Teach SCEVExpander to expand arithmetic involving pointers into GEP
instructions. It attempts to create high-level multi-operand GEPs,
though in cases where this isn't possible it falls back to casting
the pointer to i8* and emitting a GEP with that. Using GEP instructions
instead of ptrtoint+arithmetic+inttoptr helps pointer analyses that
don't use ScalarEvolution, such as BasicAliasAnalysis.
Also, make the AddrModeMatcher more aggressive in handling GEPs.
Previously it assumed that operand 0 of a GEP would require a register
in almost all cases. It now does extra checking and can do more
matching if operand 0 of the GEP is foldable. This fixes a problem
that was exposed by SCEVExpander using GEPs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72093 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
index 2287f20..56bb4fe 100644
--- a/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -172,7 +172,7 @@
// Expand the code for the iteration count into the preheader of the loop.
BasicBlock *Preheader = L->getLoopPreheader();
- Value *ExitCnt = Rewriter.expandCodeFor(RHS, IndVar->getType(),
+ Value *ExitCnt = Rewriter.expandCodeFor(RHS, CmpIndVar->getType(),
Preheader->getTerminator());
// Insert a new icmp_ne or icmp_eq instruction before the branch.
@@ -218,7 +218,7 @@
// Scan all of the instructions in the loop, looking at those that have
// extra-loop users and which are recurrences.
- SCEVExpander Rewriter(*SE, *LI);
+ SCEVExpander Rewriter(*SE);
// We insert the code into the preheader of the loop if the loop contains
// multiple exit blocks, or in the exit block if there is exactly one.
@@ -386,7 +386,7 @@
}
// Create a rewriter object which we'll use to transform the code with.
- SCEVExpander Rewriter(*SE, *LI);
+ SCEVExpander Rewriter(*SE);
// Now that we know the largest of of the induction variable expressions
// in this loop, insert a canonical induction variable of the largest size.
@@ -478,7 +478,7 @@
BasicBlock::iterator I = Rewriter.getInsertionPoint();
// Expand loop-invariant values in the loop preheader. They will
// be sunk to the exit block later, if possible.
- NewVal =
+ NewVal =
Rewriter.expandCodeFor(AR, LargestType,
L->getLoopPreheader()->getTerminator());
Rewriter.setInsertionPoint(I);
@@ -523,7 +523,7 @@
NewAR = SE->getAddExpr(NewAR, PromotedOffset);
// Expand the addrec into instructions.
- Value *V = Rewriter.expandCodeFor(NewAR, LargestType);
+ Value *V = Rewriter.expandCodeFor(NewAR);
// Insert an explicit cast if necessary to truncate the value
// down to the original stride type. This is done outside of
@@ -533,7 +533,7 @@
if (SE->getTypeSizeInBits(IVTy) != SE->getTypeSizeInBits(LargestType))
NewAR = SE->getTruncateExpr(NewAR, IVTy);
if (Rewriter.isInsertedExpression(NewAR))
- V = Rewriter.expandCodeFor(NewAR, IVTy);
+ V = Rewriter.expandCodeFor(NewAR);
else {
V = Rewriter.InsertCastOfTo(CastInst::getCastOpcode(V, false,
IVTy, false),
diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 0427bc1..557f34b 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -367,12 +367,14 @@
void RewriteInstructionToUseNewBase(const SCEVHandle &NewBase,
Instruction *InsertPt,
SCEVExpander &Rewriter, Loop *L, Pass *P,
+ LoopInfo &LI,
SmallVectorImpl<WeakVH> &DeadInsts);
Value *InsertCodeForBaseAtPosition(const SCEVHandle &NewBase,
const Type *Ty,
SCEVExpander &Rewriter,
- Instruction *IP, Loop *L);
+ Instruction *IP, Loop *L,
+ LoopInfo &LI);
void dump() const;
};
}
@@ -386,12 +388,12 @@
Value *BasedUser::InsertCodeForBaseAtPosition(const SCEVHandle &NewBase,
const Type *Ty,
SCEVExpander &Rewriter,
- Instruction *IP, Loop *L) {
+ Instruction *IP, Loop *L,
+ LoopInfo &LI) {
// Figure out where we *really* want to insert this code. In particular, if
// the user is inside of a loop that is nested inside of L, we really don't
// want to insert this expression before the user, we'd rather pull it out as
// many loops as possible.
- LoopInfo &LI = Rewriter.getLoopInfo();
Instruction *BaseInsertPt = IP;
// Figure out the most-nested loop that IP is in.
@@ -405,8 +407,7 @@
InsertLoop = InsertLoop->getParentLoop();
}
- Value *Base = Rewriter.expandCodeFor(NewBase, NewBase->getType(),
- BaseInsertPt);
+ Value *Base = Rewriter.expandCodeFor(NewBase, 0, BaseInsertPt);
SCEVHandle NewValSCEV = SE->getUnknown(Base);
@@ -439,6 +440,7 @@
void BasedUser::RewriteInstructionToUseNewBase(const SCEVHandle &NewBase,
Instruction *NewBasePt,
SCEVExpander &Rewriter, Loop *L, Pass *P,
+ LoopInfo &LI,
SmallVectorImpl<WeakVH> &DeadInsts) {
if (!isa<PHINode>(Inst)) {
// By default, insert code at the user instruction.
