[glibc] Run check-installed-headers concurrently for each header

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=19e158b7f052d03262d2aaeb4e5b5df022797cb0

commit 19e158b7f052d03262d2aaeb4e5b5df022797cb0
Author: Adhemerval Zanella <[email protected]>
Date:   Wed Jun 10 18:45:39 2026 -0300

    Run check-installed-headers concurrently for each header
    
    The check-installed-headers-c/-cxx tests ran one script invocation per
    subdirectory over all of its installed headers, performing about 80
    compiler invocations per header serially.
    
    Give each header its own intermediate target so the compiler
    invocations parallelize under the make jobserver, recording the
    per-header script exit status next to the output.  The .out target
    concatenates the per-header outputs in the original $(headers) order
    and fails if any recorded status is non-zero, so both the .out contents
    (verified byte-identical for all 76 files) and the tests.sum results
    are unchanged.
    
    Results on a x86_64 machine [1] from a make check with run-built-tests=no
    show neutral results, and on aarch64 machine [2] it improves from 241.574s
    to 182.405.
    
    [1] Ryzen 5900x, 12c/24t, gcc 16.1.1, binutils 2.26, and GNU make 4.3
    [2] N1, 80c, gcc 15.1.1, binutils 2.25, GNU make 4.3
    
    Reviewed-by: Sam James <[email protected]>

Diff:
---
 Makefile | 37 ++++++++++++++++++++++++++-----------
 Rules    | 38 +++++++++++++++++++++++++++-----------
 2 files changed, 53 insertions(+), 22 deletions(-)

diff --git a/Makefile b/Makefile
index 23f3c1895d..b421dbbafb 100644
--- a/Makefile
+++ b/Makefile
@@ -684,26 +684,41 @@ $(objpfx)check-local-headers.out: scripts/check-local-headers.sh
 	$(evaluate-test)
 
 ifneq "$(headers)" ""
-# Special test of all the installed headers in this directory.
+# Special test of all the installed headers in this directory.  See
+# Rules for the per-header split rationale.
 tests-special += $(objpfx)check-installed-headers-c.out
 libof-check-installed-headers-c := testsuite
-$(objpfx)check-installed-headers-c.out: \
++cih-c-iouts := $(patsubst %,$(objpfx)check-installed-headers-c/%.iout,\
+			   $(headers))
+$(+cih-c-iouts): $(objpfx)check-installed-headers-c/%.iout: \
     scripts/check-installed-headers.sh $(headers)
-	$(SHELL) $(..)scripts/check-installed-headers.sh c $(supported-fortify) \
-	  "$(CC) $(test-config-cflags-finput-charset-ascii) \
-	     $(filter-out -std=%,$(CFLAGS)) -D_ISOMAC $(+includes)" \
-	  $(headers) > $@; \
+	$(make-target-directory)
+	($(SHELL) $(..)scripts/check-installed-headers.sh c $(supported-fortify) \
+	   "$(CC) $(test-config-cflags-finput-charset-ascii) \
+	      $(filter-out -std=%,$(CFLAGS)) -D_ISOMAC $(+includes)" \
+	   $*; echo $$? > $@-ret) > $@T; \
+	mv -f $@T $@
+$(objpfx)check-installed-headers-c.out: $(+cih-c-iouts)
+	cat $^ > $@; \
+	! grep -qv '^0$$' $(+cih-c-iouts:%=%-ret); \
 	$(evaluate-test)
 
 ifneq "$(CXX)" ""
 tests-special += $(objpfx)check-installed-headers-cxx.out
 libof-check-installed-headers-cxx := testsuite
-$(objpfx)check-installed-headers-cxx.out: \
++cih-cxx-iouts := $(patsubst %,$(objpfx)check-installed-headers-cxx/%.iout,\
+			     $(headers))
+$(+cih-cxx-iouts): $(objpfx)check-installed-headers-cxx/%.iout: \
     scripts/check-installed-headers.sh $(headers)
-	$(SHELL) $(..)scripts/check-installed-headers.sh c++ $(supported-fortify) \
-	  "$(CXX) $(test-config-cxxflags-finput-charset-ascii) \
-	     $(filter-out -std=%,$(CXXFLAGS)) -D_ISOMAC $(+includes)" \
-	  $(headers) > $@; \
+	$(make-target-directory)
+	($(SHELL) $(..)scripts/check-installed-headers.sh c++ $(supported-fortify) \
+	   "$(CXX) $(test-config-cxxflags-finput-charset-ascii) \
+	      $(filter-out -std=%,$(CXXFLAGS)) -D_ISOMAC $(+includes)" \
+	   $*; echo $$? > $@-ret) > $@T; \
+	mv -f $@T $@
+$(objpfx)check-installed-headers-cxx.out: $(+cih-cxx-iouts)
+	cat $^ > $@; \
+	! grep -qv '^0$$' $(+cih-cxx-iouts:%=%-ret); \
 	$(evaluate-test)
 endif # $(CXX)
 
