Make ConstantFoldConstantExpression recursively visit the entire
ConstantExpr, not just the top-level operator. This allows it to
fold many more constants.
Also, make GlobalOpt call ConstantFoldConstantExpression on
GlobalVariable initializers.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89659 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 1cdadbf..8d60907 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -671,8 +671,13 @@
Constant *llvm::ConstantFoldConstantExpression(ConstantExpr *CE,
const TargetData *TD) {
SmallVector<Constant*, 8> Ops;
- for (User::op_iterator i = CE->op_begin(), e = CE->op_end(); i != e; ++i)
- Ops.push_back(cast<Constant>(*i));
+ for (User::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);
+ Ops.push_back(NewC);
+ }
if (CE->isCompare())
return ConstantFoldCompareInstOperands(CE->getPredicate(), Ops[0], Ops[1],
@@ -687,6 +692,10 @@
/// attempting to fold instructions like loads and stores, which have no
/// constant expression form.
///
+/// TODO: This function neither utilizes nor preserves nsw/nuw/inbounds/etc
+/// information, due to only being passed an opcode and operands. Constant
+/// folding using this function strips this information.
+///
Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
Constant* const* Ops, unsigned NumOps,
const TargetData *TD) {
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 442f2fb..4635d0e 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -1898,6 +1898,15 @@
// Global variables without names cannot be referenced outside this module.
if (!GV->hasName() && !GV->isDeclaration())
GV->setLinkage(GlobalValue::InternalLinkage);
+ // Simplify the initializer.
+ if (GV->hasInitializer())
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GV->getInitializer())) {
+ TargetData *TD = getAnalysisIfAvailable<TargetData>();
+ Constant *New = ConstantFoldConstantExpression(CE, TD);
+ if (New && New != CE)
+ GV->setInitializer(New);
+ }
+ // Do more involved optimizations if the global is internal.
if (!GV->isConstant() && GV->hasLocalLinkage() &&
GV->hasInitializer())
Changed |= ProcessInternalGlobal(GV, GVI);