properly fix mpfr to restore clang usage

[howarth@…]

The breakage in mpfr with the Xcode 4.2.0 release was mishandled in macports. The actual cause of the breakage was due to a clang bug which was exposed in when tis support was enabled in clang in the Xcode 4.2.0 release. The mpfr 3.1.0 release tickles this bug because it supports tis if present in the compiler. The possible fixes for this problem is either to require Xcode 4.2.1 or later which has this tis code generation bug fixed,

radr://10291355, "Xcode 4.2 miscompiles tls support in MPFR 3.1.0"

by back porting the fix from llvm.org (r142553) for the same issue...

​http://llvm.org/bugs/show_bug.cgi?id=11111

The attached Portfile.diff fixes this issue as we have in fink by passing --disable-thread-safe to configure. This has no impact on the build with non-clang compilers as none of them have ever supported tis code generation. For clang, it restores the previous build behavior prior to Xcode 4.2.0 where tis support wasn't available.

Testing on x86_64-apple-darwin11 with Xcode 4.3 shows...

/usr/bin/make  check-TESTS
[tversion] GMP: header 5.0.4, library 5.0.4
[tversion] MPFR tuning parameters from src/x86_64/core2/mparam.h
PASS: tversion
PASS: tinternals
PASS: tinits
PASS: tisqrt
PASS: tsgn
PASS: tcheck
PASS: tisnan
PASS: texceptions
PASS: tset_exp
PASS: tset
PASS: mpf_compat
PASS: mpfr_compat
PASS: reuse
PASS: tabs
PASS: tacos
PASS: tacosh
PASS: tadd
PASS: tadd1sp
PASS: tadd_d
PASS: tadd_ui
PASS: tagm
PASS: tai
PASS: tasin
PASS: tasinh
PASS: tatan
PASS: tatanh
PASS: taway
PASS: tbuildopt
PASS: tcan_round
PASS: tcbrt
PASS: tcmp
PASS: tcmp2
PASS: tcmp_d
PASS: tcmp_ld
PASS: tcmp_ui
PASS: tcmpabs
PASS: tcomparisons
PASS: tconst_catalan
PASS: tconst_euler
PASS: tconst_log2
PASS: tconst_pi
PASS: tcopysign
PASS: tcos
PASS: tcosh
PASS: tcot
PASS: tcoth
PASS: tcsc
PASS: tcsch
PASS: td_div
PASS: td_sub
PASS: tdigamma
PASS: tdim
PASS: tdiv
PASS: tdiv_d
PASS: tdiv_ui
PASS: teint
PASS: teq
PASS: terf
PASS: texp
PASS: texp10
PASS: texp2
PASS: texpm1
PASS: tfactorial
PASS: tfits
PASS: tfma
PASS: tfmod
PASS: tfms
PASS: tfprintf
PASS: tfrac
PASS: tfrexp
PASS: tgamma
PASS: tget_flt
PASS: tget_d
PASS: tget_d_2exp
PASS: tget_f
PASS: tget_ld_2exp
SKIP: tget_set_d64
PASS: tget_sj
PASS: tget_str
PASS: tget_z
PASS: tgmpop
PASS: tgrandom
PASS: thyperbolic
PASS: thypot
PASS: tinp_str
PASS: tj0
PASS: tj1
PASS: tjn
PASS: tl2b
PASS: tlgamma
PASS: tli2
PASS: tlngamma
PASS: tlog
PASS: tlog10
PASS: tlog1p
PASS: tlog2
PASS: tmin_prec
PASS: tminmax
PASS: tmodf
PASS: tmul
PASS: tmul_2exp
PASS: tmul_d
PASS: tmul_ui
PASS: tnext
PASS: tout_str
PASS: toutimpl
PASS: tpow
PASS: tpow3
PASS: tpow_all
PASS: tpow_z
PASS: tprintf
PASS: trandom
PASS: trec_sqrt
PASS: tremquo
PASS: trint
PASS: troot
PASS: tround_prec
PASS: tsec
PASS: tsech
PASS: tset_d
PASS: tset_f
PASS: tset_ld
PASS: tset_q
PASS: tset_si
PASS: tset_sj
PASS: tset_str
PASS: tset_z
PASS: tset_z_exp
PASS: tsi_op
PASS: tsin
PASS: tsin_cos
PASS: tsinh
PASS: tsinh_cosh
PASS: tsprintf
PASS: tsqr
PASS: tsqrt
PASS: tsqrt_ui
PASS: tstckintc
PASS: tstdint
PASS: tstrtofr
PASS: tsub
PASS: tsub1sp
PASS: tsub_d
PASS: tsub_ui
PASS: tsubnormal
PASS: tsum
PASS: tswap
PASS: ttan
PASS: ttanh
PASS: ttrunc
PASS: tui_div
PASS: tui_pow
PASS: tui_sub
PASS: turandom
PASS: tvalist
PASS: ty0
PASS: ty1
PASS: tyn
PASS: tzeta
PASS: tzeta_ui
[tversion] GMP: header 5.0.4, library 5.0.4
[tversion] MPFR tuning parameters from src/x86_64/core2/mparam.h
PASS: tversion
====================
All 160 tests passed
(1 test was not run)
====================
Making check in tune

