeclAttr.cpp (+11-4) 
- (modified) clang/test/Sema/attr-target-riscv.c (+9) 


``````````diff
diff --git a/clang/lib/Basic/Targets/RISCV.cpp b/clang/lib/Basic/Targets/RISCV.cpp
index 1f8a8cd1462c9d..1d6f49ca232692 100644
--- a/clang/lib/Basic/Targets/RISCV.cpp
+++ b/clang/lib/Basic/Targets/RISCV.cpp
@@ -257,7 +257,7 @@ bool RISCVTargetInfo::initFeatureMap(
 
   // If a target attribute specified a full arch string, override all the ISA
   // extension target features.
-  const auto I = llvm::find(FeaturesVec, "__RISCV_TargetAttrNeedOverride");
+  const auto I = llvm::find(FeaturesVec, "+__RISCV_TargetAttrNeedOverride");
   if (I != FeaturesVec.end()) {
     std::vector<std::string> OverrideFeatures(std::next(I), FeaturesVec.end());
 
@@ -391,7 +391,14 @@ void RISCVTargetInfo::fillValidTuneCPUList(
 
 static void handleFullArchString(StringRef FullArchStr,
                                  std::vector<std::string> &Features) {
-  Features.push_back("__RISCV_TargetAttrNeedOverride");
+
+  // Should be full arch string.
+  if (!FullArchStr.starts_with("rv")) {
+    Features.push_back(FullArchStr.str());
+    return;
+  }
+
+  Features.push_back("+__RISCV_TargetAttrNeedOverride");
   auto RII = llvm::RISCVISAInfo::parseArchString(
       FullArchStr, /* EnableExperimentalExtension */ true);
   if (llvm::errorToBool(RII.takeError())) {
@@ -485,3 +492,10 @@ bool RISCVTargetInfo::validateCpuSupports(StringRef Feature) const {
   // __riscv_feature_bits structure.
   return -1 != llvm::RISCVISAInfo::getRISCVFeaturesBitsInfo(Feature).second;
 }
+
+bool RISCVTargetInfo::isValidFeatureName(StringRef Name) const {
+  if (Name == "__RISCV_TargetAttrNeedOverride")
+    return true;
+
+  return llvm::RISCVISAInfo::isSupportedExtensionFeature(Name);
+}
diff --git a/clang/lib/Basic/Targets/RISCV.h b/clang/lib/Basic/Targets/RISCV.h
index 626274b8fc437c..b808ccc8e9cfe9 100644
--- a/clang/lib/Basic/Targets/RISCV.h
+++ b/clang/lib/Basic/Targets/RISCV.h
@@ -130,6 +130,7 @@ class RISCVTargetInfo : public TargetInfo {
   bool supportsCpuSupports() const override { return getTriple().isOSLinux(); }
   bool supportsCpuInit() const override { return getTriple().isOSLinux(); }
   bool validateCpuSupports(StringRef Feature) const override;
+  bool isValidFeatureName(StringRef Name) const override;
 };
 class LLVM_LIBRARY_VISIBILITY RISCV32TargetInfo : public RISCVTargetInfo {
 public:
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 1e074298ac5289..81cff8d7362ad5 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -2993,10 +2993,17 @@ bool Sema::checkTargetAttr(SourceLocation LiteralLoc, StringRef AttrStr) {
     return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
            << Unknown << Tune << ParsedAttrs.Tune << Target;
 
-  if (Context.getTargetInfo().getTriple().isRISCV() &&
-      ParsedAttrs.Duplicate != "")
-    return Diag(LiteralLoc, diag::err_duplicate_target_attribute)
-           << Duplicate << None << ParsedAttrs.Duplicate << Target;
+  if (Context.getTargetInfo().getTriple().isRISCV()) {
+    if (ParsedAttrs.Duplicate != "")
+      return Diag(LiteralLoc, diag::err_duplicate_target_attribute)
+             << Duplicate << None << ParsedAttrs.Duplicate << Target;
+    for (const auto &Feature : ParsedAttrs.Features) {
+      auto CurFeature = StringRef(Feature);
+      if (!CurFeature.starts_with("+") && !CurFeature.starts_with("-"))
+        return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
+               << Unsupported << None << AttrStr << Target;
+    }
+  }
 
   if (ParsedAttrs.Duplicate != "")
     return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
diff --git a/clang/test/Sema/attr-target-riscv.c b/clang/test/Sema/attr-target-riscv.c
index ed4e2915d6c6ef..01d928c1d78e48 100644
--- a/clang/test/Sema/attr-target-riscv.c
+++ b/clang/test/Sema/attr-target-riscv.c
@@ -4,3 +4,12 @@
 int __attribute__((target("arch=rv64g"))) foo(void) { return 0; }
 //expected-error at +1 {{redefinition of 'foo'}}
 int __attribute__((target("arch=rv64gc"))) foo(void) { return 0; }
+
+//expected-warning at +1 {{unsupported 'notafeature' in the 'target' attribute string; 'target' attribute ignored}}
+int __attribute__((target("arch=+notafeature"))) UnsupportFeature(void) { return 0; }
+
+//expected-warning at +1 {{unsupported 'arch=+zba,zbb' in the 'target' attribute string; 'target' attribute ignored}}
+int __attribute__((target("arch=+zba,zbb"))) WithoutAddSigned(void) { return 0; }
+
+//expected-warning at +1 {{unsupported 'arch=zba' in the 'target' attribute string; 'target' attribute ignored}}
+int __attribute__((target("arch=zba"))) WithoutAddSigned2(void) { return 0; }

``````````

</details>


https://github.com/llvm/llvm-project/pull/106495