Hi Renlin,
On 12 January 2017 at 16:50, Renlin Li <renlin...@foss.arm.com> wrote: > Hi Kugan, > > some of the targets do include pie, and use the same crtbegin file as shared > object. > For example, alpha/elf.h > > And there are targets which don't do that, > For example, sh/elf.h > > Most of the elf target seem only consider the simple case. > > The purpose of this patch is to make it possible to correctly check whether > current toolchain supports shared object. > > Current dejegnu target selector "shared" tries to compile a simple source > code to with "-shared -fpic" options to check whether "-shared" is > supported. > > For arm baremetal targets with, this is not sufficient. > > arm-none-eabi is built with multilib. When running this testcase, if it's > compiled with "-march=armv7-a". > The crtbegin.o for this architecture version contains relocations which > cannot be used in shared object. > This test will fail. > > if no cpu or architecture is specified, the default cpu will be arm7tdmi. > The test will pass as crtbegin.o for this version doesn't contains any > relocations > only allowed in shared object. > > To make this "shared" target selector work for arm baremetal toolchain. The > correct way is to use different startup file for shared and non-shared > toolchain. > > If the toolchain doesn't support "-shared" option, and someone attempts to > use it > to create shared object, it will complaint that "crtbeginS.o" cannot not be > found. > I have run validations with your patch, and noticed regressions on arm-none-eabi when using default cpu or --with-cpu=cortex-m3: - PASS now FAIL [PASS => FAIL]: gcc.dg/lto/pr54709 c_lto_pr54709_0.o-c_lto_pr54709_1.o link, -fPIC -fvisibility=hidden -flto gcc.dg/lto/pr61526 c_lto_pr61526_0.o-c_lto_pr61526_1.o link, -fPIC -flto -flto-partition=1to1 gcc.dg/lto/pr64415 c_lto_pr64415_0.o-c_lto_pr64415_1.o link, -O -flto -fpic on the same configurations, I've noticed these improvements: g++.dg/ipa/devirt-28a.C -std=gnu++11 (test for excess errors) g++.dg/ipa/devirt-28a.C -std=gnu++14 (test for excess errors) g++.dg/ipa/devirt-28a.C -std=gnu++98 (test for excess errors) are now unsupported rather than fail. Why is it different when the toolchain is configured --with-cpu=cortex-a9 for instance? Are the tests involving -shared already skipped in this case? > A full history of discussion is here: > https://gcc.gnu.org/ml/gcc-patches/2016-03/msg00322.html > > > Regards, > Renlin > > > > On 12/01/17 11:47, kugan wrote: >> >> Hi, >> >> On 16/06/16 21:04, Renlin Li wrote: >>> >>> /* Now we define the strings used to build the spec file. */ >>> -#define UNKNOWN_ELF_STARTFILE_SPEC " crti%O%s crtbegin%O%s crt0%O%s" >>> +#define UNKNOWN_ELF_STARTFILE_SPEC \ >>> + "crti%O%s \ >>> + %{!shared:crtbegin%O%s} %{shared:crtbeginS%O%s} \ >>> + crt0%O%s" >> >> >> Some targets seems to use shared|pie. When you change it, shouldn't it >> also include for pie? >> >> Thanks, >> Kugan
