[PATCH] D59009: [BasicAA] Peak through IntToPtr(Load(%object))

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
fhahn added reviewers: nlopes, efriedma, asbirlea, hfinkel.
Herald added subscribers: jdoerfert, hiraditya.
Herald added a project: LLVM.

If we use a pointer generated by inttoptr(load(%object)), use object as
underlying object. I am not entirely sure if this is valid given the
GetUnderlyingObject semantics and would appreciate your  feedback!


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D59009

Files:
  llvm/lib/Analysis/BasicAliasAnalysis.cpp
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Analysis/BasicAA/inttoptr.ll


Index: llvm/test/Analysis/BasicAA/inttoptr.ll
===================================================================
--- /dev/null
+++ llvm/test/Analysis/BasicAA/inttoptr.ll
@@ -0,0 +1,47 @@
+; RUN: opt -basicaa -aa-eval -print-no-aliases < %s 2>&1 --disable-output | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+
+%struct.data = type <{ i64*, i64, [20 x i64] }>
+
+declare void @init(%struct.data** %ptr)
+
+; CHECK-LABEL: Function: test1
+; CHECK: NoAlias: i64* %base, i64* %gep.2
+
+define void @test1(i64 %arg) {
+  %loc = alloca %struct.data*, align 8
+  %base = bitcast %struct.data** %loc to i64*
+  call void @init(%struct.data** %loc )
+
+  %addr = load i64, i64* %base, align 8
+  %ptr = inttoptr i64 %addr to %struct.data*
+  %offset.ptr = getelementptr inbounds %struct.data, %struct.data* %ptr, i64 0, i32 1
+  %offset = load i64, i64* %offset.ptr, align 8, !range !13
+  %gep.1 = getelementptr inbounds %struct.data, %struct.data* %ptr, i64 0, i32 2
+  %gep.2 = getelementptr inbounds [20 x i64], [20 x i64]* %gep.1, i64 0, i64 %offset
+  store i64 1, i64* %gep.2, align 8
+  ret void
+}
+
+
+; CHECK-LABEL: Function: test2
+; CHECK-NOT: NoAlias: i64* %base, i64* %gep.2
+define void @test2(i64 %arg) {
+  %loc = alloca %struct.data*, align 8
+  %base = bitcast %struct.data** %loc to i64*
+  call void @init(%struct.data** %loc )
+
+  %addr = load i64, i64* %base, align 8
+  %strip = and i64 %addr, 72057594037927928
+  %ptr = inttoptr i64 %strip to %struct.data*
+  %offset.ptr = getelementptr inbounds %struct.data, %struct.data* %ptr, i64 0, i32 1
+  %offset = load i64, i64* %offset.ptr, align 8, !range !13
+  %gep.1 = getelementptr inbounds %struct.data, %struct.data* %ptr, i64 0, i32 2
+  %gep.2 = getelementptr inbounds [20 x i64], [20 x i64]* %gep.1, i64 0, i64 %offset
+  store i64 1, i64* %gep.2, align 8
+  ret void
+}
+
+
+!13 = !{i64 0, i64 20}
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -3720,6 +3720,11 @@
   if (!V->getType()->isPointerTy())
     return V;
   for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) {
+    Value *Loc;
+    if (match(V, m_IntToPtr(m_Load(m_Value(Loc))))) {
+      return Loc;
+    }
+
     if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
       V = GEP->getPointerOperand();
     } else if (Operator::getOpcode(V) == Instruction::BitCast ||
Index: llvm/lib/Analysis/BasicAliasAnalysis.cpp
===================================================================
--- llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -41,6 +41,7 @@
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/Instruction.h"
+#include "llvm/IR/PatternMatch.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Intrinsics.h"
@@ -62,6 +63,7 @@
 #define DEBUG_TYPE "basicaa"
 
 using namespace llvm;
+using namespace PatternMatch;
 
 /// Enable analysis of recursive PHI nodes.
 static cl::opt<bool> EnableRecPhiAnalysis("basicaa-recphi", cl::Hidden,
@@ -469,6 +471,11 @@
       continue;
     }
 
+    Value *Loc;
+    if (match(Op, m_IntToPtr(m_Load(m_Value(Loc))))) {
+      Decomposed.Base = Loc;
+      return false;
+    }
     const GEPOperator *GEPOp = dyn_cast<GEPOperator>(Op);
     if (!GEPOp) {
       if (const auto *Call = dyn_cast<CallBase>(V)) {


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