Bug#1085966: ghc: ftbfs: help: Use extra --ghc-options does not reduce binary size (based on ghc 9.6.6-2)

[fanpeng]

On Thu, 24 Oct 2024 11:16:04 +0800 zhangdandan wrote:

I'm aware of the problem.

For LoongArch64, support in ghc-9.6-* is not complete. Maybe we should 
finish it.
To put it simply, we should add some code like this:
----
41c41
< rewrites = [rewriteSymType, rewriteAVX, rewriteCall]
---
 > rewrites = [rewriteSymType, rewriteAVX, rewriteCall, rewriteJump]
123a124,146
 >         appendInsn i = (`B.append` B.pack ("\n\t" ++ i))
 >
 > -- | This rewrites bl and b jump inst to avoid creating PLT entries for
 > -- functions on loongarch64, because there is no separate call 
instruction
 > -- for function calls in loongarch64. Also, this replacement will load
 > -- the function address from the GOT, which is resolved to point to the
 > -- real address of the function.
 > rewriteJump :: Rewrite
 > rewriteJump platform l
 >   | not isLoongArch64 = Nothing
 >   | isBL l            = Just $ replaceJump "bl" "$ra" "$ra" l
 >   | isB l             = Just $ replaceJump "b" "$zero" "$t0" l
 >   | otherwise         = Nothing
 >   where
 >     isLoongArch64 = platformArch platform == ArchLoongArch64
 >     isBL = B.isPrefixOf (B.pack "bl\t")
 >     isB = B.isPrefixOf (B.pack "b\t")
 >
 >     replaceJump jump rd rj l =
 >         appendInsn ("jirl" ++ "\t" ++ rd ++ ", " ++ rj ++ ", 0") $ 
removeBracket $
 >         replaceOnce (B.pack (jump ++ "\t%plt(")) (B.pack ("la\t" ++ 
rj ++ ", ")) l
 >       where
 >         removeBracket = replaceOnce (B.pack ")") (B.pack "")
----
This will replace the jump insns with the wider's insns. Otherwise, for 
building some
Larger packages, such as haskell-pandoc, cause the previous error:
R_LARCH_B26 overflow.


 > Package: ghc
 > Version: 9.6.6-2
 > Severity: important
 > Tags: ftbfs help
 > User: debian-loongarch at lists.debian.org
 > Usertags: loong64
 >
 > Hi Ilias and LocutusOfBorg,
 >
 > Based on ghc 9.6.6-2(use extra --ghc-options does not reduce binary
 > size), compiling haskell-pandoc still throws errors.
 > 1. extra --ghc-options in d/rules is as follows,
 > ```
 > ifneq (,$(filter loong64, $(DEB_HOST_ARCH)))
 >   EXTRA_HADRIAN_FLAGS += "*.*.ghc.*.opts += -optc-mcmodel=medium"
 > endif
 >
 > ```
 >
 > 2. error log of haskell-pandoc is as follows,
 > ```
 > Building test suite 'test-pandoc' for pandoc-3.1.11.1..
 > [58 of 58] Linking dist-ghc/build/test-pandoc/test-pandoc
 > /usr/bin/ld: dist-ghc/build/test-pandoc/test-pandoc-tmp/Tests/Helpers.o:
 > relocation R_LARCH_B26 overflow 0x89f8bbc
 > Dump relocate record:
 > stack top        relocation name        symbol
 > ......
 > dist-ghc/build/test-pandoc/test-pandoc-tmp/Tests/Helpers.o:(.text+0x4):
 > relocation truncated to fit: R_LARCH_B26 against symbol `stg_ap_0_fast'
 > defined in .text section in
 > 
/usr/lib/ghc/lib/../lib/loongarch64-linux-ghc-9.6.6/rts-1.0.2/libHSrts-1.0.2_thr.a(Apply.thr_o)
 > /usr/bin/ld: final link failed: bad value
 > collect2: error: ld returned 1 exit status
 > ghc-9.6.6: `loongarch64-linux-gnu-gcc' failed in phase `Linker'. (Exit
 > code: 1)
 > -e: error: debian/hlibrary.setup build --builddir=dist-ghc returned exit
 > code 1
 > ......
 >
 > ```
 >
 > For ghc, the full build log can be found at
 > https://buildd.debian.org/status/logs.php?pkg=ghc&arch=loong64.
 > For haskell-pandoc, the full build log can be found at
 > 
https://buildd.debian.org/status/logs.php?pkg=haskell-pandoc&arch=loong64.
 >
 > Please give us some suggestions.
 > Let's discuss and solve the problem together under this bug.
 > Your opinions are welcome.
 >
 > Dandan
 >
 >
 >

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