[llvm-libtool-darwin] Add support for -arch_only

Add support for -arch_only option for llvm-libtool-darwin. This diff
also adds support for accepting universal files as input and flattening
them to create the required static library. Supports input universal
files contaning both Mach-O object files or archives.

Differences from cctools' libtool:
- `-arch_only` can be specified multiple times
- archives containing universal files are considered invalid (libtool
allows such archives)

Reviewed by jhenderson, smeenai

Differential Revision: https://reviews.llvm.org/D84770

Author: sammy-1234

llvm/docs/CommandGuide/llvm-libtool-darwin.rst

@@ -21,45 +21,50 @@ OPTIONS
 --------
 :program:`llvm-libtool-darwin` supports the following options:
 
-.. option:: -h, -help
-
-  Show help and usage for this command.
+.. option:: -arch_only <architecture>
 
-.. option:: -help-list
-
-  Show help and usage for this command without grouping the options
-  into categories.
+  Build a static library only for the specified `<architecture>` and ignore all
+  other architectures in the files.
 
 .. option:: -color
 
   Use colors in output.
 
-.. option:: -version
+.. option:: -D
 
-  Display the version of this program.
+  Use zero for timestamps and UIDs/GIDs. This is set by default.
 
-.. option:: -D
+.. option:: -filelist <listfile[,dirname]>
 
- Use zero for timestamps and UIDs/GIDs. This is set by default.
+  Read input file names from `<listfile>`. File names are specified in `<listfile>`
+  one per line, separated only by newlines. Whitespace on a line is assumed
+  to be part of the filename. If the directory name, `dirname`, is also
+  specified then it is prepended to each file name in the `<listfile>`.
 
-.. option:: -U
+.. option:: -h, -help
+
+  Show help and usage for this command.
 
- Use actual timestamps and UIDs/GIDs.
+.. option:: -help-list
+
+  Show help and usage for this command without grouping the options
+  into categories.
 
 .. option:: -o <filename>
 
   Specify the output file name. Must be specified exactly once.
 
 .. option:: -static
 
- Produces a static library from the input files.
+  Produces a static library from the input files.
 
-.. option:: -filelist <listfile[,dirname]>
+.. option:: -U
+
+  Use actual timestamps and UIDs/GIDs.
 
- Read input file names from `<listfile>`. File names are specified in `<listfile>`
- one per line, separated only by newlines. Whitespace on a line is assumed
- to be part of the filename. If the directory name, `dirname`, is also
- specified then it is prepended to each file name in the `<listfile>`.
+.. option:: -version
+
+  Display the version of this program.
 
 EXIT STATUS
 -----------

llvm/test/tools/llvm-libtool-darwin/cpu-subtype-matching.test

@@ -0,0 +1,269 @@
+## This test checks that the CPU subtype matching logic is handled correctly.
+
+# RUN: yaml2obj %s --docnum=1 -o %t.armv6
+# RUN: yaml2obj %s --docnum=2 -o %t.armv7
+
+# RUN: llvm-libtool-darwin -static -o %t.lib %t.armv6 %t.armv7 -arch_only armv7
+
+## Check that only armv7 binary is present:
+# RUN: llvm-ar t %t.lib | \
+# RUN:   FileCheck %s --check-prefix=ARM-NAMES --implicit-check-not={{.}} -DPREFIX=%basename_t.tmp
+
+# ARM-NAMES: [[PREFIX]].armv7
+
+## Check that only armv7 symbol is present:
+# RUN: llvm-nm --print-armap %t.lib | \
+# RUN:   FileCheck %s --check-prefix=ARM-SYMBOLS -DPREFIX=%basename_t.tmp --match-full-lines
+
+# ARM-SYMBOLS:      Archive map
+# ARM-SYMBOLS-NEXT: _armv7 in [[PREFIX]].armv7
+# ARM-SYMBOLS-EMPTY:
+
+## armv6.yaml
+## CPUTYPE:    CPU_TYPE_ARM
+## CPUSUBTYPE: CPU_SUBTYPE_ARM_V6
+--- !mach-o
+FileHeader:
+  magic:           0xFEEDFACE
+  cputype:         0x0000000C
+  cpusubtype:      0x00000006
+  filetype:        0x00000001
+  ncmds:           2
+  sizeofcmds:      148
+  flags:           0x00002000
+LoadCommands:
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+    vmaddr:          0
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+        reserved2:       0x00000000
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+    - ''
+    - _armv6
+    - ''
+...
+
+## armv7.yaml
+## CPUTYPE:    CPU_TYPE_ARM
+## CPUSUBTYPE: CPU_SUBTYPE_ARM_V7
+--- !mach-o
+FileHeader:
+  magic:           0xFEEDFACE
+  cputype:         0x0000000C
+  cpusubtype:      0x00000009
+  filetype:        0x00000001
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+    - ''
+    - _armv7
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+...
+
+# RUN: yaml2obj %s --docnum=3 -o %t.x86_64
+# RUN: yaml2obj %s --docnum=4 -o %t.x86_64_h
+
+# RUN: llvm-libtool-darwin -static -o %t.lib %t.x86_64 %t.x86_64_h -arch_only x86_64
+
+## Check that only x86_64 binary is present:
+# RUN: llvm-ar t %t.lib | \
+# RUN:   FileCheck %s --check-prefix=X86-NAMES --implicit-check-not={{.}} -DPREFIX=%basename_t.tmp
+
+# X86-NAMES: [[PREFIX]].x86_64
+
+## Check that only x86_64 symbol is present:
+# RUN: llvm-nm --print-armap %t.lib | \
+# RUN:   FileCheck %s --check-prefix=X86-SYMBOLS -DPREFIX=%basename_t.tmp --match-full-lines
+
+# X86-SYMBOLS:      Archive map
+# X86-SYMBOLS-NEXT: _x86_64 in [[PREFIX]].x86_64
+# X86-SYMBOLS-EMPTY:
+
+## x86_64.yaml
+## CPUTYPE:    CPU_TYPE_X86_64
+## CPUSUBTYPE: CPU_SUBTYPE_X86_64_ALL
+--- !mach-o
+FileHeader:
+  magic:           0xFEEDFACF
+  cputype:         0x01000007
+  cpusubtype:      0x00000003
+  filetype:        0x00000001
+  ncmds:           2
+  sizeofcmds:      176
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+    - _x86_64
+    - ''
+...
+
+## x86_64h.yaml
+## CPUTYPE:    CPU_TYPE_X86_64
+## CPUSUBTYPE: CPU_SUBTYPE_X86_64_H
+--- !mach-o
+FileHeader:
+  magic:           0xFEEDFACF
+  cputype:         0x01000007
+  cpusubtype:      0x00000008
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+    - ''
+    - _x86_64_h
+    - ''
+...