Expose the low level DCE mechanism to external users
Refactor code to support it
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1083 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/DCE.cpp b/lib/Transforms/Scalar/DCE.cpp
index 71a7f5a..ac3ae7b 100644
--- a/lib/Transforms/Scalar/DCE.cpp
+++ b/lib/Transforms/Scalar/DCE.cpp
@@ -34,20 +34,30 @@
#include "llvm/Assembly/Writer.h"
#include <algorithm>
-static bool RemoveUnusedDefs(BasicBlock::InstListType &Vals) {
+// dceInstruction - Inspect the instruction at *BBI and figure out if it's
+// [trivially] dead. If so, remove the instruction and update the iterator
+// to point to the instruction that immediately succeeded the original
+// instruction.
+//
+bool opt::DeadCodeElimination::dceInstruction(BasicBlock::InstListType &BBIL,
+ BasicBlock::iterator &BBI) {
+ // Look for un"used" definitions...
+ if ((*BBI)->use_empty() && !(*BBI)->hasSideEffects() &&
+ !isa<TerminatorInst>(*BBI)) {
+ delete BBIL.remove(BBI); // Bye bye
+ return true;
+ }
+ return false;
+}
+
+static inline bool RemoveUnusedDefs(BasicBlock::InstListType &Vals) {
bool Changed = false;
for (BasicBlock::InstListType::iterator DI = Vals.begin();
- DI != Vals.end()-1; ) {
- // Look for un"used" definitions...
- if ((*DI)->use_empty() && !(*DI)->hasSideEffects()) {
- // Bye bye
- //cerr << "Removing: " << *DI;
- delete Vals.remove(DI);
+ DI != Vals.end(); )
+ if (opt::DeadCodeElimination::dceInstruction(Vals, DI))
Changed = true;
- } else {
+ else
++DI;
- }
- }
return Changed;
}