Fix -split-obj on Mac OS via -fasm

The problem of the splitter was that it re-emitted section directives
for every dynamic label found. The following was torn apart

.symbol_stubs
.indirect <symbol>
L_<symbol>$stub: 
	jmp *...
L_<symbol>$stub_binder:
	..somebinding code..

into

.symbol_stubs
.indirect_symbol <symbol>
L_<symbol>$stub: 
	jmp *...
.symbol_stubs <--- NEW
L_<symbol>$stub_binder:
	..somebinding code..

This is incorrect as the Mac OS assembler enforces that every new code
section that goes into .symbol_stubs is associated with the linker
directive .indirect_symbol. This sanity check is obviously violated
when we reemit .symbol_stub in the splitter. The solution is to ignore
everything that ends with $stub_binder as new label, and chuck it into
a single label for $stub.

Also the splitter has to recognize .section __DATA... for the lazy_ptr
indirection symbol. Adds a reminder to PositionIndependentCode.hs to
take care of the splitter when the code generation is changed.

This should not affect -fvia-c as the code generated by the C compiler
is entirely different.

1 files changed, 3 insertions, 0 deletions

diff --git a/compiler/nativeGen/PositionIndependentCode.hs b/compiler/nativeGen/PositionIndependentCode.hs
index 4001078df1..6a94de22b2 100644
--- a/compiler/nativeGen/PositionIndependentCode.hs
+++ b/compiler/nativeGen/PositionIndependentCode.hs
@@ -372,6 +372,9 @@ pprGotDeclaration = Pretty.empty
 -- On Darwin, we have to generate our own stub code for lazy binding..
 -- For each processor architecture, there are two versions, one for PIC
 -- and one for non-PIC.
+--
+-- Whenever you change something in this assembler output, make sure
+-- the splitter in driver/split/ghc-split.lprl recognizes the new output
 pprImportedSymbol importedLbl
 #if powerpc_TARGET_ARCH
     | Just (CodeStub, lbl) <- dynamicLinkerLabelInfo importedLbl