Subzero: Randomly insert nops.
Adds command line options -nop-insertion, -nop-insertion-probability=X, and -max-nops-per-instruction=X.
BUG=none
R=jvoung@chromium.org, stichnot@chromium.org
Review URL: https://codereview.chromium.org/463563006
diff --git a/src/IceTargetLowering.cpp b/src/IceTargetLowering.cpp
index 0034de5..057a3ea 100644
--- a/src/IceTargetLowering.cpp
+++ b/src/IceTargetLowering.cpp
@@ -22,8 +22,25 @@
#include "IceTargetLowering.h"
#include "IceTargetLoweringX8632.h"
+#include "llvm/Support/CommandLine.h"
+
namespace Ice {
+namespace {
+
+namespace cl = llvm::cl;
+cl::opt<bool> DoNopInsertion("nop-insertion", cl::desc("Randomly insert NOPs"),
+ cl::init(false));
+
+cl::opt<int> MaxNopsPerInstruction(
+ "max-nops-per-instruction",
+ cl::desc("Max number of nops to insert per instruction"), cl::init(1));
+
+cl::opt<int> NopProbabilityAsPercentage(
+ "nop-insertion-percentage",
+ cl::desc("Nop insertion probability as percentage"), cl::init(10));
+} // end of anonymous namespace
+
void LoweringContext::init(CfgNode *N) {
Node = N;
Begin = getNode()->getInsts().begin();
@@ -90,6 +107,20 @@
Context.advanceNext();
}
+bool TargetLowering::shouldDoNopInsertion() const { return DoNopInsertion; }
+
+void TargetLowering::doNopInsertion() {
+ Inst *I = *Context.getCur();
+ bool ShouldSkip = llvm::isa<InstFakeUse>(I) || llvm::isa<InstFakeDef>(I) ||
+ llvm::isa<InstFakeKill>(I) || I->isRedundantAssign() ||
+ I->isDeleted();
+ if (!ShouldSkip) {
+ for (int I = 0; I < MaxNopsPerInstruction; ++I) {
+ randomlyInsertNop(NopProbabilityAsPercentage / 100.0);
+ }
+ }
+}
+
// Lowers a single instruction according to the information in
// Context, by checking the Context.Cur instruction kind and calling
// the appropriate lowering method. The lowering method should insert