diff --git a/Rules b/Rules
index 385246f07d..a74043e605 100644
--- a/Rules
+++ b/Rules
@@ -80,15 +80,24 @@ common-generated += dummy.o dummy.c
 
 ifneq "$(headers)" ""
 # Test that all of the headers installed by this directory can be compiled
-# in isolation.
+# in isolation.  Each header gets its own intermediate target so that the
+# it can run concurrently under -j; the .out target concatenates the per-header
+# results in the original $(headers) order.
 tests-special += $(objpfx)check-installed-headers-c.out
 libof-check-installed-headers-c := testsuite
-$(objpfx)check-installed-headers-c.out: \
++cih-c-iouts := $(patsubst %,$(objpfx)check-installed-headers-c/%.iout,\
+			   $(headers))
+$(+cih-c-iouts): $(objpfx)check-installed-headers-c/%.iout: \
     $(..)scripts/check-installed-headers.sh $(headers)
-	$(SHELL) $(..)scripts/check-installed-headers.sh c $(supported-fortify) \
-	  "$(CC) $(test-config-cflags-finput-charset-ascii) \
-	     $(filter-out -std=%,$(CFLAGS)) -D_ISOMAC $(+includes)" \
-	  $(headers) > $@; \
+	$(make-target-directory)
+	($(SHELL) $(..)scripts/check-installed-headers.sh c $(supported-fortify) \
+	   "$(CC) $(test-config-cflags-finput-charset-ascii) \
+	      $(filter-out -std=%,$(CFLAGS)) -D_ISOMAC $(+includes)" \
+	   $*; echo $$? > $@-ret) > $@T; \
+	mv -f $@T $@
+$(objpfx)check-installed-headers-c.out: $(+cih-c-iouts)
+	cat $^ > $@; \
+	! grep -qv '^0$$' $(+cih-c-iouts:%=%-ret); \
 	$(evaluate-test)
 
 ifneq "$(CXX)" ""
@@ -96,12 +105,19 @@ ifneq "$(CXX)" ""
 # in isolation as C++.
 tests-special += $(objpfx)check-installed-headers-cxx.out
 libof-check-installed-headers-cxx := testsuite
-$(objpfx)check-installed-headers-cxx.out: \
++cih-cxx-iouts := $(patsubst %,$(objpfx)check-installed-headers-cxx/%.iout,\
+			     $(headers))
+$(+cih-cxx-iouts): $(objpfx)check-installed-headers-cxx/%.iout: \
     $(..)scripts/check-installed-headers.sh $(headers)
-	$(SHELL) $(..)scripts/check-installed-headers.sh c++ $(supported-fortify) \
-	  "$(CXX) $(test-config-cxxflags-finput-charset-ascii) \
-	     $(filter-out -std=%,$(CXXFLAGS)) -D_ISOMAC $(+includes)" \
-	  $(headers) > $@; \
+	$(make-target-directory)
+	($(SHELL) $(..)scripts/check-installed-headers.sh c++ $(supported-fortify) \
+	   "$(CXX) $(test-config-cxxflags-finput-charset-ascii) \
+	      $(filter-out -std=%,$(CXXFLAGS)) -D_ISOMAC $(+includes)" \
+	   $*; echo $$? > $@-ret) > $@T; \
+	mv -f $@T $@
+$(objpfx)check-installed-headers-cxx.out: $(+cih-cxx-iouts)
+	cat $^ > $@; \
+	! grep -qv '^0$$' $(+cih-cxx-iouts:%=%-ret); \
 	$(evaluate-test)
 endif # $(CXX)