Reapply r185393.
Original commit message:
Remove floating point computations from SpillPlacement.cpp.
Patch by Benjamin Kramer!
Use the BlockFrequency class instead of floats in the Hopfield network
computations. This rescales the node Bias field from a [-2;2] float
range to two block frequencies BiasN and BiasP pulling in opposite
directions. This construct has a more predictable behavior when block
frequencies saturate.
The per-node scaling factors are no longer necessary, assuming the block
frequencies around a bundle are consistent.
This patch can cause the register allocator to make different spilling
decisions. The differences should be small.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186434 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SpillPlacement.h b/lib/CodeGen/SpillPlacement.h
index fc412f8..a0480d5 100644
--- a/lib/CodeGen/SpillPlacement.h
+++ b/lib/CodeGen/SpillPlacement.h
@@ -30,6 +30,7 @@
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/Support/BlockFrequency.h"
namespace llvm {
@@ -57,7 +58,7 @@
SmallVector<unsigned, 8> RecentPositive;
// Block frequencies are computed once. Indexed by block number.
- SmallVector<float, 4> BlockFrequency;
+ SmallVector<BlockFrequency, 4> BlockFrequencies;
public:
static char ID; // Pass identification, replacement for typeid.
@@ -140,7 +141,9 @@
/// getBlockFrequency - Return the estimated block execution frequency per
/// function invocation.
float getBlockFrequency(unsigned Number) const {
- return BlockFrequency[Number];
+ // FIXME: Return the BlockFrequency directly.
+ const float Scale = 1.0f / BlockFrequency::getEntryFrequency();
+ return BlockFrequencies[Number].getFrequency() * Scale;
}
private: