a place more useful. In particular, if we can put them in a place where code
will be able to fall into it, do so. Otherwise, put it in a place it can fall
through into a successor. Otherwise, if preventing a fallthrough, move to the
end of the function, out of the way.
This deletes several hundred unconditional branches from spass.
llvm-svn: 31149
1. Remove a bunch of ifdef'd code.
2. When a block just contains an uncond branch, change all blocks branching
to it to jump to the destination instead.
3. If branch analysis tells us some edges in the machinecfg are not actually
possible, remove them.
#2 triggers a suprisingly large number of times.
llvm-svn: 31094
branch folding can now compile stuff like this:
void foo(int W, int X, int Y, int Z) {
if (W & 1) {
for (; X;--X) bar();
} else if (W & 2) {
for (; Y;--Y) bar();
} else if (W & 4) {
for (; Z;--Z) bar();
} else if (W & 8) {
for (; W;--W) bar();
}
if (W) {
bar();
}
}
contrived testcase where loops exits all end up merging together. To have
the loop merges be:
...
cmplw cr0, r30, r27
bne cr0, LBB1_14 ;bb38
LBB1_16: ;cond_next48.loopexit
mr r27, r29
LBB1_20: ;cond_next48
cmplwi cr0, r27, 0
beq cr0, LBB1_22 ;UnifiedReturnBlock
...
instead of:
...
cmplw cr0, r30, r27
bne cr0, LBB1_14 ;bb38
LBB1_16: ;cond_next48.loopexit
mr r27, r29
b LBB1_20 ;cond_next48
LBB1_17: ;cond_next48.loopexit1
b LBB1_20 ;cond_next48
LBB1_18: ;cond_next48.loopexit2
b LBB1_20 ;cond_next48
LBB1_19: ;cond_next48.loopexit3
LBB1_20: ;cond_next48
cmplwi cr0, r27, 0
beq cr0, LBB1_22 ;UnifiedReturnBlock
...
This is CodeGen/PowerPC/branch-opt.ll
llvm-svn: 31006
Move include/Config and include/Support into include/llvm/Config,
include/llvm/ADT and include/llvm/Support. From here on out, all LLVM
public header files must be under include/llvm/.
llvm-svn: 16137
Chris Lattner