Treat Mul just like Add and Subtract
Like adds and subtracts, muls ripple only to the left so we can use
the same logic.
While we're here, add a print method to DemandedBits so it can be used
with -analyze, which we'll use in the testcase.
llvm-svn: 249686
diff --git a/llvm/lib/Analysis/DemandedBits.cpp b/llvm/lib/Analysis/DemandedBits.cpp
index 775cbac..6f92ba6 100644
--- a/llvm/lib/Analysis/DemandedBits.cpp
+++ b/llvm/lib/Analysis/DemandedBits.cpp
@@ -25,6 +25,7 @@
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/BasicBlock.h"
@@ -131,6 +132,7 @@
break;
case Instruction::Add:
case Instruction::Sub:
+ case Instruction::Mul:
// Find the highest live output bit. We don't need any more input
// bits than that (adds, and thus subtracts, ripple only to the
// left).
@@ -368,6 +370,16 @@
!isAlwaysLive(I);
}
+void DemandedBits::print(raw_ostream &OS, const Module *M) const {
+ // This is gross. But the alternative is making all the state mutable
+ // just because of this one debugging method.
+ const_cast<DemandedBits*>(this)->performAnalysis();
+ for (auto &KV : AliveBits) {
+ OS << "DemandedBits: 0x" << utohexstr(KV.second.getLimitedValue()) << " for "
+ << *KV.first << "\n";
+ }
+}
+
FunctionPass *llvm::createDemandedBitsPass() {
return new DemandedBits();
}