blob: a1bc38b642b7876bd1fac310e3c6dd520d33973d (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
|
#include "slang-ir-simplify-cfg.h"
#include "slang-ir-insts.h"
#include "slang-ir.h"
namespace Slang
{
bool processFunc(IRGlobalValueWithCode* func)
{
auto firstBlock = func->getFirstBlock();
if (!firstBlock)
return false;
SharedIRBuilder sharedBuilder(func->getModule());
IRBuilder builder(&sharedBuilder);
bool changed = false;
List<IRBlock*> workList;
HashSet<IRBlock*> processedBlock;
workList.add(func->getFirstBlock());
while (workList.getCount())
{
auto block = workList.getFirst();
workList.fastRemoveAt(0);
while (block)
{
if (auto loop = as<IRLoop>(block->getTerminator()))
{
// If continue block is unreachable, remove it.
auto continueBlock = loop->getContinueBlock();
if (continueBlock && !continueBlock->hasMoreThanOneUse())
{
loop->continueBlock.set(loop->getTargetBlock());
continueBlock->removeAndDeallocate();
}
// If there isn't any actual back jumps into loop target, remove the header
// and turn it into a normal branch.
auto targetBlock = loop->getTargetBlock();
if (targetBlock->getPredecessors().getCount() == 1 && *targetBlock->getPredecessors().begin() == block)
{
builder.setInsertBefore(loop);
List<IRInst*> args;
for (UInt i = 0; i < loop->getArgCount(); i++)
{
args.add(loop->getArg(i));
}
builder.emitBranch(targetBlock, args.getCount(), args.getBuffer());
loop->removeAndDeallocate();
}
}
// If `block` does not end with an unconditional branch, bail.
if (block->getTerminator()->getOp() != kIROp_unconditionalBranch)
break;
auto branch = as<IRUnconditionalBranch>(block->getTerminator());
auto successor = branch->getTargetBlock();
// Only perform the merge if `block` is the only predecessor of `successor`.
// We also need to make sure not to merge a block that serves as the
// merge point in CFG. Such blocks will have more than one use.
if (successor->hasMoreThanOneUse())
break;
if (block->hasMoreThanOneUse())
break;
changed = true;
Index paramIndex = 0;
auto inst = successor->getFirstDecorationOrChild();
while (inst)
{
auto next = inst->getNextInst();
if (inst->getOp() == kIROp_Param)
{
inst->replaceUsesWith(branch->getArg(paramIndex));
paramIndex++;
}
else
{
inst->removeFromParent();
inst->insertAtEnd(block);
}
inst = next;
}
branch->removeAndDeallocate();
assert(!successor->hasUses());
successor->removeAndDeallocate();
}
for (auto successor : block->getSuccessors())
{
if (processedBlock.Add(successor))
{
workList.add(successor);
}
}
}
return changed;
}
bool simplifyCFG(IRModule* module)
{
bool changed = false;
for (auto inst : module->getGlobalInsts())
{
if (auto func = as<IRFunc>(inst))
{
changed |= processFunc(func);
}
}
return changed;
}
bool simplifyCFG(IRGlobalValueWithCode* func)
{
return processFunc(func);
}
} // namespace Slang
|