@@ -468,7 +470,7 @@
}
Value *NewVal = InsertCodeForBaseAtPosition(NewBase,
OperandValToReplace->getType(),
- Rewriter, InsertPt, L);
+ Rewriter, InsertPt, L, LI);
// Replace the use of the operand Value with the new Phi we just created.
Inst->replaceUsesOfWith(OperandValToReplace, NewVal);
@@ -527,7 +529,7 @@
PN->getIncomingBlock(i)->getTerminator() :
OldLoc->getParent()->getTerminator();
Code = InsertCodeForBaseAtPosition(NewBase, PN->getType(),
- Rewriter, InsertPt, L);
+ Rewriter, InsertPt, L, LI);
DOUT << " Changing PHI use to ";
DEBUG(WriteAsOperand(*DOUT, Code, /*PrintType=*/false));
@@ -1580,8 +1582,8 @@
<< *Stride << ":\n"
<< " Common base: " << *CommonExprs << "\n";
- SCEVExpander Rewriter(*SE, *LI);
- SCEVExpander PreheaderRewriter(*SE, *LI);
+ SCEVExpander Rewriter(*SE);
+ SCEVExpander PreheaderRewriter(*SE);
BasicBlock *Preheader = L->getLoopPreheader();
Instruction *PreInsertPt = Preheader->getTerminator();
@@ -1636,8 +1638,7 @@
// Emit the code for Base into the preheader.
Value *BaseV = 0;
if (!Base->isZero()) {
- BaseV = PreheaderRewriter.expandCodeFor(Base, Base->getType(),
- PreInsertPt);
+ BaseV = PreheaderRewriter.expandCodeFor(Base, 0, PreInsertPt);
DOUT << " INSERTING code for BASE = " << *Base << ":";
if (BaseV->hasName())
@@ -1758,7 +1759,7 @@
RewriteExpr = SE->getAddExpr(RewriteExpr, SE->getUnknown(BaseV));
User.RewriteInstructionToUseNewBase(RewriteExpr, NewBasePt,
- Rewriter, L, this,
+ Rewriter, L, this, *LI,
DeadInsts);
// Mark old value we replaced as possibly dead, so that it is eliminated
diff --git a/lib/Transforms/Utils/AddrModeMatcher.cpp b/lib/Transforms/Utils/AddrModeMatcher.cpp
index b820dd3..71049fa 100644
--- a/lib/Transforms/Utils/AddrModeMatcher.cpp
+++ b/lib/Transforms/Utils/AddrModeMatcher.cpp
@@ -255,43 +255,44 @@
// Save the valid addressing mode in case we can't match.
ExtAddrMode BackupAddrMode = AddrMode;
-
- // Check that this has no base reg yet. If so, we won't have a place to
- // put the base of the GEP (assuming it is not a null ptr).
- bool SetBaseReg = true;
- if (isa<ConstantPointerNull>(AddrInst->getOperand(0)))
- SetBaseReg = false; // null pointer base doesn't need representation.
- else if (AddrMode.HasBaseReg)
- return false; // Base register already specified, can't match GEP.
- else {
- // Otherwise, we'll use the GEP base as the BaseReg.
+ unsigned OldSize = AddrModeInsts.size();
+
+ // See if the scale and offset amount is valid for this target.
+ AddrMode.BaseOffs += ConstantOffset;
+
+ // Match the base operand of the GEP.
+ if (!MatchAddr(AddrInst->getOperand(0), Depth+1)) {
+ // If it couldn't be matched, just stuff the value in a register.
+ if (AddrMode.HasBaseReg) {
+ AddrMode = BackupAddrMode;
+ AddrModeInsts.resize(OldSize);
+ return false;
+ }
AddrMode.HasBaseReg = true;
AddrMode.BaseReg = AddrInst->getOperand(0);
}
-
- // See if the scale and offset amount is valid for this target.
- AddrMode.BaseOffs += ConstantOffset;
-
+
+ // Match the remaining variable portion of the GEP.
if (!MatchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
Depth)) {
+ // If it couldn't be matched, try stuffing the base into a register
+ // instead of matching it, and retrying the match of the scale.
AddrMode = BackupAddrMode;
- return false;
+ AddrModeInsts.resize(OldSize);
+ if (AddrMode.HasBaseReg)
+ return false;
+ AddrMode.HasBaseReg = true;
+ AddrMode.BaseReg = AddrInst->getOperand(0);
+ AddrMode.BaseOffs += ConstantOffset;
+ if (!MatchScaledValue(AddrInst->getOperand(VariableOperand),
+ VariableScale, Depth)) {
+ // If even that didn't work, bail.
+ AddrMode = BackupAddrMode;
+ AddrModeInsts.resize(OldSize);
+ return false;
+ }
}
-
- // If we have a null as the base of the GEP, folding in the constant offset
- // plus variable scale is all we can do.
- if (!SetBaseReg) return true;
-
- // If this match succeeded, we know that we can form an address with the
- // GepBase as the basereg. Match the base pointer of the GEP more
- // aggressively by zeroing out BaseReg and rematching. If the base is
- // (for example) another GEP, this allows merging in that other GEP into
- // the addressing mode we're forming.
- AddrMode.HasBaseReg = false;
- AddrMode.BaseReg = 0;
- bool Success = MatchAddr(AddrInst->getOperand(0), Depth+1);
- assert(Success && "MatchAddr should be able to fill in BaseReg!");
- Success=Success;
+
return true;
}
}