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-rw-r--r--llvm/include/llvm/Analysis/ScalarEvolution.h8
-rw-r--r--llvm/include/llvm/Analysis/ScalarEvolutionExpressions.h18
-rw-r--r--llvm/lib/Analysis/ScalarEvolution.cpp40
-rw-r--r--llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp13
-rw-r--r--llvm/test/Transforms/LoopStrengthReduce/pr3399.ll32
5 files changed, 102 insertions, 9 deletions
diff --git a/llvm/include/llvm/Analysis/ScalarEvolution.h b/llvm/include/llvm/Analysis/ScalarEvolution.h
index 0786b51f535..d94329d265b 100644
--- a/llvm/include/llvm/Analysis/ScalarEvolution.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolution.h
@@ -89,6 +89,10 @@ namespace llvm {
const SCEVHandle &Conc,
ScalarEvolution &SE) const = 0;
+ /// dominates - Return true if elements that makes up this SCEV dominates
+ /// the specified basic block.
+ virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const = 0;
+
/// print - Print out the internal representation of this scalar to the
/// specified stream. This should really only be used for debugging
/// purposes.
@@ -124,6 +128,10 @@ namespace llvm {
const SCEVHandle &Conc,
ScalarEvolution &SE) const;
+ virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const {
+ return true;
+ }
+
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVCouldNotCompute *S) { return true; }
static bool classof(const SCEV *S);
diff --git a/llvm/include/llvm/Analysis/ScalarEvolutionExpressions.h b/llvm/include/llvm/Analysis/ScalarEvolutionExpressions.h
index 652a99d0fca..61bb25a03b9 100644
--- a/llvm/include/llvm/Analysis/ScalarEvolutionExpressions.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolutionExpressions.h
@@ -20,6 +20,7 @@ namespace llvm {
class ConstantInt;
class ConstantRange;
class APInt;
+ class DominatorTree;
enum SCEVTypes {
// These should be ordered in terms of increasing complexity to make the
@@ -58,6 +59,10 @@ namespace llvm {
return this;
}
+ bool dominates(BasicBlock *BB, DominatorTree *DT) const {
+ return true;
+ }
+
virtual void print(std::ostream &OS) const;
void print(std::ostream *OS) const { if (OS) print(*OS); }
@@ -100,6 +105,8 @@ namespace llvm {
return SE.getTruncateExpr(H, Ty);
}
+ virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const;
+
virtual void print(std::ostream &OS) const;
void print(std::ostream *OS) const { if (OS) print(*OS); }
@@ -142,6 +149,8 @@ namespace llvm {
return SE.getZeroExtendExpr(H, Ty);
}
+ bool dominates(BasicBlock *BB, DominatorTree *DT) const;
+
virtual void print(std::ostream &OS) const;
void print(std::ostream *OS) const { if (OS) print(*OS); }
@@ -184,6 +193,8 @@ namespace llvm {
return SE.getSignExtendExpr(H, Ty);
}
+ bool dominates(BasicBlock *BB, DominatorTree *DT) const;
+
virtual void print(std::ostream &OS) const;
void print(std::ostream *OS) const { if (OS) print(*OS); }
@@ -250,6 +261,8 @@ namespace llvm {
const SCEVHandle &Conc,
ScalarEvolution &SE) const;
+ bool dominates(BasicBlock *BB, DominatorTree *DT) const;
+
virtual const char *getOperationStr() const = 0;
virtual const Type *getType() const { return getOperand(0)->getType(); }
@@ -343,6 +356,7 @@ namespace llvm {
return SE.getUDivExpr(L, R);
}
+ bool dominates(BasicBlock *BB, DominatorTree *DT) const;
virtual const Type *getType() const;
@@ -437,6 +451,8 @@ namespace llvm {
const SCEVHandle &Conc,
ScalarEvolution &SE) const;
+ bool dominates(BasicBlock *BB, DominatorTree *DT) const;
+
virtual void print(std::ostream &OS) const;
void print(std::ostream *OS) const { if (OS) print(*OS); }
@@ -518,6 +534,8 @@ namespace llvm {
return this;
}
+ bool dominates(BasicBlock *BB, DominatorTree *DT) const;
+
virtual const Type *getType() const;
virtual void print(std::ostream &OS) const;
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 59e76c0538f..4e0dba7e04b 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -66,6 +66,7 @@
#include "llvm/GlobalVariable.h"
#include "llvm/Instructions.h"
#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/Transforms/Scalar.h"
@@ -205,6 +206,10 @@ SCEVTruncateExpr::~SCEVTruncateExpr() {
SCEVTruncates->erase(std::make_pair(Op, Ty));
}
+bool SCEVTruncateExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
+ return Op->dominates(BB, DT);
+}
+
void SCEVTruncateExpr::print(std::ostream &OS) const {
OS << "(truncate " << *Op << " to " << *Ty << ")";
}
@@ -227,6 +232,10 @@ SCEVZeroExtendExpr::~SCEVZeroExtendExpr() {
