UNIQUE_BITS is not crosscompiler-friendly

Things break when I try to build crosscompiler from 32-bit system to 64-bit system. For example i386-linux -> powerpc64-linux:

$ ./configure --target=powerpc64-unknown-linux-gnu --with-system-libffi --with-libffi-includes=/usr/lib/libffi-3.2.1/include/
$ make

"inplace/bin/ghc-stage1" -static  -H32m -O -optc-I/usr/lib/libffi-3.2.1/include -Wall   -Iincludes -Iincludes/dist -Iincludes/dist-derivedconstants/header -Iincludes/dist-ghcconstants/header 
-Irts -Irts/dist/build -DCOMPILING_RTS -this-unit-id rts -dcmm-lint      -i -irts -irts/dist/build -Irts/dist/build -irts/dist/build/./autogen -Irts/dist/build/./autogen           -O2    -Wno
ncanonical-monad-instances  -c rts/StgStartup.cmm -o rts/dist/build/StgStartup.o
/tmp/ghc19687_0/ghc_4.s: Assembler messages:

/tmp/ghc19687_0/ghc_4.s:11:0: error:
     Error: unknown pseudo-op: `.l'
   |
11 | .L�4:
   | ^

The problem here comes from definition of UNIQUE_BITS:

# cat compiler/Unique.h 
#include "../includes/MachDeps.h"

#define UNIQUE_BITS (WORD_SIZE_IN_BITS - 8)

Here WORD_SIZE_IN_BITS is a target platform size (64) while stage1 is still running on host platform (32).

As a result uniques truncate down to zero:

compiler/basicTypes/Unique.hs:    tag  = ord c `shiftL` UNIQUE_BITS
compiler/basicTypes/Unique.hs:        tag = chr (u `shiftR` UNIQUE_BITS)

As we operate on host Ints we could use the following:

#define UNIQUE_BITS sizeof(HsInt) * 8 -- C code

#define UNIQUE_BITS (finiteBitSize (undefined :: Int) * 8) -- Haskell code

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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