llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Piyou Chen (BeMg)
<details>
<summary>Changes</summary>
This patch aims to replace the target attribute override mechanism based on
`__RISCV_TargetAttrNeedOverride` with the insertion of several negative target
features
When the target attribute uses the full architecture string ("arch=rv64gc") or
specifies the CPU ("cpu=rocket-rv64") as the version, it will override the
module-level target feature. Currently, this mechanism is implemented by
inserting `__RISCV_TargetAttrNeedOverride` as a dummy target feature
immediately before the target attribute's feature.
```
module target features + __RISCV_TargetAttrNeedOverride + target attribute's
feature
```
The RISCVTargetInfo::initFeatureMap function will remove the "module target
features" and use only the "target attribute's features".
This patch changes the process as follows:
```
module target features + negative target feature for all supported extension +
target attribute's feature
```
The `module target features` will be disable by `negative target feature for
all supported extension` in `TargetInfo::initFeatureMap`
---
Full diff: https://github.com/llvm/llvm-project/pull/106680.diff
1 Files Affected:
- (modified) clang/lib/Basic/Targets/RISCV.cpp (+13-20)
``````````diff
diff --git a/clang/lib/Basic/Targets/RISCV.cpp
b/clang/lib/Basic/Targets/RISCV.cpp
index 1f8a8cd1462c9d..b89109e7725d44 100644
--- a/clang/lib/Basic/Targets/RISCV.cpp
+++ b/clang/lib/Basic/Targets/RISCV.cpp
@@ -255,25 +255,6 @@ bool RISCVTargetInfo::initFeatureMap(
Features["32bit"] = true;
}
- // If a target attribute specified a full arch string, override all the ISA
- // extension target features.
- const auto I = llvm::find(FeaturesVec, "__RISCV_TargetAttrNeedOverride");
- if (I != FeaturesVec.end()) {
- std::vector<std::string> OverrideFeatures(std::next(I), FeaturesVec.end());
-
- // Add back any non ISA extension features, e.g. +relax.
- auto IsNonISAExtFeature = [](StringRef Feature) {
- assert(Feature.size() > 1 && (Feature[0] == '+' || Feature[0] == '-'));
- StringRef Ext = Feature.substr(1); // drop the +/-
- return !llvm::RISCVISAInfo::isSupportedExtensionFeature(Ext);
- };
- llvm::copy_if(llvm::make_range(FeaturesVec.begin(), I),
- std::back_inserter(OverrideFeatures), IsNonISAExtFeature);
-
- return TargetInfo::initFeatureMap(Features, Diags, CPU, OverrideFeatures);
- }
-
- // Otherwise, parse the features and add any implied extensions.
std::vector<std::string> AllFeatures = FeaturesVec;
auto ParseResult = llvm::RISCVISAInfo::parseFeatures(XLen, FeaturesVec);
if (!ParseResult) {
@@ -389,9 +370,20 @@ void RISCVTargetInfo::fillValidTuneCPUList(
llvm::RISCV::fillValidTuneCPUArchList(Values, Is64Bit);
}
+static void populateNegativeRISCVFeatures(std::vector<std::string> &Features) {
+ auto RII = llvm::RISCVISAInfo::parseArchString(
+ "rv64i", /* EnableExperimentalExtension */ true);
+
+ if (llvm::errorToBool(RII.takeError()))
+ llvm_unreachable("unsupport rv64i");
+
+ std::vector<std::string> FeatStrings =
+ (*RII)->toFeatures(/* AddAllExtensions */ true);
+ Features.insert(Features.end(), FeatStrings.begin(), FeatStrings.end());
+}
+
static void handleFullArchString(StringRef FullArchStr,
std::vector<std::string> &Features) {
- Features.push_back("__RISCV_TargetAttrNeedOverride");
auto RII = llvm::RISCVISAInfo::parseArchString(
FullArchStr, /* EnableExperimentalExtension */ true);
if (llvm::errorToBool(RII.takeError())) {
@@ -400,6 +392,7 @@ static void handleFullArchString(StringRef FullArchStr,
} else {
// Append a full list of features, including any negative extensions so
that
// we override the CPU's features.
+ populateNegativeRISCVFeatures(Features);
std::vector<std::string> FeatStrings =
(*RII)->toFeatures(/* AddAllExtensions */ true);
Features.insert(Features.end(), FeatStrings.begin(), FeatStrings.end());
``````````
</details>
https://github.com/llvm/llvm-project/pull/106680
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