SCEVZeroExtends->erase(std::make_pair(Op, Ty));
}
+bool SCEVZeroExtendExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
+ return Op->dominates(BB, DT);
+}
+
void SCEVZeroExtendExpr::print(std::ostream &OS) const {
OS << "(zeroextend " << *Op << " to " << *Ty << ")";
}
@@ -249,6 +258,10 @@ SCEVSignExtendExpr::~SCEVSignExtendExpr() {
SCEVSignExtends->erase(std::make_pair(Op, Ty));
}
+bool SCEVSignExtendExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
+ return Op->dominates(BB, DT);
+}
+
void SCEVSignExtendExpr::print(std::ostream &OS) const {
OS << "(signextend " << *Op << " to " << *Ty << ")";
}
@@ -306,6 +319,14 @@ replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
return this;
}
+bool SCEVCommutativeExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
+ for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
+ if (!getOperand(i)->dominates(BB, DT))
+ return false;
+ }
+ return true;
+}
+
// SCEVUDivs - Only allow the creation of one SCEVUDivExpr for any particular
// input. Don't use a SCEVHandle here, or else the object will never be
@@ -317,6 +338,10 @@ SCEVUDivExpr::~SCEVUDivExpr() {
SCEVUDivs->erase(std::make_pair(LHS, RHS));
}
+bool SCEVUDivExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
+ return LHS->dominates(BB, DT) && RHS->dominates(BB, DT);
+}
+
void SCEVUDivExpr::print(std::ostream &OS) const {
OS << "(" << *LHS << " /u " << *RHS << ")";
}
@@ -337,6 +362,15 @@ SCEVAddRecExpr::~SCEVAddRecExpr() {
Operands.end())));
}
+bool SCEVAddRecExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
+ for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
+ if (!getOperand(i)->dominates(BB, DT))
+ return false;
+ }
+ return true;
+}
+
+
SCEVHandle SCEVAddRecExpr::
replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
const SCEVHandle &Conc,
@@ -391,6 +425,12 @@ bool SCEVUnknown::isLoopInvariant(const Loop *L) const {
return true;
}
+bool SCEVUnknown::dominates(BasicBlock *BB, DominatorTree *DT) const {
+ if (Instruction *I = dyn_cast<Instruction>(getValue()))
+ return DT->dominates(I->getParent(), BB);
+ return true;
+}
+
const Type *SCEVUnknown::getType() const {
return V->getType();
}
diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 055114c215d..0945a5759f8 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -438,16 +438,11 @@ static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L,
Start = SE->getAddExpr(Start, AddRec->getOperand(0));
if (!isa<SCEVConstant>(AddRec->getOperand(1))) {
- // If stride is an instruction, make sure it dominates the loop header.
+ // If stride is an instruction, make sure it dominates the loop preheader.
// Otherwise we could end up with a use before def situation.
- if (SCEVUnknown *SU = dyn_cast<SCEVUnknown>(AddRec->getOperand(1))) {
- if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) {
- BasicBlock *StrideBB = I->getParent();
- BasicBlock *Preheader = L->getLoopPreheader();
- if (!DT->dominates(StrideBB, Preheader))
- return false;
- }
- }
+ BasicBlock *Preheader = L->getLoopPreheader();
+ if (!AddRec->getOperand(1)->dominates(Preheader, DT))
+ return false;
DOUT << "[" << L->getHeader()->getName()
<< "] Variable stride: " << *AddRec << "\n";
diff --git a/llvm/test/Transforms/LoopStrengthReduce/pr3399.ll b/llvm/test/Transforms/LoopStrengthReduce/pr3399.ll
new file mode 100644
index 00000000000..9d2f5eda1b3
--- /dev/null
+++ b/llvm/test/Transforms/LoopStrengthReduce/pr3399.ll
@@ -0,0 +1,32 @@
+; RUN: llvm-as < %s | opt -loop-reduce | llvm-dis
+; PR3399
+
+@g_53 = external global i32 ; <i32*> [#uses=1]
+
+define i32 @foo() nounwind {
+bb5.thread:
+ br label %bb
+
+bb: ; preds = %bb5, %bb5.thread
+ %indvar = phi i32 [ 0, %bb5.thread ], [ %indvar.next, %bb5 ] ; <i32> [#uses=2]
+ br i1 false, label %bb5, label %bb1
+
+bb1: ; preds = %bb
+ %l_2.0.reg2mem.0 = sub i32 0, %indvar ; <i32> [#uses=1]
+ %0 = volatile load i32* @g_53, align 4 ; <i32> [#uses=1]
+ %1 = trunc i32 %l_2.0.reg2mem.0 to i16 ; <i16> [#uses=1]
+ %2 = trunc i32 %0 to i16 ; <i16> [#uses=1]
+ %3 = mul i16 %2, %1 ; <i16> [#uses=1]
+ %4 = icmp eq i16 %3, 0 ; <i1> [#uses=1]
+ br i1 %4, label %bb7, label %bb2
+
+bb2: ; preds = %bb2, %bb1
+ br label %bb2
+
+bb5: ; preds = %bb
+ %indvar.next = add i32 %indvar, 1 ; <i32> [#uses=1]
+ br label %bb
+
+bb7: ; preds = %bb1
+ ret i32 1
+}
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