perf python: Fix splitting CC into compiler and options

Noticed this build failure on archlinux:base when building with clang:

  clang-14: error: optimization flag '-ffat-lto-objects' is not supported [-Werror,-Wignored-optimization-argument]

In tools/perf/util/setup.py we check if clang supports that option, but
since commit 3cad53a ("perf python: Account for multiple words
in CC") this got broken as in the common case where CC="clang":

  >>> cc="clang"
  >>> print(cc.split()[0])
  clang
  >>> option="-ffat-lto-objects"
  >>> print(str(cc.split()[1:]) + option)
  []-ffat-lto-objects
  >>>

And then the Popen will call clang with that bogus option name that in
turn will not produce the b"unknown argument" or b"is not supported"
that this function uses to detect if the option is not available and
thus later on clang will be called with an unknown/unsupported option.

Fix it by looking if really there are options in the provided CC
variable, and if so override 'cc' with the first token and append the
options to the 'option' variable.

Fixes: 3cad53a ("perf python: Account for multiple words in CC")
Cc: Adrian Hunter <[email protected]>
Cc: Fangrui Song <[email protected]>
Cc: Florian Fainelli <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: John Keeping <[email protected]>
Cc: Khem Raj <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Michael Petlan <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Sedat Dilek <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: acmel

tools/perf/util/setup.py

@@ -3,11 +3,20 @@
 from re import sub
 
 cc = getenv("CC")
-cc_is_clang = b"clang version" in Popen([cc.split()[0], "-v"], stderr=PIPE).stderr.readline()
+
+# Check if CC has options, as is the case in yocto, where it uses CC="cc --sysroot..."
+cc_tokens = cc.split()
+if len(cc_tokens) > 1:
+    cc = cc_tokens[0]
+    cc_options = " ".join([str(e) for e in cc_tokens[1:]]) + " "
+else:
+    cc_options = ""
+
+cc_is_clang = b"clang version" in Popen([cc, "-v"], stderr=PIPE).stderr.readline()
 src_feature_tests  = getenv('srctree') + '/tools/build/feature'
 
 def clang_has_option(option):
-    cc_output = Popen([cc.split()[0], str(cc.split()[1:]) + option, path.join(src_feature_tests, "test-hello.c") ], stderr=PIPE).stderr.readlines()
+    cc_output = Popen([cc, cc_options + option, path.join(src_feature_tests, "test-hello.c") ], stderr=PIPE).stderr.readlines()
     return [o for o in cc_output if ((b"unknown argument" in o) or (b"is not supported" in o))] == [ ]
 
 if cc_is_clang: