diff options
Diffstat (limited to 'acinclude.m4')
| -rw-r--r-- | acinclude.m4 | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/acinclude.m4 b/acinclude.m4 index 4ca9d79fc..641f590c6 100644 --- a/acinclude.m4 +++ b/acinclude.m4 @@ -629,6 +629,25 @@ main () } ]) +# A certain _GLOBAL_OFFSET_TABLE_ problem in past versions of gas, tickled +# by recent versions of gcc. +# +if test "$gmp_prog_cc_works" = yes; then + case $host in + X86_PATTERN) + # this problem only arises in PIC code, so don't need to test when + # --disable-shared. We don't necessarily have $enable_shared set to + # yes at this point, it will still be unset for the default (which is + # yes); hence the use of "!= no". + if test "$enable_shared" != no; then + GMP_PROG_CC_X86_GOT_EAX_EMITTED([$1], + [GMP_ASM_X86_GOT_EAX_OK([$1],, + [gmp_prog_cc_works="no, bad gas GOT with eax"])]) + fi + ;; + esac +fi + AC_MSG_RESULT($gmp_prog_cc_works) case $gmp_prog_cc_works in yes) @@ -825,6 +844,57 @@ fi ]) +dnl GMP_PROG_CC_X86_GOT_EAX_EMITTED(CC+CFLAGS, [ACTION-YES] [, ACTION-NO]) +dnl ---------------------------------------------------------------------- +dnl Determine whether CC+CFLAGS emits instructions using %eax with +dnl _GLOBAL_OFFSET_TABLE_. This test is for use on x86 systems. +dnl +dnl Recent versions of gcc will use %eax for the GOT in leaf functions, for +dnl instance gcc 3.3.3 with -O3. This avoids having to save and restore +dnl %ebx which otherwise usually holds the GOT, and is what gcc used in the +dnl past. +dnl +dnl %ecx and %edx are also candidates for this sort of optimization, and +dnl are used under lesser optimization levels, like -O2 in 3.3.3. FIXME: +dnl It's not quite clear what the conditions for using %eax are, we might +dnl need more test code to provoke it. +dnl +dnl The motivation for this test is that past versions of gas have bugs +dnl affecting this usage, see GMP_ASM_X86_GOT_EAX_OK. +dnl +dnl This test is not specific to gcc, other compilers might emit %eax GOT +dnl insns like this, though we've not investigated that. +dnl +dnl This is for use by compiler probing in GMP_PROG_CC_WORKS, so we doesn't +dnl cache the result. +dnl +dnl -fPIC is hard coded here, because this test is for use before libtool +dnl has established the pic options. It's right for gcc, but perhaps not +dnl other compilers. + +AC_DEFUN([GMP_PROG_CC_X86_GOT_EAX_EMITTED], +[echo "Testing gcc GOT with eax emitted" >&AC_FD_CC +cat >conftest.c <<\EOF +[int foo; +int bar () { return foo; } +]EOF +tmp_got_emitted=no +gmp_compile="$1 -fPIC -S conftest.c >&AC_FD_CC 2>&1" +if AC_TRY_EVAL(gmp_compile); then + if grep "addl.*_GLOBAL_OFFSET_TABLE_.*eax" conftest.s >/dev/null; then + tmp_got_emitted=yes + fi +fi +rm -f conftest.