have configure check/add --gc-sections linker option

[musl] / configure

diff --git a/configure b/configure
index de357bc..dece1d0 100755 (executable)
--- a/configure
+++ b/configure
@@ -329,6 +329,13 @@ printf "yes\n"
 CFLAGS_C99FSE="$CFLAGS_C99FSE -D__may_alias__="
 fi
 
+#
+# The GNU toolchain defaults to assuming unmarked files need an
+# executable stack, potentially exposing vulnerabilities in programs
+# linked with such object files. Fix this.
+#
+tryflag CFLAGS_C99FSE -Wa,--noexecstack
+
 #
 # Check for options to disable stack protector, which needs to be
 # disabled for a few early-bootstrap translation units. If not found,
@@ -430,11 +437,15 @@ tryflag CFLAGS_AUTO -fno-unwind-tables
 tryflag CFLAGS_AUTO -fno-asynchronous-unwind-tables
 
 #
-# The GNU toolchain defaults to assuming unmarked files need an
-# executable stack, potentially exposing vulnerabilities in programs
-# linked with such object files. Fix this.
+# Attempt to put each function and each data object in its own
+# section. This both allows additional size optimizations at link
+# time and works around a dangerous class of compiler/assembler bugs
+# whereby relative address expressions are constant-folded by the
+# assembler even when one or more of the symbols involved is
+# replaceable. See gas pr 18561 and gcc pr 66609, 68178, etc.
 #
-tryflag CFLAGS_AUTO -Wa,--noexecstack
+tryflag CFLAGS_AUTO -ffunction-sections
+tryflag CFLAGS_AUTO -fdata-sections
 
 #
 # On x86, make sure we don't have incompatible instruction set
@@ -476,10 +487,18 @@ if test "x$visibility" = xauto ; then
 # - the -include option
 # - the attributes/pragmas used in vis.h
 # - linking code that takes the address of protected symbols
+# - gcc 3.x bug that wrongly claims declarations mismatch
 printf "checking whether global visibility preinclude works... "
-echo 'int (*fp)(void);' > "$tmpc"
-echo 'int foo(void) { }' >> "$tmpc"
-echo 'int bar(void) { fp = foo; return foo(); }' >> "$tmpc"
+cat > "$tmpc" <<EOF
+__attribute__((__visibility__("default")))
+extern struct a *const x;
+typedef struct a b;
+extern b *const x;
+b *const x;
+int (*fp)(void);
+int foo(void) { }
+int bar(void) { fp = foo; return foo(); }
+EOF
 if $CC $CFLAGS_C99FSE $CPPFLAGS $CFLAGS \
   -DSHARED -fPIC -I./src/internal -include vis.h \
   -nostdlib -shared -Wl,-Bsymbolic-functions \
@@ -496,6 +515,16 @@ CFLAGS_AUTO="$CFLAGS_AUTO -include vis.h"
 CFLAGS_AUTO="${CFLAGS_AUTO# }"
 fi
 
+# Reduce space lost to padding for alignment purposes by sorting data
+# objects according to their alignment reqirements. This approximates
+# optimal packing.
+tryldflag LDFLAGS_AUTO -Wl,--sort-section,alignment
+tryldflag LDFLAGS_AUTO -Wl,--sort-common
+
+# When linking shared library, drop dummy weak definitions that were
+# replaced by strong definitions from other translation units.
+tryldflag LDFLAGS_AUTO -Wl,--gc-sections
+
 # Some patched GCC builds have these defaults messed up...
 tryldflag LDFLAGS_AUTO -Wl,--hash-style=both
 
@@ -548,6 +577,7 @@ test "$ARCH" = "microblaze" && trycppif __MICROBLAZEEL__ "$t" \
 && SUBARCH=${SUBARCH}el
 
 if test "$ARCH" = "sh" ; then
+tryflag CFLAGS_AUTO -Wa,--isa=any
 trycppif __BIG_ENDIAN__ "$t" && SUBARCH=${SUBARCH}eb
 if trycppif "__SH_FPU_ANY__ || __SH4__" "$t" ; then
 # Some sh configurations are broken and replace double with float
@@ -620,12 +650,14 @@ libdir = $libdir
 includedir = $includedir
 syslibdir = $syslibdir
 CC = $CC
-CFLAGS = $CFLAGS_AUTO $CFLAGS
+CFLAGS = $CFLAGS
+CFLAGS_AUTO = $CFLAGS_AUTO
 CFLAGS_C99FSE = $CFLAGS_C99FSE
 CFLAGS_MEMOPS = $CFLAGS_MEMOPS
 CFLAGS_NOSSP = $CFLAGS_NOSSP
 CPPFLAGS = $CPPFLAGS
-LDFLAGS = $LDFLAGS_AUTO $LDFLAGS
+LDFLAGS = $LDFLAGS
+LDFLAGS_AUTO = $LDFLAGS_AUTO
 CROSS_COMPILE = $CROSS_COMPILE
 LIBCC = $LIBCC
 OPTIMIZE_GLOBS = $OPTIMIZE_GLOBS