[LLVMdev] BranchInst problem

[Vladimir Prus]

Chris Lattner wrote:

> > > I'm not sure either.  Can you send the code before and after register
> > > allocation?
> >
> > Attached.
>
> Okay, yeah the spill code looks right.  The local allocator can't keep
> virtual registers in physical registers across basic blocks.  As such, the
> vregs are spilled at the end of the entry block and then reloaded in the
> blocks they are used.

Oh, I now understand why you say default allocator is not very efficient.
> > Ehm.... I get this:
> >
> > llc: LiveIntervals.cpp:166: virtual bool
> > llvm::LiveIntervals::runOnMachineFunction(llvm::MachineFunction&):
> > Assertion `r2iit != r2iMap_.end()' failed.
>
> Hrm, that's obviously really bad. Can you send me (offline) the output of
> llc with the -debug option set and with this code before the assert:
>
>   std::cerr << "MI: " << i << " " << reg << "  "; mii->dump();
>
> Also note that it looks like your tree is a bit out of date.  You might
> try updating and see if it helps the problem.

I've updated and rebuild. The bug is still there and the output you've asked 
for is attached.

HTH,
Volodya
-------------- next part --------------
Instruction: 	%tmp.9 = shl int %tmp.8, ubyte 1		; <int> [#uses=1]
Machine Function
********** REWRITING TWO-ADDR INSTRS **********
********** Function: _Z3addii
********** COMPUTING LIVE INTERVALS **********
********** Function: _Z3addii
entry:
0	%reg1024 = load <fi#-1>
		register: %reg1024 +[20,22) +[32,34) +[2,20)
4	%reg1025 = load <fi#-2>
		register: %reg1025 +[20,22) +[32,34) +[6,20)
8	setcc %reg1024, %reg1025
12	goto %disp(label then)
16	goto %disp(label else)
then:
20	%reg1026 = + %reg1025, %reg1024
		register: %reg1026 +[22,26)
24	%gr7 = move %reg1026
		register: gr7 dead +[26,27)
28	return
else:
32	%reg1027 = + %reg1025, %reg1024
		register: %reg1027 +[34,35)
36	%gr7 = move %reg1028
		register: gr7 dead +[38,39)
40	return
********** JOINING INTERVALS ***********
entry:
0	%reg1024 = load <fi#-1>
4	%reg1025 = load <fi#-2>
8	setcc %reg1024, %reg1025
12	goto %disp(label then)
16	goto %disp(label else)
then:
20	%reg1026 = + %reg1025, %reg1024
24	%gr7 = move %reg1026
28	return
else:
32	%reg1027 = + %reg1025, %reg1024
36	%gr7 = move %reg1028
40	return
MI: 0 1024    %reg1024 = load <fi#-1>
MI: 0 1025    %reg1025 = load <fi#-2>
MI: 0 1024    setcc %reg1024, %reg1025
MI: 1 1025    setcc %reg1024, %reg1025
MI: 0 1026    %reg1026 = + %reg1025, %reg1024
MI: 1 1025    %reg1026 = + %reg1025, %reg1024
MI: 2 1024    %reg1026 = + %reg1025, %reg1024
MI: 1 1026    %gr7 = move %reg1026
MI: 0 1027    %reg1027 = + %reg1025, %reg1024
MI: 1 1025    %reg1027 = + %reg1025, %reg1024
MI: 2 1024    %reg1027 = + %reg1025, %reg1024
MI: 1 1028    %gr7 = move %reg1028
llc: LiveIntervals.cpp:161: virtual bool llvm::LiveIntervals::runOnMachineFunction(llvm::MachineFunction&): Assertion `r2iit != r2iMap_.end()' failed.
Code after instruction selection
# Machine code for _Z3addii():
  <fi #-2> is 4 bytes fixed at location [SP-20]
  <fi #-1> is 4 bytes fixed at location [SP-16]

entry (0x86b5128):
	%reg1024 = load <fi#-1>
	%reg1025 = load <fi#-2>
	setcc %reg1024, %reg1025
	goto %disp(label then)
	goto %disp(label else)

then (0x86b5358):
	%reg1026 = + %reg1025, %reg1024
	%gr7 = move %reg1026
	return

else (0x86b52b0):
	%reg1027 = + %reg1025, %reg1024
	%gr7 = move %reg1028
	return

# End machine code for _Z3addii().

llc[0x85670a6]
llc[0x85672c6]
[0xffffe420]