[clang] [RISCV] Replace 'native' before applying features for -mtune=native:<feature_list> (PR #215891)
Craig Topper via cfe-commits
cfe-commits at lists.llvm.org
Fri Aug 14 14:48:45 PDT 2026
https://github.com/topperc updated https://github.com/llvm/llvm-project/pull/215891
>From a1ab08be4b3f356ed476229207d2a496f5138abd Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Wed, 12 Aug 2026 10:55:36 -0700
Subject: [PATCH 1/3] [RISCV] Diagnose -mtune CPU with a : and no features as
requiring -mexperimental-mtune-syntax.
Without -mexperimental-mtune-syntax -mtune=sifive-x280: was considering
sifive-x280: as the full CPU name. With this patch we now diagnose any use
of the : even if there's nothing after it.
---
clang/lib/Driver/ToolChains/Arch/RISCV.cpp | 17 ++++++++++-------
clang/test/Driver/riscv-mtune-tune-features.c | 5 +++++
2 files changed, 15 insertions(+), 7 deletions(-)
diff --git a/clang/lib/Driver/ToolChains/Arch/RISCV.cpp b/clang/lib/Driver/ToolChains/Arch/RISCV.cpp
index c90d771e87a23..a1bf62f80589c 100644
--- a/clang/lib/Driver/ToolChains/Arch/RISCV.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/RISCV.cpp
@@ -404,22 +404,25 @@ riscv::getRISCVTuneCPU(const Driver &D, const llvm::opt::ArgList &Args,
if (!MTuneArg)
return "";
- StringRef MTune = MTuneArg->getValue();
- // Split the CPU name part from the tune features string.
- auto [TuneCPU, TFString] = MTune.split(':');
- if (!Args.hasFlag(options::OPT_mexperimental_mtune_syntax,
+ StringRef TuneCPU = MTuneArg->getValue();
+ StringRef TFString;
+
+ auto Idx = TuneCPU.find(':');
+ if (Idx != StringRef::npos) {
+ if (!Args.hasFlag(options::OPT_mexperimental_mtune_syntax,
options::OPT_mno_experimental_mtune_syntax, false)) {
- if (!TFString.empty()) {
// Only print this diagnostics if it's used for retrieving tune features
// to avoid printing the same error message multiple times.
if (TuneFeatures)
D.Diag(diag::err_drv_invalid_riscv_mtune_string)
- << 0 << MTune
+ << 0 << TuneCPU
<< "require '-mexperimental-mtune-syntax' to use with tune feature "
"string";
return std::nullopt;
}
- return MTune;
+
+ TFString = TuneCPU.substr(Idx + 1);
+ TuneCPU = TuneCPU.slice(0, Idx);
}
if (!TuneFeatures || TFString.empty())
diff --git a/clang/test/Driver/riscv-mtune-tune-features.c b/clang/test/Driver/riscv-mtune-tune-features.c
index e31500cf9d20a..bb55443b51c8e 100644
--- a/clang/test/Driver/riscv-mtune-tune-features.c
+++ b/clang/test/Driver/riscv-mtune-tune-features.c
@@ -19,6 +19,11 @@
// RUN: FileCheck --check-prefix=NO-EXPERIMENTAL %s
// NO-EXPERIMENTAL: invalid -mtune string 'sifive-x390:full-vec-fp64':
// NO-EXPERIMENTAL-SAME: require '-mexperimental-mtune-syntax' to use with tune feature string
+//
+// RUN: not %clang --target=riscv64 -mtune=sifive-x390: -c %s 2>&1 | \
+// RUN: FileCheck --check-prefix=NO-EXPERIMENTAL2 %s
+// NO-EXPERIMENTAL2: invalid -mtune string 'sifive-x390:':
+// NO-EXPERIMENTAL2-SAME: require '-mexperimental-mtune-syntax' to use with tune feature string
// RUN: not %clang --target=riscv64 -mexperimental-mtune-syntax \
// RUN: -mtune=sifive-p470:full-vec-fp64 -c %s 2>&1 | \
>From 45164199aee0ff17557ae530744548141635b8ed Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Wed, 12 Aug 2026 13:31:16 -0700
Subject: [PATCH 2/3] [RISCV] Replace 'native' before applying features for
-mtune=native:<feature_list>
We need to replace the CPU before calling parseTuneFeatureString or
it will always fails.
