sparsec: use a compatible exception model on cygwin

On the cygwin platform, some of the backend tests fail due to the 'llc'
tool using win32 'structured exception' assembler directives, which the
platform assembler 'as' does not accept:

  $ make check
  ...
       TEST    'hello, world' code generation (backend/hello.c)
  error: actual error text does not match expected error text.
  error: see backend/hello.c.error.* for further investigation.
  --- backend/hello.c.error.expected	2018-06-03 17:14:30.550972400 +0100
  +++ backend/hello.c.error.got	2018-06-03 17:14:30.478731900 +0100
  @@ -0,0 +1,6 @@
  +{standard input}: Assembler messages:
  +{standard input}:14: Error: invalid register for .seh_pushreg
  +{standard input}:14: Error: junk at end of line, first unrecognized character is `5'
  +{standard input}:20: Error: invalid register for .seh_setframe
  +{standard input}:20: Error: missing separator
  +mv: cannot stat '/tmp/tmp.oTA6mS.o': No such file or directory
  ...
  Out of 288 tests, 275 passed, 13 failed (10 of them are known to fail)
  make: *** [Makefile:236: check] Error 1
  $

The exception model used by 'llc' can be changed from the command line
to be one of 'default', 'dwarf', 'sjlj', 'arm' or 'wineh'. In this case
the default is 'wineh' (windows exception handling). The 'sjlj' model is
the older (setjmp,longjmp) stack-based model, which is no longer used on
Linux. The newer 'dwarf' model uses a 'zero cost' table based method.
(The 'arm' model is not relevant here). For more information, see [1].

After some experiments, using small test programs compiled with gcc and
g++, comparing the output of tools like 'nm' and 'objdump', it seems
that cygwin binutils are employing the 'sjlj' model. (Using the 'dwarf'
model on 'llc' also works on simple programs).

In order to fix the test failures, add an '-exception-model=sjlj' option
to the 'llc' invocation when executing sparsec on the cygwin platform.

[1] http://www.hexblog.com/wp-content/uploads/2012/06/Recon-2012-Skochinsky-Compiler-Internals.pdf

Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/sparsec b/sparsec
index 6c609901..bafe2da5 100755
--- a/sparsec
+++ b/sparsec
@@ -34,7 +34,17 @@ TMPFILE=`mktemp -t tmp.XXXXXX`
 
 LLC=`"${LLVM_CONFIG:-llvm-config}" --bindir`/llc
 
-$DIRNAME/sparse-llvm $SPARSEOPTS | $LLC | as -o $TMPFILE
+LLC_ARCH_OPTS=
+case "$(uname -s)" in
+*CYGWIN*)
+	# cygwin uses the sjlj (setjmp-longjmp) exception model
+	LLC_ARCH_OPTS="-exception-model=sjlj"
+	;;
+*)
+	;;
+esac
+
+$DIRNAME/sparse-llvm $SPARSEOPTS | $LLC ${LLC_ARCH_OPTS} | as -o $TMPFILE
 
 if [ $NEED_LINK -eq 1 ]; then
 	if [ -z $OUTFILE ]; then