Changes in directory llvm/lib/VMCore:
Globals.cpp updated: 1.16 -> 1.17
---
Log message:
revert my previous change, something strange is happening.
---
Diffs of the changes: (+21 -29)
Globals.cpp | 50 +++++++++++++++++++++-----------------------------
1 files changed, 21 insertions(+), 29 deletions(-)
Index: llvm/lib/VMCore/Globals.cpp
diff -u llvm/lib/VMCore/Globals.cpp:1.16 llvm/lib/VMCore/Globals.cpp:1.17
--- llvm/lib/VMCore/Globals.cpp:1.16 Sun Feb 25 15:06:13 2007
+++ llvm/lib/VMCore/Globals.cpp Sun Feb 25 22:43:19 2007
@@ -22,18 +22,20 @@
// GlobalValue Class
//===----------------------------------------------------------------------===//
-/// removeDeadUsersOfConstant - If the specified constantexpr is dead, remove
-/// it. This involves recursively eliminating any dead users of the
-/// constantexpr.
-static bool removeDeadUsersOfConstant(Constant *C) {
+/// This could be named "SafeToDestroyGlobalValue". It just makes sure that
+/// there are no non-constant uses of this GlobalValue. If there aren't then
+/// this and the transitive closure of the constants can be deleted. See the
+/// destructor for details.
+static bool removeDeadConstantUsers(Constant* C) {
if (isa<GlobalValue>(C)) return false; // Cannot remove this
- while (!C->use_empty()) {
- Constant *User = dyn_cast<Constant>(C->use_back());
- if (!User) return false; // Non-constant usage;
- if (!removeDeadUsersOfConstant(User))
- return false; // Constant wasn't dead
- }
+ while (!C->use_empty())
+ if (Constant *User = dyn_cast<Constant>(C->use_back())) {
+ if (!removeDeadConstantUsers(User))
+ return false; // Constant wasn't dead
+ } else {
+ return false; // Non-constant usage;
+ }
C->destroyConstant();
return true;
@@ -43,27 +45,17 @@
/// off of this global value, remove them. This method is useful for clients
/// that want to check to see if a global is unused, but don't want to deal
/// with potentially dead constants hanging off of the globals.
+///
+/// This function returns true if the global value is now dead. If all
+/// users of this global are not dead, this method may return false and
+/// leave some of them around.
void GlobalValue::removeDeadConstantUsers() {
-
- Value::use_iterator I = use_begin(), E = use_end();
- Value::use_iterator LastNonDeadUser = E;
- for (; I != E; ++I) {
- if (Constant *User = dyn_cast<Constant>(*I)) {
- if (!removeDeadUsersOfConstant(User)) {
- // If the constant wasn't dead, remember that this was the last live
use
- // and move on to the next constant.
- LastNonDeadUser = I;
- } else {
- // If the constant was dead, then the iterator is invalidated.
- if (LastNonDeadUser == E) {
- I = use_begin();
- if (I == E) break;
- } else {
- I = LastNonDeadUser;
- }
- }
+ while(!use_empty()) {
+ if (Constant* User = dyn_cast<Constant>(use_back())) {
+ if (!::removeDeadConstantUsers(User))
+ return; // Constant wasn't dead
} else {
- LastNonDeadUser = I;
+ return; // Non-constant usage;
}
}
}
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