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Fix SCEVEXpander to handle arbitrary phi expansion. Includes two

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related bug fixes and corresponding assertions for uninitialized data
and missing NULL check. Test cases will be included with the new LFTR.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135333 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2011-07-16 00:59:39 +00:00
parent 4201ecae92
commit d152d03a47
2 changed files with 20 additions and 9 deletions
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4
include/llvm/Analysis/ScalarEvolutionExpander.h
View File

@ -72,8 +72,8 @@ namespace llvm {
public:
/// SCEVExpander - Construct a SCEVExpander in "canonical" mode.
explicit SCEVExpander(ScalarEvolution &se, const char *name)
: SE(se), IVName(name), IVIncInsertLoop(0), CanonicalMode(true),
Builder(se.getContext(), TargetFolder(se.TD)) {}
: SE(se), IVName(name), IVIncInsertLoop(0), IVIncInsertPos(0),
CanonicalMode(true), Builder(se.getContext(), TargetFolder(se.TD)) {}
/// clear - Erase the contents of the InsertedExpressions map so that users
/// trying to expand the same expression into multiple BasicBlocks or

25
lib/Analysis/ScalarEvolutionExpander.cpp
View File

@ -19,6 +19,7 @@
#include "llvm/LLVMContext.h"
#include "llvm/Target/TargetData.h"
#include "llvm/ADT/STLExtras.h"
using namespace llvm;
/// ReuseOrCreateCast - Arrange for there to be a cast of V to Ty at IP,
@ -848,6 +849,8 @@ SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
const Loop *L,
const Type *ExpandTy,
const Type *IntTy) {
assert(!IVIncInsertLoop || IVIncInsertPos && "Uninitialized insert position");
// Reuse a previously-inserted PHI, if present.
for (BasicBlock::iterator I = L->getHeader()->begin();
PHINode *PN = dyn_cast<PHINode>(I); ++I)
@ -872,13 +875,15 @@ SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
// If any of the operands don't dominate the insert position, bail.
// Addrec operands are always loop-invariant, so this can only happen
// if there are instructions which haven't been hoisted.
for (User::op_iterator OI = IncV->op_begin()+1,
OE = IncV->op_end(); OI != OE; ++OI)
if (Instruction *OInst = dyn_cast<Instruction>(OI))
if (!SE.DT->dominates(OInst, IVIncInsertPos)) {
IncV = 0;
break;
}
if (L == IVIncInsertLoop) {
for (User::op_iterator OI = IncV->op_begin()+1,
OE = IncV->op_end(); OI != OE; ++OI)
if (Instruction *OInst = dyn_cast<Instruction>(OI))
if (!SE.DT->dominates(OInst, IVIncInsertPos)) {
IncV = 0;
break;
}
}
if (!IncV)
break;
// Advance to the next instruction.
@ -920,6 +925,12 @@ SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
Value *StartV = expandCodeFor(Normalized->getStart(), ExpandTy,
L->getHeader()->begin());
// StartV must be hoisted into L's preheader to dominate the new phi.
Instruction *StartI = dyn_cast<Instruction>(StartV);
assert(!StartI || SE.DT->properlyDominates(StartI->getParent(),
L->getHeader()) && "");
(void)StartI;
// Expand code for the step value. Insert instructions right before the
// terminator corresponding to the back-edge. Do this before creating the PHI
// so that PHI reuse code doesn't see an incomplete PHI. If the stride is