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-rw-r--r--llvm/lib/Analysis/ConstantFolding.cpp36
-rw-r--r--llvm/lib/IR/Constants.cpp28
-rw-r--r--llvm/lib/Transforms/IPO/GlobalDCE.cpp13
3 files changed, 52 insertions, 25 deletions
diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index 09d7608c51d..b5286e8f29d 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -17,6 +17,7 @@
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/Analysis/ValueTracking.h"
@@ -880,19 +881,20 @@ Constant *llvm::ConstantFoldInstruction(Instruction *I,
return ConstantFoldInstOperands(I->getOpcode(), I->getType(), Ops, TD, TLI);
}
-/// ConstantFoldConstantExpression - Attempt to fold the constant expression
-/// using the specified DataLayout. If successful, the constant result is
-/// result is returned, if not, null is returned.
-Constant *llvm::ConstantFoldConstantExpression(const ConstantExpr *CE,
- const DataLayout *TD,
- const TargetLibraryInfo *TLI) {
- SmallVector<Constant*, 8> Ops;
- for (User::const_op_iterator i = CE->op_begin(), e = CE->op_end();
- i != e; ++i) {
+static Constant *
+ConstantFoldConstantExpressionImpl(const ConstantExpr *CE, const DataLayout *TD,
+ const TargetLibraryInfo *TLI,
+ SmallPtrSet<ConstantExpr *, 4> &FoldedOps) {
+ SmallVector<Constant *, 8> Ops;
+ for (User::const_op_iterator i = CE->op_begin(), e = CE->op_end(); i != e;
+ ++i) {
Constant *NewC = cast<Constant>(*i);
- // Recursively fold the ConstantExpr's operands.
- if (ConstantExpr *NewCE = dyn_cast<ConstantExpr>(NewC))
- NewC = ConstantFoldConstantExpression(NewCE, TD, TLI);
+ // Recursively fold the ConstantExpr's operands. If we have already folded
+ // a ConstantExpr, we don't have to process it again.
+ if (ConstantExpr *NewCE = dyn_cast<ConstantExpr>(NewC)) {
+ if (FoldedOps.insert(NewCE))
+ NewC = ConstantFoldConstantExpressionImpl(NewCE, TD, TLI, FoldedOps);
+ }
Ops.push_back(NewC);
}
@@ -902,6 +904,16 @@ Constant *llvm::ConstantFoldConstantExpression(const ConstantExpr *CE,
return ConstantFoldInstOperands(CE->getOpcode(), CE->getType(), Ops, TD, TLI);
}
+/// ConstantFoldConstantExpression - Attempt to fold the constant expression
+/// using the specified DataLayout. If successful, the constant result is
+/// result is returned, if not, null is returned.
+Constant *llvm::ConstantFoldConstantExpression(const ConstantExpr *CE,
+ const DataLayout *TD,
+ const TargetLibraryInfo *TLI) {
+ SmallPtrSet<ConstantExpr *, 4> FoldedOps;
+ return ConstantFoldConstantExpressionImpl(CE, TD, TLI, FoldedOps);
+}
+
/// ConstantFoldInstOperands - Attempt to constant fold an instruction with the
/// specified opcode and operands. If successful, the constant result is
/// returned, if not, null is returned. Note that this function can fail when
diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index 1abb6564355..2c6971c83e7 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -237,18 +237,21 @@ void Constant::destroyConstantImpl() {
delete this;
}
-/// canTrap - Return true if evaluation of this constant could trap. This is
-/// true for things like constant expressions that could divide by zero.
-bool Constant::canTrap() const {
- assert(getType()->isFirstClassType() && "Cannot evaluate aggregate vals!");
+static bool canTrapImpl(const Constant *C,
+ SmallPtrSet<const ConstantExpr *, 4> &NonTrappingOps) {
+ assert(C->getType()->isFirstClassType() && "Cannot evaluate aggregate vals!");
// The only thing that could possibly trap are constant exprs.
- const ConstantExpr *CE = dyn_cast<ConstantExpr>(this);
- if (!CE) return false;
+ const ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
+ if (!CE)
+ return false;
// ConstantExpr traps if any operands can trap.
- for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
- if (CE->getOperand(i)->canTrap())
- return true;
+ for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i) {
+ if (ConstantExpr *Op = dyn_cast<ConstantExpr>(CE->getOperand(i))) {
+ if (NonTrappingOps.insert(Op) && canTrapImpl(Op, NonTrappingOps))
+ return true;
+ }
+ }
// Otherwise, only specific operations can trap.
switch (CE->getOpcode()) {
@@ -267,6 +270,13 @@ bool Constant::canTrap() const {
}
}
+/// canTrap - Return true if evaluation of this constant could trap. This is
+/// true for things like constant expressions that could divide by zero.
+bool Constant::canTrap() const {
+ SmallPtrSet<const ConstantExpr *, 4> NonTrappingOps;
+ return canTrapImpl(this, NonTrappingOps);
+}
+
/// isThreadDependent - Return true if the value can vary between threads.
bool Constant::isThreadDependent() const {
SmallPtrSet<const Constant*, 64> Visited;
diff --git a/llvm/lib/Transforms/IPO/GlobalDCE.cpp b/llvm/lib/Transforms/IPO/GlobalDCE.cpp
index dc99492990a..76d1287fb74 100644
--- a/llvm/lib/Transforms/IPO/GlobalDCE.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalDCE.cpp
@@ -42,6 +42,7 @@ namespace {
private:
SmallPtrSet<GlobalValue*, 32> AliveGlobals;
+ SmallPtrSet<Constant *, 8> SeenConstants;
/// GlobalIsNeeded - mark the specific global value as needed, and
/// recursively mark anything that it uses as also needed.
@@ -151,6 +152,7 @@ bool GlobalDCE::runOnModule(Module &M) {
// Make sure that all memory is released
AliveGlobals.clear();
+ SeenConstants.clear();
return Changed;
}
@@ -190,12 +192,15 @@ void GlobalDCE::GlobalIsNeeded(GlobalValue *G) {
void GlobalDCE::MarkUsedGlobalsAsNeeded(Constant *C) {
if (GlobalValue *GV = dyn_cast<GlobalValue>(C))
return GlobalIsNeeded(GV);
-
+
// Loop over all of the operands of the constant, adding any globals they
// use to the list of needed globals.
- for (User::op_iterator I = C->op_begin(), E = C->op_end(); I != E; ++I)
- if (Constant *OpC = dyn_cast<Constant>(*I))
- MarkUsedGlobalsAsNeeded(OpC);
+ for (User::op_iterator I = C->op_begin(), E = C->op_end(); I != E; ++I) {
+ // If we've already processed this constant there's no need to do it again.
+ Constant *Op = cast<Constant>(*I);
+ if (SeenConstants.insert(Op))
+ MarkUsedGlobalsAsNeeded(Op);
+ }
}
// RemoveUnusedGlobalValue - Loop over all of the uses of the specified
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