[Haskell-cafe] Is this a known problem?

ok ok at cs.otago.ac.nz
Thu Oct 4 18:04:06 EDT 2007

UltraSPARC II, Solaris 2.10, gcc 4.0.4 (gccfss),
Haskell GHC 6.6.1 binary release.

Trying to compile a simple file gives me oodles of errors because
ghc is generating something that makes gcc generate lots of these:

	sethi %hi(<<some register>>),<<another register>>

For people unfamiliar with SPARC assembly code, the %hi(...) operation
returns the top bits of a *literal* address, it makes absolutely no
sense to give it a register.

I have tried this version of gccfss with lots of C code and have been
unable to make it generate this construction; it's only ghc's .hc files
that do it.

Running gcc by hand on the .hc file produces 8 warnings
...lib/ghc-6.6.1/include/Regs.h: ###: warning:
   call-clobbered register used for global register variable
-DNO_GLOBAL_REG_DECLS eliminated that.

Comparing the .s file produced using 'ghc -S' with the .s file
produced by gcc'ing the .hc produced some illumination:

	.section	".text",#slloc,#execinstr,#progbits
	.align  4
#if GHC
	.align 4
	save	%sp,-96,%sp
#if GHC
	sethi	%hi(%l1),%i2
	add	%i2,%lo(%l1),%i5
	ld	[%i2+%lo(%l1)],%i2
	ld	[%i2],%l7
	lduh	[%l7-2],%l6
	sethi	%hi(MainCapability),%i5
	add	%i5,%lo(MainCapability),%i2
	ld	[%i2+8],%i5
	ld	[%i5],%i4
	lduh	[%i4-2],%i3

What with one thing and another, I'm not really sure that it's
gcc's fault.

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