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

[James Henderson via llvm-commits]

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@@ -0,0 +1,33 @@
+# RUN: yaml2obj %s -o %t
+# REQUIRES: arm-registered-target,x86-registered-target
+
+## Check if we can handle without -d
+# RUN: llvm-objdump --mcpu=help %t 2>&1 \
+# RUN:   | FileCheck %s --check-prefixes=CHECK-HELP,CHECK-ARM
+
+## Check if we can handle without file
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jh7370 wrote:

I thought I was pretty clear about this before. There should be a test case that shows --mcpu=help when there is no input file and no --triple or other dump options that we report an error (input file is missing, so we can't infer the triple value for printing the help). This test case should be in the pre-existing test file that isn't about --triple.

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