[PATCH] D111367: [Driver] Change -dumpmachine to respect --target/LLVM_DEFAULT_TARGET_TRIPLE verbatim

[Fangrui Song via Phabricator via cfe-commits]

MaskRay created this revision.
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This changed `-dumpmachine` does no normalization and follows GCC more closely
(`gcc -dumpmachine` on Debian may be `x86_64-linux-gnu`).

---

Vendors have different ideas on the canonical triple.
llvm/cmake/config.guess prefers x86_64-unknown-linux-gnu.
RedHat prefers x86_64-redhat-linux.
Suse prefers x86_64-suse-linux.
Debian/Ubuntu prefer x86_64-linux-gnu.

Traditionally they contribute their normalization rules to Triple.cpp or Clang
Driver. This is an unfortunate state: (a) less popular systems tend to patch Clang downstream
(b) Clang Driver has unneeded complexity.

To fix the unfortunate state, we should just respect
--target/LLVM_DEFAULT_TARGET_TRIPLE and do no normalization at all.
`-dumpmachine` can be handy when the user wants the configure-time LLVM_DEFAULT_TARGET_TRIPLE.

`--print-target-triple` still prints the normalized triple.
I think we probably should remove its usage in CMake compiler-rt in favor of `-dumpmachine`.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D111367

Files:
  clang/lib/Driver/Driver.cpp
  clang/test/Driver/dumpmachine.c


Index: clang/test/Driver/dumpmachine.c
===================================================================
--- /dev/null
+++ clang/test/Driver/dumpmachine.c
@@ -0,0 +1,16 @@
+/// Test that -dumpmachine prints the triple without normalization.
+
+/// config.guess may prefer x86_64-pc-linux-gnu, but we respect --target= verbatim.
+// RUN: %clang --target=x86_64-linux-gnu -dumpmachine | FileCheck %s --check-prefix=X86_64
+// X86_64: x86_64-linux-gnu
+
+/// Note: GCC doesn't convert -dumpmachine output for multilib -m32/-mx32/-m64.
+// RUN: %clang --target=x86_64-redhat-linux -m32 -dumpmachine | FileCheck %s --check-prefix=X86_64_M32
+// X86_64_M32: i386-redhat-linux
+
+// RUN: %clang --target=xxx-pc-freebsd -dumpmachine | FileCheck %s --check-prefix=XXX
+// XXX: xxx-pc-freebsd
+
+/// Fuchsia prefers normalization.
+// RUN: %clang --target=aarch64-fuchsia -dumpmachine | FileCheck %s --check-prefix=FUCHSIA
+// FUCHSIA: aarch64-unknown-fuchsia
Index: clang/lib/Driver/Driver.cpp
===================================================================
--- clang/lib/Driver/Driver.cpp
+++ clang/lib/Driver/Driver.cpp
@@ -1770,7 +1770,7 @@
   // don't expect inconsistencies w.r.t. that to matter in practice.
 
   if (C.getArgs().hasArg(options::OPT_dumpmachine)) {
-    llvm::outs() << C.getDefaultToolChain().getTripleString() << '\n';
+    llvm::outs() << C.getDriver().getTargetTriple() << '\n';
     return false;
   }
 


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