Changes in directory llvm/lib/Transforms/IPO:
ArgumentPromotion.cpp updated: 1.25 -> 1.26
---
Log message:
Another attempt at making ArgPromotion smarter. This patch no longer breaks
Burg.
---
Diffs of the changes: (+49 -1)
ArgumentPromotion.cpp | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 49 insertions(+), 1 deletion(-)
Index: llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
diff -u llvm/lib/Transforms/IPO/ArgumentPromotion.cpp:1.25
llvm/lib/Transforms/IPO/ArgumentPromotion.cpp:1.26
--- llvm/lib/Transforms/IPO/ArgumentPromotion.cpp:1.25 Fri Sep 15 12:24:45 2006
+++ llvm/lib/Transforms/IPO/ArgumentPromotion.cpp Thu Sep 28 18:02:22 2006
@@ -179,6 +179,53 @@
return true;
}
+/// AccessOccursOnPath - Returns true if and only if a load or GEP instruction
+/// on Pointer occurs in Path, or in every control-flow path that succeeds it.
+bool AccessOccursOnPath(Value* V, BasicBlock* Start) {
+ std::vector<BasicBlock*> Worklist;
+ Worklist.push_back(Start);
+
+ std::set<BasicBlock*> Visited;
+
+ while (!Worklist.empty()) {
+ BasicBlock* BB = Worklist.back();
+ Worklist.pop_back();
+ Visited.insert(BB);
+
+ bool ContainsAccess = false;
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
+ if (isa<LoadInst>(I)) {
+ for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); OI
!= OE; ++OI)
+ if (*OI == V) {
+ ContainsAccess = true;
+ break;
+ }
+ } else if (isa<GetElementPtrInst>(I)) {
+ for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); OI
!= OE; ++OI)
+ if (*OI == V) {
+ ContainsAccess = AccessOccursOnPath(I, I->getParent());
+ break;
+ }
+ }
+
+ if (ContainsAccess)
+ break;
+ }
+
+ if (ContainsAccess) continue;
+
+ TerminatorInst* TI = BB->getTerminator();
+ if (isa<BranchInst>(TI) || isa<SwitchInst>(TI)) {
+ for (unsigned i = 0; i < TI->getNumSuccessors(); ++i)
+ if (!Visited.count(TI->getSuccessor(i)))
+ Worklist.push_back(TI->getSuccessor(i));
+ } else {
+ return false;
+ }
+ }
+
+ return true;
+}
/// isSafeToPromoteArgument - As you might guess from the name of this method,
/// it checks to see if it is both safe and useful to promote the argument.
@@ -252,7 +299,8 @@
// of the pointer in the entry block of the function) or if we can prove that
// all pointers passed in are always to legal locations (for example, no null
// pointers are passed in, no pointers to free'd memory, etc).
- if (!HasLoadInEntryBlock && !AllCalleesPassInValidPointerForArgument(Arg))
+ if (!AccessOccursOnPath(Arg, Arg->getParent()->begin()) &&
+ !AllCalleesPassInValidPointerForArgument(Arg))
return false; // Cannot prove that this is safe!!
// Okay, now we know that the argument is only used by load instructions and
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