From 50545f5aa0111c1e7f8917348490907d1a1e1f9b Mon Sep 17 00:00:00 2001 From: "Paul E. Murphy" Date: Fri, 7 Feb 2020 14:08:23 -0600 Subject: powerpc64le: raise GCC requirement to 7.4 for long double transition Add compiler feature tests to ensure we can build ieee128 long double. These test for -mabi=ieeelongdouble, -mno-gnu-attribute, and -Wno-psabi. Likewise, verify some compiler bugs have been addressed. These aren't helpful for building glibc, but may cause test failures when testing the new long double. See notes below from Raji. On powerpc64le, some older compiler versions give error for the function signbit() for 128-bit floating point types. This is fixed by PR83862 in gcc 8.0 and backported to gcc6 and gcc7. This patch adds a test to check compiler version to avoid compiler errors during make check. Likewise, test for -mno-gnu-attribute support which was On powerpc64le, a few files are built on IEEE long double mode (-mabi=ieeelongdouble), whereas most are built on IBM long double mode (-mabi=ibmlongdouble, the default for -mlong-double-128). Since binutils 2.31, linking object files with different long double modes causes errors similar to: ld: libc_pic.a(s_isinfl.os) uses IBM long double, libc_pic.a(ieee128-qefgcvt.os) uses IEEE long double. collect2: error: ld returned 1 exit status make[2]: *** [../Makerules:649: libc_pic.os] Error 1 The warnings are fair and correct, but in order for glibc to have support for both long double modes on powerpc64le, they have to be ignored. This can be accomplished with the use of -mno-gnu-attribute option when building the few files that require IEEE long double mode. However, -mno-gnu-attribute is not available in GCC 6, the minimum version required to build glibc, so this patch adds a test for this feature in powerpc64le builds, and fails early if it's not available. Co-Authored-By: Rajalakshmi Srinivasaraghavan Co-Authored-By: Gabriel F. T. Gomes Reviewed-by: Tulio Magno Quites Machado Filho --- INSTALL | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'INSTALL') diff --git a/INSTALL b/INSTALL index 242cb06..2fa7a81 100644 --- a/INSTALL +++ b/INSTALL @@ -467,6 +467,12 @@ build the GNU C Library: better code. As of release time, GCC 9.2.1 is the newest compiler verified to work to build the GNU C Library. + For PowerPC 64-bits little-endian (powerpc64le), a GCC version with + support for '-mno-gnu-attribute', '-mabi=ieeelongdouble', and + '-mabi=ibmlondouble' is required. These additional features are + required for building the GNU C Library with support for IEEE long + double. + For multi-arch support it is recommended to use a GCC which has been built with support for GNU indirect functions. This ensures that correct debugging information is generated for functions -- cgit v1.1