[Driver] allow target override containing . in executable name

[dankm]

Summary

The gcc compatible driver has support for overriding the default
target based on the driver's executable name, for instance
x86_64-pc-linux-gnu-clang will set the default target to
x86_64-pc-linux-gnu.

Previously, this failed when the target contained a minor version, for
example x86_64-pc-freebsd13.1, so instead of finding the file's
stem, use the whole file name, but strip off any '.exe' from the tail.

[dankm]

I'd like comments on this approach to handle target names with a . in them. My assumption is that the way it was done (by finding the filename stem) was to strip any ".exe" string on Windows, but there may be other reasons.

[MaskRay]

The gcc compatible driver has support for selecting an alternative target based on the driver's executable name, for instance x86_64-unknown-linux-gnu-clang will set the target to linux on x86_64.

I think the somewhat canonical term is target override (not selecting an alternative target). This changes makes sense and I think it deserves a test in Driver/target-override.c (REQUIRE: shell is important for ln -s %clang ... to work).

Previously, this failed when the target contains a minor version, for example x86_64-unknown-freebsd13.1, so instead of finding the file's stem, use the whole file name, but strip off any '.exe' from the tail.

Mentioning the literal executable name helps readers understand the nature of the change. This change makes x86_64-pc-freebsd13.1-clang to be recognized as having a default target triple of x86_64-pc-freebsd13.1.

[dankm]

Thanks for the feedback. I've added a testcase for this, I'll push that change and update the summary.

[MaskRay]

In D135284#3886469, @dankm wrote:

Thanks for the feedback. I've added a testcase for this, I'll push that change and update the summary.

Did you upload a new patch to the differential? I cannot see it.

[dankm]

Added a simple testcase, and updated commit message.

[dankm]

In D135284#3886471, @MaskRay wrote:

In D135284#3886469, @dankm wrote:

Thanks for the feedback. I've added a testcase for this, I'll push that change and update the summary.

Did you upload a new patch to the differential? I cannot see it.

I hadn't. I posted that comment and then pushed a new patch.

[MaskRay]

Thanks!

[dankm]

Thanks! Since I don't have privileges to push, can you do that on my behalf?

clang/lib/Driver/ToolChain.cpp

for (const auto &DS : DriverSuffixes) {
     }
   }
   return nullptr;
 }
 
 /// Normalize the program name from argv[0] by stripping the file extension if
 /// present and lower-casing the string on Windows.
 static std::string normalizeProgramName(llvm::StringRef Argv0) {
-  std::string ProgName = std::string(llvm::sys::path::stem(Argv0));
+  std::string ProgName = std::string(llvm::sys::path::filename(Argv0));
   if (is_style_windows(llvm::sys::path::Style::native)) {
     // Transform to lowercase for case insensitive file systems.
     std::transform(ProgName.begin(), ProgName.end(), ProgName.begin(),
                    ::tolower);
   }
   return ProgName;
 }
 
 static const DriverSuffix *parseDriverSuffix(StringRef ProgName, size_t &Pos) {
   // Try to infer frontend type and default target from the program name by
   // comparing it against DriverSuffixes in order.
 
   // If there is a match, the function tries to identify a target as prefix.
   // E.g. "x86_64-linux-clang" as interpreted as suffix "clang" with target
   // prefix "x86_64-linux". If such a target prefix is found, it may be
   // added via -target as implicit first argument.
   const DriverSuffix *DS = FindDriverSuffix(ProgName, Pos);
 
+  if (!DS && ProgName.endswith(".exe")) {
+    // Try again after stripping the executable suffix:
+    // clang++.exe -> clang++
+    ProgName = ProgName.drop_back(StringRef(".exe").size());
+    DS = FindDriverSuffix(ProgName, Pos);
+  }
+
   if (!DS) {
     // Try again after stripping any trailing version number:
     // clang++3.5 -> clang++
     ProgName = ProgName.rtrim("0123456789.");
     DS = FindDriverSuffix(ProgName, Pos);
   }
 
   if (!DS) {

clang/test/Driver/target-override.c

 // REQUIRES: shell
 // REQUIRES: x86-registered-target
 
 // RUN: rm -rf %t && mkdir %t
 // RUN: ln -s %clang %t/i386-clang
+// RUN: ln -s %clang %t/x86_64-pc-freebsd13.1-clang
 
 // Check if invocation of "foo-clang" adds option "-target foo".
 //
 // RUN: %t/i386-clang -c -### %s 2>&1 | FileCheck -check-prefix CHECK-TG1 %s
 // CHECK-TG1: Target: i386
 
 // Check if invocation of "foo-clang --target=bar" overrides option "-target foo".
 //
 // RUN: %t/i386-clang -c --target=x86_64 -### %s 2>&1 | FileCheck -check-prefix CHECK-TG2 %s
 // CHECK-TG2: Target: x86_64
+
+/// Check if invocation of "arch-vendor-osX.Y-clang" adds option "-target arch-vendor-osX.Y".
+// RUN: %t/x86_64-pc-freebsd13.1-clang -c -### %s 2>&1 | FileCheck -check-prefix CHECK-TG3 %s
+// CHECK-TG3: Target: x86_64-pc-freebsd13.1