Throttle back tail duplication to avoid creating really ugly sequences of code.
For Transforms/TailDup/if-tail-dup.ll, f.e., it produces:
_foo:
movl 8(%esp), %eax
movl 4(%esp), %ecx
testl $1, %ecx
je LBB1_2 #cond_next
LBB1_1: #cond_true
movl $1, (%eax)
LBB1_2: #cond_next
testl $2, %ecx
je LBB1_4 #cond_next10
LBB1_3: #cond_true6
movl $1, 4(%eax)
LBB1_4: #cond_next10
testl $4, %ecx
je LBB1_6 #cond_next18
LBB1_5: #cond_true14
movl $1, 8(%eax)
LBB1_6: #cond_next18
testl $8, %ecx
je LBB1_8 #return
LBB1_7: #cond_true22
movl $1, 12(%eax)
ret
LBB1_8: #return
ret
instead of:
_foo:
movl 4(%esp), %eax
testl $2, %eax
sete %cl
movl 8(%esp), %edx
testl $1, %eax
je LBB1_2 #cond_next
LBB1_1: #cond_true
movl $1, (%edx)
testb %cl, %cl
jne LBB1_4 #cond_next10
jmp LBB1_3 #cond_true6
LBB1_2: #cond_next
testb %cl, %cl
jne LBB1_4 #cond_next10
LBB1_3: #cond_true6
movl $1, 4(%edx)
testl $4, %eax
je LBB1_6 #cond_next18
jmp LBB1_5 #cond_true14
LBB1_4: #cond_next10
testl $4, %eax
je LBB1_6 #cond_next18
LBB1_5: #cond_true14
movl $1, 8(%edx)
testl $8, %eax
je LBB1_8 #return
jmp LBB1_7 #cond_true22
LBB1_6: #cond_next18
testl $8, %eax
je LBB1_8 #return
LBB1_7: #cond_true22
movl $1, 12(%edx)
ret
LBB1_8: #return
ret
llvm-svn: 30158