[flang][Driver] Add -masm option to flang (#81490)
The motivation here was a suggestion over in Compiler Explorer. You can
use `-mllvm` already to do this but since gfortran supports `-masm`, I
figured I'd try to add it.
This is done by flang expanding `-masm` into `-mllvm x86-asm-syntax=`,
then passing that to fc1. Which then collects all the `-mllvm` options
and forwards them on.
The code to expand it comes from clang `Clang::AddX86TargetArgs` (there
are some other places doing the same thing too). However I've removed
the `-inline-asm` that clang adds, as fortran doesn't have inline
assembly.
So `-masm` for flang purely changes the style of assembly output.
```
$ ./bin/flang-new /tmp/test.f90 -o - -S -target x86_64-linux-gnu
<...>
pushq %rbp
$ ./bin/flang-new /tmp/test.f90 -o - -S -target x86_64-linux-gnu -masm=att
<...>
pushq %rbp
$ ./bin/flang-new /tmp/test.f90 -o - -S -target x86_64-linux-gnu -masm=intel
<...>
push rbp
```
The test is adapted from `clang/test/Driver/masm.c` by removing the
clang-cl related lines and changing the 32 bit triples to 64 bit triples
since flang doesn't support 32 bit targets.diff --git a/clang/lib/Driver/ToolChains/Flang.cpp b/clang/lib/Driver/ToolChains/Flang.cpp
index 23da08a..6168b42d 100644
--- a/clang/lib/Driver/ToolChains/Flang.cpp
+++ b/clang/lib/Driver/ToolChains/Flang.cpp
@@ -249,6 +249,20 @@
}
}
+void Flang::AddX86_64TargetArgs(const ArgList &Args,
+ ArgStringList &CmdArgs) const {
+ if (Arg *A = Args.getLastArg(options::OPT_masm_EQ)) {
+ StringRef Value = A->getValue();
+ if (Value == "intel" || Value == "att") {
+ CmdArgs.push_back(Args.MakeArgString("-mllvm"));
+ CmdArgs.push_back(Args.MakeArgString("-x86-asm-syntax=" + Value));
+ } else {
+ getToolChain().getDriver().Diag(diag::err_drv_unsupported_option_argument)
+ << A->getSpelling() << Value;
+ }
+ }
+}
+
static void addVSDefines(const ToolChain &TC, const ArgList &Args,
ArgStringList &CmdArgs) {
@@ -374,6 +388,7 @@
break;
case llvm::Triple::x86_64:
getTargetFeatures(D, Triple, Args, CmdArgs, /*ForAs*/ false);
+ AddX86_64TargetArgs(Args, CmdArgs);
break;
}