[howarth@…]

Portfile.diff with better fix for Xcode 4.2.0 clang code generation issue in mpfr

[howarth@…]

An alternative fix would be to prevent mpfr from building if Xcode 4.2.0 was installed as it is the only Xcode release with this clang bug,

[neverpanic (Clemens Lang)]

Please use WikiFormatting and don't set the Milestone field.

[neverpanic (Clemens Lang)]

Have you verified gcc44, gcc45, and gcc46 build fine on Lion with this patch applied? I'm hesitating to revert r86599, which is a confirmed fix for a nasty and hard-to-debug problem (see #31604), especially since compiling with clang doesn't give us much of an advantage at the moment (although I agree we should always use the default compiler, if possible).

[howarth@…]

I have verified that the gcc45 and gcc46 builds work (gcc44 was already built). IMHO this isn't rocket science. The macports mpfr maintainer should have focused on the fact that mpfr built with clang from Xcode 4.2.0 failed its test suite. This is how the tls code generation bug in clang 3.0svn of Xcode 4.2.0 was detected, fixed in llvm.org's clang 3.0 and then back ported into Xcode 4.2.1's clang. We have been using the --disable-thread-safe approach to workaround the the Xcode 4.2.0 clang bug in fink for four months now without issues in gcc4x build. Again this issue is unique to Xcode 4.2.0 because it both introduced the tis support for clang on Lion and thus exposed the latent tis code generation bug in clang. FYI, I am the fink maintainer for their gcc packages.

[howarth@…]

Just to be clear, the FSF gcc bootstrap problems seen with mpfr using clang from Xcode 4.2.0 are just a manifestation of the broken mpfr that it builds using the newly available tis support in clang for Lion. The focus should have been entirely on mpfr's test suite failures with clang from Xcode 4.2 in the absence of the--disable-thread-safe configure flag being use. It may have confused you that this issue 'disappeared' (i.e. was fixed) in Xcode 4.2.1 and later so that the tls support was usable in mpfr. Again an alternative fix is to have the Portfile refuse to build on Xcode 4.2.0.

[howarth@…]

Note that the last option isn't feasible as Xcode 4.2.1 doesn't exist for Snow Leopard (but the bug doesn't exist there because there is no tls kernel support in darwin10 for clang to use). So simply using --disable-thread-safe in mpfr is the cleanest approach. IMHO, the new tls clang support is somewhat experimental as there isn't a lot of code that detects its. The mpfr package was one of the few to do so.

[howarth@…]

FYI, this is the commit fixing the clang bug...

142550 | evancheng | 2011-10-19 15:22:54 -0700 (Wed, 19 Oct 2011) | 1 line

Fix TLS lowering bug. The CopyFromReg must be glued to the TLSCALL. rdar://10291355

[neverpanic (Clemens Lang)]

Replying to howarth@…:

The macports mpfr maintainer should have focused on the fact that mpfr built with clang from Xcode 4.2.0 failed its test suite.

That might not have happened due to the fact, that there currently is no maintainer for mpfr in macports.

Commited in r90220. Thanks for the patch and the explanations.