Fix a nasty bug that caused us to unroll EXTREMELY large loops due to overflow
in the size calculation.
This is not something you want to see:
Loop Unroll: F[main] Loop %no_exit Loop Size = 2 Trip Count = 2147483648 - UNROLLING!
The problem was that 2*2147483648 == 0.
Now we get:
Loop Unroll: F[main] Loop %no_exit Loop Size = 2 Trip Count = 2147483648 - TOO LARGE: 4294967296>100
Thanks to some anonymous person playing with the demo page that repeatedly
caused zion to go into swapping land. That's one way to ensure you'll get
a quick bugfix. :)
Testcase here: Transforms/LoopUnroll/2004-05-13-DontUnrollTooMuch.ll
llvm-svn: 13564
diff --git a/llvm/lib/Transforms/Scalar/LoopUnroll.cpp b/llvm/lib/Transforms/Scalar/LoopUnroll.cpp
index 3314820..a9cced5 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnroll.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnroll.cpp
@@ -139,9 +139,9 @@
DEBUG(std::cerr << "Loop Unroll: F[" << BB->getParent()->getName()
<< "] Loop %" << BB->getName() << " Loop Size = " << LoopSize
<< " Trip Count = " << TripCount << " - ");
- if (LoopSize*TripCount > UnrollThreshold) {
- DEBUG(std::cerr << "TOO LARGE: " << LoopSize*TripCount << ">"
- << UnrollThreshold << "\n");
+ uint64_t Size = (uint64_t)LoopSize*(uint64_t)TripCount;
+ if (Size > UnrollThreshold) {
+ DEBUG(std::cerr << "TOO LARGE: " << Size << ">" << UnrollThreshold << "\n");
return Changed;
}
DEBUG(std::cerr << "UNROLLING!\n");