[llvm] [llvm-objdump] Add triple support to `mcpu=help` (PR #165661)

[James Henderson via llvm-commits]

================
@@ -14,3 +14,30 @@ FileHeader:
   Data:            ELFDATA2LSB
   Type:            ET_EXEC
   Machine:         EM_X86_64
+
+# RUN: cp %t a.out
+# RUN: llvm-objdump -d --mcpu=help 2>&1 \
+# RUN:   | FileCheck %s --check-prefix=CHECK-DEFAULT-FILE
+# RUN: rm a.out
+
+# CHECK-DEFAULT-FILE: Available CPUs for this target:
+# CHECK-DEFAULT-FILE: Available features for this target:
+
+# RUN: llvm-objdump --triple=arm --mcpu=help %t 2>&1 \
+# RUN:   | FileCheck %s --check-prefix=CHECK-TRIPLE-PRIORITY
+
+# CHECK-TRIPLE-PRIORITY: Available CPUs for this target:
+# CHECK-TRIPLE-PRIORITY: Available features for this target:
+# CHECK-TRIPLE-PRIORITY: arm
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jh7370 wrote:

I'd move just enough to test the interaction of --mcpu=help and --triple. In other words, show that when --triple is specified with --mcpu=help:
1) If there are no input files, the triple is used.
2) If there are input files, the triple is used, even if it doesn't match the first object.

https://github.com/llvm/llvm-project/pull/165661