Changes in directory llvm/lib/VMCore:
Constants.cpp updated: 1.163 -> 1.164
---
Log message:
add a method to determine whether evaluation of a constant can trap.
---
Diffs of the changes: (+27 -0)
Constants.cpp | 27 +++++++++++++++++++++++++++
1 files changed, 27 insertions(+)
Index: llvm/lib/VMCore/Constants.cpp
diff -u llvm/lib/VMCore/Constants.cpp:1.163 llvm/lib/VMCore/Constants.cpp:1.164
--- llvm/lib/VMCore/Constants.cpp:1.163 Thu Sep 28 18:34:27 2006
+++ llvm/lib/VMCore/Constants.cpp Thu Oct 19 19:27:06 2006
@@ -58,6 +58,33 @@
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!");
+ // The only thing that could possibly trap are constant exprs.
+ const ConstantExpr *CE = dyn_cast<ConstantExpr>(this);
+ if (!CE) return false;
+
+ // ConstantExpr traps if any operands can trap.
+ for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
+ if (getOperand(i)->canTrap())
+ return true;
+
+ // Otherwise, only specific operations can trap.
+ switch (CE->getOpcode()) {
+ default:
+ return false;
+ case Instruction::Div:
+ case Instruction::Rem:
+ // Div and rem can trap if the RHS is not known to be non-zero.
+ if (!isa<ConstantInt>(getOperand(1)) || getOperand(1)->isNullValue())
+ return true;
+ return false;
+ }
+}
+
+
// Static constructor to create a '0' constant of arbitrary type...
Constant *Constant::getNullValue(const Type *Ty) {
switch (Ty->getTypeID()) {
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