From 44b99a6d5f24afcd8476d0d2701e1ca4ab9b35c1 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Mon, 22 Mar 2021 12:24:26 +0100 Subject: exec: Build page-vary-common.c with -fno-lto MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In bbc17caf81f, we used an alias attribute to allow target_page to be declared const, and yet be initialized late. This fails when using LTO with several versions of gcc. The compiler looks through the alias and decides that the const variable is statically initialized to zero, then propagates that zero to many uses of the variable. This can be avoided by compiling one object file with -fno-lto. In this way, any initializer cannot be seen, and the constant propagation does not occur. Since we are certain to have this separate compilation unit, we can drop the alias attribute as well. We simply have differing declarations for target_page in different compilation units. Drop the use of init_target_page, and drop the configure detection for CONFIG_ATTRIBUTE_ALIAS. In order to change the compilation flags for a file with meson, we must use a static_library. This runs into specific_ss, where we would need to create many static_library instances. Fix this by splitting page-vary.c: the page-vary-common.c part is compiled once as a static_library, while the page-vary.c part is left in specific_ss in order to handle the target-specific value of TARGET_PAGE_BITS_MIN. Reported-by: Gavin Shan Signed-off-by: Richard Henderson Message-Id: <20210321211534.2101231-1-richard.henderson@linaro.org> [PMD: Fix typo in subject, split original patch in 3] Signed-off-by: Philippe Mathieu-Daudé Tested-by: Gavin Shan Message-Id: <20210322112427.4045204-4-f4bug@amsat.org> [rth: Update MAINTAINERS] Signed-off-by: Richard Henderson --- configure | 19 ------------------- 1 file changed, 19 deletions(-) (limited to 'configure') diff --git a/configure b/configure index 6187209..edf9dc8 100755 --- a/configure +++ b/configure @@ -4890,21 +4890,6 @@ if test "$plugins" = "yes" && fi ######################################## -# See if __attribute__((alias)) is supported. -# This false for Xcode 9, but has been remedied for Xcode 10. -# Unfortunately, travis uses Xcode 9 by default. - -attralias=no -cat > $TMPC << EOF -int x = 1; -extern const int y __attribute__((alias("x"))); -int main(void) { return 0; } -EOF -if compile_prog "" "" ; then - attralias=yes -fi - -######################################## # check if getauxval is available. getauxval=no @@ -5935,10 +5920,6 @@ if test "$atomic64" = "yes" ; then echo "CONFIG_ATOMIC64=y" >> $config_host_mak fi -if test "$attralias" = "yes" ; then - echo "CONFIG_ATTRIBUTE_ALIAS=y" >> $config_host_mak -fi - if test "$getauxval" = "yes" ; then echo "CONFIG_GETAUXVAL=y" >> $config_host_mak fi -- cgit v1.1