---
clang/lib/Driver/ToolChains/Arch/RISCV.cpp | 3 +++
clang/lib/Driver/ToolChains/Clang.cpp | 9 +++------
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/clang/lib/Driver/ToolChains/Arch/RISCV.cpp b/clang/lib/Driver/ToolChains/Arch/RISCV.cpp
index a1bf62f80589c..06dbb9d7ac0c4 100644
--- a/clang/lib/Driver/ToolChains/Arch/RISCV.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/RISCV.cpp
@@ -425,6 +425,9 @@ riscv::getRISCVTuneCPU(const Driver &D, const llvm::opt::ArgList &Args,
TuneCPU = TuneCPU.slice(0, Idx);
}
+ if (TuneCPU == "native")
+ TuneCPU = llvm::sys::getHostCPUName();
+
if (!TuneFeatures || TFString.empty())
return TuneCPU;
if (auto E = llvm::RISCV::parseTuneFeatureString(TuneCPU, TFString,
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index e8760d0d7a3aa..ca89ef4a3109b 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2034,12 +2034,9 @@ void Clang::AddRISCVTargetArgs(const ArgList &Args,
return;
if (!TuneCPU->empty()) {
CmdArgs.push_back("-tune-cpu");
- if (*TuneCPU == "native")
- CmdArgs.push_back(Args.MakeArgString(llvm::sys::getHostCPUName()));
- else
- // TuneCPU might or might not be the original -mtune string, so we
- // have to create a new copy here.
- CmdArgs.push_back(Args.MakeArgString(*TuneCPU));
+ // TuneCPU might or might not be the original -mtune string, so we
+ // have to create a new copy here.
+ CmdArgs.push_back(Args.MakeArgString(*TuneCPU));
}
// Handle -mrvv-vector-bits=<bits>
>From b4d80952669daadabb8942111b41024d155404a7 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Fri, 14 Aug 2026 14:43:10 -0700
Subject: [PATCH 3/3] fixup! Move native after parseTuneFeatureString.
---
clang/lib/Driver/ToolChains/Arch/RISCV.cpp | 21 +++++++++++--------
clang/test/Driver/riscv-mtune-tune-features.c | 6 ++++++
2 files changed, 18 insertions(+), 9 deletions(-)
diff --git a/clang/lib/Driver/ToolChains/Arch/RISCV.cpp b/clang/lib/Driver/ToolChains/Arch/RISCV.cpp
index 06dbb9d7ac0c4..f5315ebfc5f2c 100644
--- a/clang/lib/Driver/ToolChains/Arch/RISCV.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/RISCV.cpp
@@ -425,17 +425,20 @@ riscv::getRISCVTuneCPU(const Driver &D, const llvm::opt::ArgList &Args,
TuneCPU = TuneCPU.slice(0, Idx);
}
+ if (TuneFeatures && !TFString.empty()) {
+ if (auto E = llvm::RISCV::parseTuneFeatureString(TuneCPU, TFString,
+ *TuneFeatures)) {
+ D.Diag(diag::err_drv_invalid_riscv_mtune_string)
+ << 1 << TFString << llvm::toString(std::move(E));
+ return std::nullopt;
+ }
+ }
+
+ // Apply -mtune=native after applying features. Not all features apply to
+ // all CPUs so an -mtune=native:<feature> may fail depending on what the
+ // native was expanded to.
if (TuneCPU == "native")
TuneCPU = llvm::sys::getHostCPUName();
- if (!TuneFeatures || TFString.empty())
- return TuneCPU;
- if (auto E = llvm::RISCV::parseTuneFeatureString(TuneCPU, TFString,
- *TuneFeatures)) {
- D.Diag(diag::err_drv_invalid_riscv_mtune_string)
- << 1 << TFString << llvm::toString(std::move(E));
- return std::nullopt;
- }
-
return TuneCPU;
}
diff --git a/clang/test/Driver/riscv-mtune-tune-features.c b/clang/test/Driver/riscv-mtune-tune-features.c
index bb55443b51c8e..f674243097a8f 100644
--- a/clang/test/Driver/riscv-mtune-tune-features.c
+++ b/clang/test/Driver/riscv-mtune-tune-features.c
@@ -42,3 +42,9 @@
// RUN: FileCheck --check-prefix=UNSUPPORTED-DIRECTIVE %s
// UNSUPPORTED-DIRECTIVE: invalid tune feature string 'prefer-w-inst':
// UNSUPPORTED-DIRECTIVE-SAME: Directive 'prefer-w-inst' is not allowed to be used with processor 'sifive-x280'
+
+// RUN: not %clang --target=riscv64 -mexperimental-mtune-syntax \
+// RUN: -mtune=native:full-vec-fp64 -c %s 2>&1 | \
+// RUN: FileCheck --check-prefix=NO-DIRECTIVE-NATIVE %s
+// NO-DIRECTIVE-NATIVE: invalid tune feature string 'full-vec-fp64':
+// NO-DIRECTIVE-NATIVE-SAME: Processor 'native' has no configurable tuning features
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