Default lowering for experimental.widenable.condition
Introduces a pass that provides default lowering strategy for the
`experimental.widenable.condition` intrinsic, replacing all its uses with
`i1 true`.
Differential Revision: https://reviews.llvm.org/D56096
Reviewed By: reames
llvm-svn: 352739
diff --git a/llvm/lib/Transforms/Scalar/LowerWidenableCondition.cpp b/llvm/lib/Transforms/Scalar/LowerWidenableCondition.cpp
new file mode 100644
index 0000000..6a83d06
--- /dev/null
+++ b/llvm/lib/Transforms/Scalar/LowerWidenableCondition.cpp
@@ -0,0 +1,86 @@
+//===- LowerWidenableCondition.cpp - Lower the guard intrinsic ---------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass lowers the llvm.widenable.condition intrinsic to default value
+// which is i1 true.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar/LowerWidenableCondition.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Analysis/GuardUtils.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/InstIterator.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/PatternMatch.h"
+#include "llvm/Pass.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/GuardUtils.h"
+
+using namespace llvm;
+
+namespace {
+struct LowerWidenableConditionLegacyPass : public FunctionPass {
+ static char ID;
+ LowerWidenableConditionLegacyPass() : FunctionPass(ID) {
+ initializeLowerWidenableConditionLegacyPassPass(
+ *PassRegistry::getPassRegistry());
+ }
+
+ bool runOnFunction(Function &F) override;
+};
+}
+
+static bool lowerWidenableCondition(Function &F) {
+ // Check if we can cheaply rule out the possibility of not having any work to
+ // do.
+ auto *WCDecl = F.getParent()->getFunction(
+ Intrinsic::getName(Intrinsic::experimental_widenable_condition));
+ if (!WCDecl || WCDecl->use_empty())
+ return false;
+
+ using namespace llvm::PatternMatch;
+ SmallVector<CallInst *, 8> ToLower;
+ for (auto &I : instructions(F))
+ if (match(&I, m_Intrinsic<Intrinsic::experimental_widenable_condition>()))
+ ToLower.push_back(cast<CallInst>(&I));
+
+ if (ToLower.empty())
+ return false;
+
+ for (auto *CI : ToLower) {
+ CI->replaceAllUsesWith(ConstantInt::getTrue(CI->getContext()));
+ CI->eraseFromParent();
+ }
+ return true;
+}
+
+bool LowerWidenableConditionLegacyPass::runOnFunction(Function &F) {
+ return lowerWidenableCondition(F);
+}
+
+char LowerWidenableConditionLegacyPass::ID = 0;
+INITIALIZE_PASS(LowerWidenableConditionLegacyPass, "lower-widenable-condition",
+ "Lower the widenable condition to default true value", false,
+ false)
+
+Pass *llvm::createLowerWidenableConditionPass() {
+ return new LowerWidenableConditionLegacyPass();
+}
+
+PreservedAnalyses LowerWidenableConditionPass::run(Function &F,
+ FunctionAnalysisManager &AM) {
+ if (lowerWidenableCondition(F))
+ return PreservedAnalyses::none();
+
+ return PreservedAnalyses::all();
+}