#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/ValueHandle.h"
+#include <algorithm>
using namespace llvm;
using namespace llvm::PatternMatch;
return ConstantExpr::getICmp(Pred,
ConstantExpr::getAdd(LHSOffset, LHSNoBound),
ConstantExpr::getAdd(RHSOffset, RHSNoBound));
+
+ // If one side of the equality comparison must come from a noalias call
+ // (meaning a system memory allocation function), and the other side must
+ // come from a pointer that cannot overlap with dynamically-allocated
+ // memory within the lifetime of the current function (allocas, byval
+ // arguments, globals), then determine the comparison result here.
+ SmallVector<Value *, 8> LHSUObjs, RHSUObjs;
+ GetUnderlyingObjects(LHS, LHSUObjs, DL);
+ GetUnderlyingObjects(RHS, RHSUObjs, DL);
+
+ // Is the set of underlying objects all noalias calls?
+ auto IsNAC = [](SmallVectorImpl<Value *> &Objects) {
+ return std::all_of(Objects.begin(), Objects.end(),
+ [](Value *V){ return isNoAliasCall(V); });
+ };
+
+ // Is the set of underlying objects all things which must be disjoint from
+ // noalias calls.
+ auto IsAllocDisjoint = [](SmallVectorImpl<Value *> &Objects) {
+ return std::all_of(Objects.begin(), Objects.end(),
+ [](Value *V){
+ if (isa<AllocaInst>(V) || isa<GlobalValue>(V))
+ return true;
+ if (const Argument *A = dyn_cast<Argument>(V))
+ return A->hasByValAttr();
+ return false;
+ });
+ };
+
+ if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) ||
+ (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs)))
+ return ConstantInt::get(GetCompareTy(LHS),
+ !CmpInst::isTrueWhenEqual(Pred));
}
// Otherwise, fail.
--- /dev/null
+; RUN: opt -instsimplify -S < %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@g1 = global i32 0, align 4
+
+; Make sure we can simplify away a pointer comparison between
+; dynamically-allocated memory and a local stack allocation.
+; void p()
+; {
+; int *mData;
+; int mStackData[10];
+; mData = new int[12];
+; if (mData != mStackData) {
+; delete[] mData;
+; }
+; }
+
+define void @_Z2p1v() #0 {
+ %mStackData = alloca [10 x i32], align 16
+ %1 = bitcast [10 x i32]* %mStackData to i8*
+ %2 = tail call noalias i8* @_Znam(i64 48) #4
+ %3 = bitcast i8* %2 to i32*
+ %4 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
+ %5 = icmp eq i32* %3, %4
+ br i1 %5, label %7, label %6
+
+; CHECK-LABEL: @_Z2p1v
+; CHECK-NOT: icmp
+; CHECK: ret void
+
+; <label>:6 ; preds = %0
+ call void @_ZdaPv(i8* %2) #5
+ br label %7
+
+; <label>:7 ; preds = %0, %6
+ ret void
+}
+
+; Also check a more-complicated case with multiple underlying objects.
+
+define void @_Z2p2bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
+ %mStackData = alloca [10 x i32], align 16
+ %1 = bitcast [10 x i32]* %mStackData to i8*
+ %2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
+ %3 = select i1 %b1, i32* %2, i32* @g1
+ %4 = tail call noalias i8* @_Znam(i64 48) #4
+ %5 = tail call noalias i8* @_Znam(i64 48) #4
+ %.v = select i1 %b2, i8* %4, i8* %5
+ %6 = bitcast i8* %.v to i32*
+ %7 = icmp eq i32* %6, %3
+ br i1 %7, label %9, label %8
+
+; CHECK-LABEL: @_Z2p2bb
+; CHECK-NOT: icmp
+; CHECK: ret void
+
+; <label>:8 ; preds = %0
+ call void @_ZdaPv(i8* %4) #5
+ call void @_ZdaPv(i8* %5) #5
+ br label %9
+
+; <label>:9 ; preds = %0, %8
+ ret void
+}
+
+; Here's another case involving multiple underlying objects, but this time we
+; must keep the comparison (it might involve a regular pointer-typed function
+; argument).
+
+define void @_Z4nopebbPi(i1 zeroext %b1, i1 zeroext %b2, i32* readnone %q) #0 {
+ %mStackData = alloca [10 x i32], align 16
+ %1 = bitcast [10 x i32]* %mStackData to i8*
+ %2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
+ %3 = select i1 %b1, i32* %2, i32* %q
+ %4 = tail call noalias i8* @_Znam(i64 48) #4
+ %5 = tail call noalias i8* @_Znam(i64 48) #4
+ %.v = select i1 %b2, i8* %4, i8* %5
+ %6 = bitcast i8* %.v to i32*
+ %7 = icmp eq i32* %6, %3
+ br i1 %7, label %9, label %8
+
+; CHECK-LABEL: @_Z4nopebbPi
+; CHECK: icmp
+; CHECK: ret void
+
+; <label>:8 ; preds = %0
+ call void @_ZdaPv(i8* %4) #5
+ call void @_ZdaPv(i8* %5) #5
+ br label %9
+
+; <label>:9 ; preds = %0, %8
+ ret void
+}
+
+; Function Attrs: nobuiltin
+declare noalias i8* @_Znam(i64) #2
+
+; Function Attrs: nobuiltin nounwind
+declare void @_ZdaPv(i8*) #3
+
+attributes #0 = { uwtable }
+attributes #1 = { nounwind }
+attributes #2 = { nobuiltin }
+attributes #3 = { nobuiltin nounwind }
+attributes #4 = { builtin }
+attributes #5 = { builtin nounwind }
+