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If converter was being too cute. It look for root BBs (which don't have

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successors) and use inverse depth first search to traverse the BBs. However
that doesn't work when the CFG has infinite loops. Simply do a linear
traversal of all BBs work just fine.

rdar://9344645


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130324 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2011-04-27 19:32:43 +00:00
parent bddc1ca18a
commit 309db7c947
2 changed files with 62 additions and 18 deletions
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21
lib/CodeGen/IfConversion.cpp
View File

@ -27,7 +27,6 @@
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
@ -146,10 +145,6 @@ namespace {
: BBI(b), Kind(k), NeedSubsumption(s), NumDups(d), NumDups2(d2) {}
};
/// Roots - Basic blocks that do not have successors. These are the starting
/// points of Graph traversal.
std::vector<MachineBasicBlock*> Roots;
/// BBAnalysis - Results of if-conversion feasibility analysis indexed by
/// basic block number.
std::vector<BBInfo> BBAnalysis;
@ -287,11 +282,6 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
MF.RenumberBlocks();
BBAnalysis.resize(MF.getNumBlockIDs());
// Look for root nodes, i.e. blocks without successors.
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
if (I->succ_empty())
Roots.push_back(I);
std::vector<IfcvtToken*> Tokens;
MadeChange = false;
unsigned NumIfCvts = NumSimple + NumSimpleFalse + NumTriangle +
@ -406,7 +396,6 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
}
Tokens.clear();
Roots.clear();
BBAnalysis.clear();
if (MadeChange && IfCvtBranchFold) {
@ -924,13 +913,9 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB,
/// candidates.
void IfConverter::AnalyzeBlocks(MachineFunction &MF,
std::vector<IfcvtToken*> &Tokens) {
std::set<MachineBasicBlock*> Visited;
for (unsigned i = 0, e = Roots.size(); i != e; ++i) {
for (idf_ext_iterator<MachineBasicBlock*> I=idf_ext_begin(Roots[i],Visited),
E = idf_ext_end(Roots[i], Visited); I != E; ++I) {
MachineBasicBlock *BB = *I;
AnalyzeBlock(BB, Tokens);
}
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
MachineBasicBlock *BB = I;
AnalyzeBlock(BB, Tokens);
}
// Sort to favor more complex ifcvt scheme.

59
test/CodeGen/ARM/2011-04-27-IfCvtBug.ll Normal file
View File

@ -0,0 +1,59 @@
; RUN: llc < %s -mtriple=thumbv7-apple-ios
; If converter was being too cute. It look for root BBs (which don't have
; successors) and use inverse depth first search to traverse the BBs. However
; that doesn't work when the CFG has infinite loops. Simply do a linear
; traversal of all BBs work just fine.
; rdar://9344645
%struct.hc = type { i32, i32, i32, i32 }
define i32 @t(i32 %type) optsize {
entry:
br i1 undef, label %if.then, label %if.else
if.then:
unreachable
if.else:
br i1 undef, label %if.then15, label %if.else18
if.then15:
unreachable
if.else18:
switch i32 %type, label %if.else173 [
i32 3, label %if.then115
i32 1, label %if.then102
]
if.then102:
br i1 undef, label %cond.true10.i, label %t.exit
cond.true10.i:
br label %t.exit
t.exit:
unreachable
if.then115:
br i1 undef, label %if.else163, label %if.else145
if.else145:
%call150 = call fastcc %struct.hc* @foo(%struct.hc* undef, i32 34865152) optsize
br label %while.body172
if.else163:
%call168 = call fastcc %struct.hc* @foo(%struct.hc* undef, i32 34078720) optsize
br label %while.body172
while.body172:
br label %while.body172
if.else173:
ret i32 -1
}
declare hidden fastcc %struct.hc* @foo(%struct.hc* nocapture, i32) nounwind optsize