[InstCombine] When adding an Instruction and its Users to the worklist at the same...

This way we ensure we immediately revisit the instruction and do any additional optimizations before visiting the users. Otherwise we might visit the users, then the instruction, then users again, then instruction again.

llvm-svn: 299267

diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 5b5c99a..94e7a7f 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2935,8 +2935,8 @@ bool InstCombiner::run() {
         Result->takeName(I);
 
         // Push the new instruction and any users onto the worklist.
-        Worklist.Add(Result);
         Worklist.AddUsersToWorkList(*Result);
+        Worklist.Add(Result);
 
         // Insert the new instruction into the basic block...
         BasicBlock *InstParent = I->getParent();
@@ -2959,8 +2959,8 @@ bool InstCombiner::run() {
         if (isInstructionTriviallyDead(I, &TLI)) {
           eraseInstFromFunction(*I);
         } else {
-          Worklist.Add(I);
           Worklist.AddUsersToWorkList(*I);
+          Worklist.Add(I);
         }
       }
       MadeIRChange = true;