[clang][Driver] Support passing arbitrary args to `-cc1as` with `-Xclangas`. (#100714)
Unlike the `-Xassembler` idea mentioned in #97517, this one comes with
no GCC compatibility concerns, and simply mirrors what `-Xclang` does
for `-cc1`.
This is useful for mostly the same reasons that `-Xclang` is. The
motivating use case is `zig cc`, however, where we use `-Xclang
-target-feature` to pass the exhaustive list of target features to Clang
for C-family files. Before this commit, there was no way to do the same
for assembly files.
For context, Zig bases all of its target feature info directly on the
info in LLVM's backends, including all the dependency relationships
therein. So it just makes more sense for Zig to be able to directly pass
all this info to the assembler, rather than having to manually
reconstruct the corresponding frontend command line flags for every
target.
Closes #97517.
diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
index 6925652..6c2053e 100644
--- a/clang/docs/UsersManual.rst
+++ b/clang/docs/UsersManual.rst
@@ -5146,6 +5146,7 @@
-v Show commands to run and use verbose output
-W<warning> Enable the specified warning
-Xclang <arg> Pass <arg> to the clang compiler
+ -Xclangas <arg> Pass <arg> to the clang assembler
The /clang: Option
^^^^^^^^^^^^^^^^^^
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 830d345..919c1c6 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -958,10 +958,18 @@
HelpText<"Pass <arg> to clang -cc1">, MetaVarName<"<arg>">,
Flags<[NoXarchOption]>, Visibility<[ClangOption, CLOption, DXCOption]>,
Group<CompileOnly_Group>;
+def Xclangas : Separate<["-"], "Xclangas">,
+ HelpText<"Pass <arg> to clang -cc1as">, MetaVarName<"<arg>">,
+ Flags<[NoXarchOption]>, Visibility<[ClangOption, CLOption, DXCOption]>,
+ Group<CompileOnly_Group>;
def : Joined<["-"], "Xclang=">, Group<CompileOnly_Group>,
Flags<[NoXarchOption]>, Visibility<[ClangOption, CLOption, DXCOption]>,
Alias<Xclang>,
HelpText<"Alias for -Xclang">, MetaVarName<"<arg>">;
+def : Joined<["-"], "Xclangas=">, Group<CompileOnly_Group>,
+ Flags<[NoXarchOption]>, Visibility<[ClangOption, CLOption, DXCOption]>,
+ Alias<Xclangas>,
+ HelpText<"Alias for -Xclangas">, MetaVarName<"<arg>">;
def Xcuda_fatbinary : Separate<["-"], "Xcuda-fatbinary">,
HelpText<"Pass <arg> to fatbinary invocation">, MetaVarName<"<arg>">;
def Xcuda_ptxas : Separate<["-"], "Xcuda-ptxas">,
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 67a800a..f2f5231 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -8895,6 +8895,12 @@
CollectArgsForIntegratedAssembler(C, Args, CmdArgs,
getToolChain().getDriver());
+ // Forward -Xclangas arguments to -cc1as
+ for (auto Arg : Args.filtered(options::OPT_Xclangas)) {
+ Arg->claim();
+ CmdArgs.push_back(Arg->getValue());
+ }
+
Args.AddAllArgs(CmdArgs, options::OPT_mllvm);
if (DebugInfoKind > llvm::codegenoptions::NoDebugInfo && Output.isFilename())
diff --git a/clang/test/Driver/Xclangas.s b/clang/test/Driver/Xclangas.s
new file mode 100644
index 0000000..0d39111
--- /dev/null
+++ b/clang/test/Driver/Xclangas.s
@@ -0,0 +1,4 @@
+/// Check that -Xclangas/-Xclangas= are passed to -cc1as.
+// RUN: %clang -### -Werror -Xclangas -target-feature -Xclangas=+v5t %s 2>&1 | FileCheck %s
+// CHECK: -cc1as
+// CHECK-SAME: "-target-feature" "+v5t"