* +echo "Result: $tmp_got_emitted" >&AC_FD_CC +if test "$tmp_got_emitted" = yes; then + ifelse([$2],,:,[$2]) +else + ifelse([$3],,:,[$3]) +fi +]) + + dnl GMP_HPC_HPPA_2_0(cc,[ACTION-IF-GOOD][,ACTION-IF-BAD]) dnl --------------------------------------------------------- dnl Find out whether a HP compiler is good enough to generate hppa 2.0. @@ -2163,6 +2233,122 @@ fi ]) +dnl GMP_ASM_X86_GOT_EAX_OK(CC+CFLAGS, [ACTION-YES] [, ACTION-NO]) +dnl ------------------------------------------------------------- +dnl Determine whether _GLOBAL_OFFSET_TABLE_ used with %eax is ok. +dnl +dnl An instruction +dnl +dnl addl $_GLOBAL_OFFSET_TABLE_, %eax +dnl +dnl is incorrectly assembled by gas 2.12 (or thereabouts) and earlier. It +dnl puts an addend 2 into the R_386_GOTPC relocation, but it should be 1 +dnl for this %eax form being a 1 byte opcode (with other registers it's 2 +dnl opcode bytes). See note about this in mpn/x86/README too. +dnl +dnl We assemble this, surrounded by some unlikely byte sequences as +dnl delimiters, and check for the bad output. +dnl +dnl This is for use by compiler probing in GMP_PROG_CC_WORKS, so the result +dnl is not cached. +dnl +dnl This test is not specific to gas, but old gas is the only assembler we +dnl know of with this problem. The Solaris has been seen coming out ok. +dnl +dnl ".text" is hard coded because this macro is wanted before GMP_ASM_TEXT. +dnl This should be fine, ".text" is normal on x86 systems, and certainly +dnl will be fine with the offending gas. +dnl +dnl If an error occurs when assembling, we consider the assembler ok, since +dnl the bad output does not occur. This happens for instance on mingw, +dnl where _GLOBAL_OFFSET_TABLE_ results in a bfd error, since there's no +dnl GOT etc in PE object files. +dnl +dnl This test is used before the object file extension has been determined, +dnl so we force output to conftest.o. Using -o with -c is not portable, +dnl but we think all x86 compilers will accept -o with -c, certainly gcc +dnl does. +dnl +dnl -fPIC is hard coded here, because this test is for use before libtool +dnl has established the pic options. It's right for gcc, but perhaps not +dnl other compilers. + +AC_DEFUN([GMP_ASM_X86_GOT_EAX_OK], +[echo "Testing gas GOT with eax good" >&AC_FD_CC +cat >conftest.awk <<\EOF +[BEGIN { + want[0] = "001" + want[1] = "043" + want[2] = "105" + want[3] = "147" + want[4] = "211" + want[5] = "253" + want[6] = "315" + want[7] = "357" + + want[8] = "005" + want[9] = "002" + want[10] = "000" + want[11] = "000" + want[12] = "000" + + want[13] = "376" + want[14] = "334" + want[15] = "272" + want[16] = "230" + want[17] = "166" + want[18] = "124" + want[19] = "062" + want[20] = "020" + + result = "yes" +} +{ + for (f = 2; f <= NF; f++) + { + for (i = 0; i < 20; i++) + got[i] = got[i+1]; + got[20] = $f; + + found = 1 + for (i = 0; i < 21; i++) + if (got[i] != want[i]) + { + found = 0 + break + } + if (found) + { + result = "no" + exit + } + } +} +END { + print result +} +]EOF +cat >conftest.s <<\EOF +[ .text + .byte 1, 35, 69, 103, 137, 171, 205, 239 + addl $_GLOBAL_OFFSET_TABLE_, %eax + .byte 254, 220, 186, 152, 118, 84, 50, 16 +]EOF +tmp_got_good=yes +gmp_compile="$1 -fPIC -o conftest.o -c conftest.s >&AC_FD_CC 2>&1" +if AC_TRY_EVAL(gmp_compile); then + tmp_got_good=`od -b conftest.o | $AWK -f conftest.awk` +fi +rm -f conftest.* +echo "Result: $tmp_got_good" >&AC_FD_CC +if test "$tmp_got_good" = no; then + ifelse([$3],,:,[$3]) +else + ifelse([$2],,:,[$2]) +fi +]) + + dnl GMP_ASM_X86_MMX([ACTION-IF-YES][,ACTION-IF-NO]) dnl ----------------------------------------------- dnl Determine whether the assembler supports MMX instructions. |