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Teach IVUsers to keep things simpler and track loop-invariant strides only

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for uses inside the loop. This works better with LSR. Disabled behind
-simplify-iv-users while benchmarking.

llvm-svn: 89299
This commit is contained in:
Jim Grosbach 2009-11-19 02:05:44 +00:00
parent f5f954f888
commit 3a0e57424e
1 changed files with 10 additions and 0 deletions
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10
lib/Analysis/IVUsers.cpp
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@ -24,6 +24,7 @@
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/CommandLine.h"
#include <algorithm>
using namespace llvm;
@ -31,6 +32,10 @@ char IVUsers::ID = 0;
static RegisterPass<IVUsers>
X("iv-users", "Induction Variable Users", false, true);
static cl::opt<bool>
SimplifyIVUsers("simplify-iv-users", cl::Hidden, cl::init(false),
cl::desc("Restrict IV Users to loop-invariant strides"));
Pass *llvm::createIVUsersPass() {
return new IVUsers();
}
@ -208,6 +213,11 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I) {
if (!getSCEVStartAndStride(ISE, L, UseLoop, Start, Stride, SE, DT))
return false; // Non-reducible symbolic expression, bail out.
// Keep things simple. Don't touch loop-variant strides.
if (SimplifyIVUsers && !Stride->isLoopInvariant(L)
&& L->contains(I->getParent()))
return false;
SmallPtrSet<Instruction *, 4> UniqueUsers;
for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
UI != E; ++UI) {