From 33d1dc000806708d65597da6a810bb450664f11d Mon Sep 17 00:00:00 2001 From: Charles Davis Date: Wed, 25 Feb 2015 05:10:25 +0000 Subject: [PATCH] [IC] Turn non-null MD on pointer loads to range MD on integer loads. Summary: This change fixes the FIXME that you recently added when you committed (a modified version of) my patch. When `InstCombine` combines a load and store of an pointer to those of an equivalently-sized integer, it currently drops any `!nonnull` metadata that might be present. This change replaces `!nonnull` metadata with `!range !{ 1, -1 }` metadata instead. Reviewers: chandlerc Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D7621 llvm-svn: 230462 --- llvm/include/llvm/IR/MDBuilder.h | 3 +++ llvm/lib/IR/MDBuilder.cpp | 10 +++++++--- .../InstCombine/InstCombineLoadStoreAlloca.cpp | 22 ++++++++++++++++++---- .../Transforms/InstCombine/loadstore-metadata.ll | 16 ++++++++++++---- 4 files changed, 40 insertions(+), 11 deletions(-) diff --git a/llvm/include/llvm/IR/MDBuilder.h b/llvm/include/llvm/IR/MDBuilder.h index 91a6685..51b8b02 100644 --- a/llvm/include/llvm/IR/MDBuilder.h +++ b/llvm/include/llvm/IR/MDBuilder.h @@ -67,6 +67,9 @@ public: /// \brief Return metadata describing the range [Lo, Hi). MDNode *createRange(const APInt &Lo, const APInt &Hi); + /// \brief Return metadata describing the range [Lo, Hi). + MDNode *createRange(Constant *Lo, Constant *Hi); + //===------------------------------------------------------------------===// // AA metadata. //===------------------------------------------------------------------===// diff --git a/llvm/lib/IR/MDBuilder.cpp b/llvm/lib/IR/MDBuilder.cpp index d6d03b4..a901011 100644 --- a/llvm/lib/IR/MDBuilder.cpp +++ b/llvm/lib/IR/MDBuilder.cpp @@ -55,14 +55,18 @@ MDNode *MDBuilder::createBranchWeights(ArrayRef Weights) { MDNode *MDBuilder::createRange(const APInt &Lo, const APInt &Hi) { assert(Lo.getBitWidth() == Hi.getBitWidth() && "Mismatched bitwidths!"); + + Type *Ty = IntegerType::get(Context, Lo.getBitWidth()); + return createRange(ConstantInt::get(Ty, Lo), ConstantInt::get(Ty, Hi)); +} + +MDNode *MDBuilder::createRange(Constant *Lo, Constant *Hi) { // If the range is everything then it is useless. if (Hi == Lo) return nullptr; // Return the range [Lo, Hi). - Type *Ty = IntegerType::get(Context, Lo.getBitWidth()); - Metadata *Range[2] = {createConstant(ConstantInt::get(Ty, Lo)), - createConstant(ConstantInt::get(Ty, Hi))}; + Metadata *Range[2] = {createConstant(Lo), createConstant(Hi)}; return MDNode::get(Context, Range); } diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp index 1b99d87..b9eb986 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp @@ -17,6 +17,7 @@ #include "llvm/IR/DataLayout.h" #include "llvm/IR/LLVMContext.h" #include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/MDBuilder.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h" #include "llvm/Transforms/Utils/Local.h" using namespace llvm; @@ -309,6 +310,7 @@ static LoadInst *combineLoadToNewType(InstCombiner &IC, LoadInst &LI, Type *NewT LoadInst *NewLoad = IC.Builder->CreateAlignedLoad( IC.Builder->CreateBitCast(Ptr, NewTy->getPointerTo(AS)), LI.getAlignment(), LI.getName()); + MDBuilder MDB(NewLoad->getContext()); for (const auto &MDPair : MD) { unsigned ID = MDPair.first; MDNode *N = MDPair.second; @@ -335,15 +337,27 @@ static LoadInst *combineLoadToNewType(InstCombiner &IC, LoadInst &LI, Type *NewT break; case LLVMContext::MD_nonnull: - // FIXME: We should translate this into range metadata for integer types - // and vice versa. - if (NewTy->isPointerTy()) + // This only directly applies if the new type is also a pointer. + if (NewTy->isPointerTy()) { NewLoad->setMetadata(ID, N); + break; + } + // If it's integral now, translate it to !range metadata. + if (NewTy->isIntegerTy()) { + auto *ITy = cast(NewTy); + auto *NullInt = ConstantExpr::getPtrToInt( + ConstantPointerNull::get(cast(Ptr->getType())), ITy); + auto *NonNullInt = + ConstantExpr::getAdd(NullInt, ConstantInt::get(ITy, 1)); + NewLoad->setMetadata(LLVMContext::MD_range, + MDB.createRange(NonNullInt, NullInt)); + } break; case LLVMContext::MD_range: // FIXME: It would be nice to propagate this in some way, but the type - // conversions make it hard. + // conversions make it hard. If the new type is a pointer, we could + // translate it to !nonnull metadata. break; } } diff --git a/llvm/test/Transforms/InstCombine/loadstore-metadata.ll b/llvm/test/Transforms/InstCombine/loadstore-metadata.ll index e5b0449..be55fa62 100644 --- a/llvm/test/Transforms/InstCombine/loadstore-metadata.ll +++ b/llvm/test/Transforms/InstCombine/loadstore-metadata.ll @@ -82,21 +82,29 @@ exit: define void @test_load_cast_combine_nonnull(float** %ptr) { ; We can't preserve nonnull metadata when converting a load of a pointer to -; a load of an integer. -; FIXME: We should really transform this into range metadata and vice versa. +; a load of an integer. Instead, we translate it to range metadata. +; FIXME: We should also transform range metadata back into nonnull metadata. +; FIXME: This test is very fragile. If any LABEL lines are added after +; this point, the test will fail, because this test depends on a metadata tuple, +; which is always emitted at the end of the file. At some point, we should +; consider an option to the IR printer to emit MD tuples after the function +; that first uses them--this will allow us to refer to them like this and not +; have the tests break. For now, this function must always come last in this +; file, and no LABEL lines are to be added after this point. ; ; CHECK-LABEL: @test_load_cast_combine_nonnull( -; CHECK: %[[V:.*]] = load i64* %{{.*}} +; CHECK: %[[V:.*]] = load i64* %{{.*}}, !range ![[MD:[0-9]+]] ; CHECK-NOT: !nonnull ; CHECK: store i64 %[[V]], i64* entry: %p = load float** %ptr, !nonnull !3 %gep = getelementptr float** %ptr, i32 42 store float* %p, float** %gep - ret void } +; This is the metadata tuple that we reference above: +; CHECK: ![[MD]] = !{i64 1, i64 0} !0 = !{ !1, !1, i64 0 } !1 = !{ !1 } !2 = !{ !2, !1 } -- 2.7.4