xref: /csrg-svn/old/pcc/c2.tahoe/NOTES.2 (revision 44027)
1*44027SbosticThis bug bears some striking similarities to the previous one...
2*44027Sbostic
3*44027SbosticSample code:
4*44027Sbostic
5*44027Sbostic	std	r0		# these three instructions get deleted
6*44027Sbostic	movl	4(r12),r2	# here too, but shouldn't
7*44027Sbostic	ldd	r0		# here too
8*44027Sbostic	test
9*44027Sbostic	jump
10*44027Sbostic	use of r2
11*44027Sbosticlabel:
12*44027Sbostic	instruction that kills r0
13*44027Sbostic
14*44027SbosticIf the movl is reordered above the std, it won't be deleted; if
15*44027Sbosticreordered below the ldd, it's still zapped.  If the test is 'tstl
16*44027Sbosticr12', it can get deleted too...  It doesn't seem to matter very
17*44027Sbosticmuch what the jump or use of r2 are, provided the jump is a relational
18*44027Sbosticone, of course.
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