[llvm-commits] CVS: llvm/lib/Transforms/Utils/Local.cpp

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Utils:

Local.cpp updated: 1.38 -> 1.39
---
Log message:

DCE intrinsic instructions without side effects.


---
Diffs of the changes:  (+20 -1)

 Local.cpp |   21 ++++++++++++++++++++-
 1 files changed, 20 insertions(+), 1 deletion(-)


Index: llvm/lib/Transforms/Utils/Local.cpp
diff -u llvm/lib/Transforms/Utils/Local.cpp:1.38 llvm/lib/Transforms/Utils/Local.cpp:1.39
--- llvm/lib/Transforms/Utils/Local.cpp:1.38	Fri Apr 29 00:55:35 2005
+++ llvm/lib/Transforms/Utils/Local.cpp	Fri May  6 00:27:34 2005
@@ -373,7 +373,26 @@
 //
 
 bool llvm::isInstructionTriviallyDead(Instruction *I) {
-  return I->use_empty() && !I->mayWriteToMemory() && !isa<TerminatorInst>(I);
+  if (!I->use_empty() || isa<TerminatorInst>(I)) return false;
+ 
+  if (!I->mayWriteToMemory()) return true;
+
+  if (CallInst *CI = dyn_cast<CallInst>(I))
+    if (Function *F = CI->getCalledFunction())
+      switch (F->getIntrinsicID()) {
+      default: break;
+      case Intrinsic::vastart:
+      case Intrinsic::vacopy:
+      case Intrinsic::returnaddress:
+      case Intrinsic::frameaddress:
+      case Intrinsic::isunordered:
+      case Intrinsic::ctpop:
+      case Intrinsic::ctlz:
+      case Intrinsic::cttz:
+      case Intrinsic::sqrt:
+        return true;             // These intrinsics have no side effects.
+      }
+  return false;
 }
 
 // dceInstruction - Inspect the instruction at *BBI and figure out if it's