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Remove dead blocks in the end.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@63880 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel 2009-02-05 19:59:42 +00:00
parent 1851db6b0f
commit 39c873e38f
2 changed files with 15 additions and 3 deletions
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17
lib/Transforms/Scalar/CondPropagate.cpp
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@ -23,6 +23,7 @@
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Streams.h"
using namespace llvm;
@ -44,6 +45,7 @@ namespace {
private:
bool MadeChange;
SmallVector<BasicBlock *, 4> DeadBlocks;
void SimplifyBlock(BasicBlock *BB);
void SimplifyPredecessors(BranchInst *BI);
void SimplifyPredecessors(SwitchInst *SI);
@ -60,14 +62,22 @@ FunctionPass *llvm::createCondPropagationPass() {
bool CondProp::runOnFunction(Function &F) {
bool EverMadeChange = false;
DeadBlocks.clear();
// While we are simplifying blocks, keep iterating.
do {
MadeChange = false;
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
SimplifyBlock(BB);
for (Function::iterator BB = F.begin(), E = F.end(); BB != E;)
SimplifyBlock(BB++);
EverMadeChange = EverMadeChange || MadeChange;
} while (MadeChange);
if (EverMadeChange) {
while (!DeadBlocks.empty()) {
BasicBlock *BB = DeadBlocks.back(); DeadBlocks.pop_back();
DeleteDeadBlock(BB);
}
}
return EverMadeChange;
}
@ -111,8 +121,9 @@ void CondProp::SimplifyBlock(BasicBlock *BB) {
// Succ is now dead, but we cannot delete it without potentially
// invalidating iterators elsewhere. Just insert an unreachable
// instruction in it.
// instruction in it and delete this block later on.
new UnreachableInst(Succ);
DeadBlocks.push_back(Succ);
MadeChange = true;
}
}

1
test/Transforms/CondProp/basictest.ll
View File

@ -1,5 +1,6 @@
; RUN: llvm-as < %s | opt -condprop | llvm-dis | \
; RUN: not grep {br label}
; RUN: llvm-as < %s | opt -condprop | llvm-dis | not grep T2
define i32 @test(i1 %C) {