recommit r171298 (add support for PHI nodes to ObjectSizeOffsetVisitor). Hopefully with bugs corrected now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171325 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 155 insertions, 12 deletions

diff --git a/include/llvm/Analysis/MemoryBuiltins.h b/include/llvm/Analysis/MemoryBuiltins.h
index 9502f621b1..73e0e98cfd 100644
--- a/include/llvm/Analysis/MemoryBuiltins.h
+++ b/include/llvm/Analysis/MemoryBuiltins.h
@@ -158,7 +158,7 @@ class ObjectSizeOffsetVisitor
   bool RoundToAlign;
   unsigned IntTyBits;
   APInt Zero;
-  SmallPtrSet<Instruction *, 8> SeenInsts;
+  SmallPtrSet<Value*, 8> SeenInsts;
 
   APInt align(APInt Size, uint64_t Align);
 
diff --git a/lib/Analysis/MemoryBuiltins.cpp b/lib/Analysis/MemoryBuiltins.cpp
index 14815801d1..2eebaad495 100644
--- a/lib/Analysis/MemoryBuiltins.cpp
+++ b/lib/Analysis/MemoryBuiltins.cpp
@@ -385,16 +385,21 @@ ObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const DataLayout *TD,
 
 SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
   V = V->stripPointerCasts();
-  if (Instruction *I = dyn_cast<Instruction>(V)) {
-    // If we have already seen this instruction, bail out. Cycles can happen in
-    // unreachable code after constant propagation.
-    if (!SeenInsts.insert(I))
+
+  if (isa<Instruction>(V) || isa<GEPOperator>(V)) {
+    // If we have already seen this instruction, bail out.
+    if (!SeenInsts.insert(V))
       return unknown();
 
+    SizeOffsetType Ret;
     if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
-      return visitGEPOperator(*GEP);
-    return visit(*I);
+      Ret = visitGEPOperator(*GEP);
+    else
+      Ret = visit(cast<Instruction>(*V));
+    SeenInsts.erase(V);
+    return Ret;
   }
+
   if (Argument *A = dyn_cast<Argument>(V))
     return visitArgument(*A);
   if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V))
@@ -408,8 +413,6 @@ SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
   if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
     if (CE->getOpcode() == Instruction::IntToPtr)
       return unknown(); // clueless
-    if (CE->getOpcode() == Instruction::GetElementPtr)
-      return visitGEPOperator(cast<GEPOperator>(*CE));
   }
 
   DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " << *V
@@ -543,9 +546,21 @@ SizeOffsetType ObjectSizeOffsetVisitor::visitLoadInst(LoadInst&) {
   return unknown();
 }
 
-SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) {
-  // too complex to analyze statically.
-  return unknown();
+SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode &PHI) {
+  if (PHI.getNumIncomingValues() == 0)
+    return unknown();
+
+  SizeOffsetType Ret = compute(PHI.getIncomingValue(0));
+  if (!bothKnown(Ret))
+    return unknown();
+
+  // verify that all PHI incoming pointers have the same size and offset
+  for (unsigned i = 1, e = PHI.getNumIncomingValues(); i != e; ++i) {
+    SizeOffsetType EdgeData = compute(PHI.getIncomingValue(i));
+    if (!bothKnown(EdgeData) || EdgeData != Ret)
+      return unknown();
+  }
+  return Ret;
 }
 
 SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) {
diff --git a/test/Transforms/InstCombine/objsize.ll b/test/Transforms/InstCombine/objsize.ll
index 31a3cb46e4..0ead9d1237 100644
--- a/test/Transforms/InstCombine/objsize.ll
+++ b/test/Transforms/InstCombine/objsize.ll
@@ -256,3 +256,131 @@ xpto:
 return:
   ret i32 7
 }
+
+declare noalias i8* @valloc(i32) nounwind
+
+; CHECK: @test14
+; CHECK: ret i32 6
+define i32 @test14(i32 %a) nounwind {
+  switch i32 %a, label %sw.default [
+    i32 1, label %sw.bb
+    i32 2, label %sw.bb1
+  ]
+
+sw.bb:
+  %call = tail call noalias i8* @malloc(i32 6) nounwind
+  br label %sw.epilog
+
+sw.bb1:
+  %call2 = tail call noalias i8* @calloc(i32 3, i32 2) nounwind
+  br label %sw.epilog
+
+sw.default:
+  %call3 = tail call noalias i8* @valloc(i32 6) nounwind
+  br label %sw.epilog
+
+sw.epilog:
+  %b.0 = phi i8* [ %call3, %sw.default ], [ %call2, %sw.bb1 ], [ %call, %sw.bb ]
+  %1 = tail call i32 @llvm.objectsize.i32(i8* %b.0, i1 false)
+  ret i32 %1
+}
+
+; CHECK: @test15
+; CHECK: llvm.objectsize
+define i32 @test15(i32 %a) nounwind {
+  switch i32 %a, label %sw.default [
+    i32 1, label %sw.bb
+    i32 2, label %sw.bb1
+  ]
+
+sw.bb:
+  %call = tail call noalias i8* @malloc(i32 3) nounwind
+  br label %sw.epilog
+
+sw.bb1:
+  %call2 = tail call noalias i8* @calloc(i32 2, i32 1) nounwind
+  br label %sw.epilog
+
+sw.default:
+  %call3 = tail call noalias i8* @valloc(i32 3) nounwind
+  br label %sw.epilog
+
+sw.epilog:
+  %b.0 = phi i8* [ %call3, %sw.default ], [ %call2, %sw.bb1 ], [ %call, %sw.bb ]
+  %1 = tail call i32 @llvm.objectsize.i32(i8* %b.0, i1 false)
+  ret i32 %1
+}
+
+; CHECK: @test16
+; CHECK: llvm.objectsize
+define i32 @test16(i8* %a, i32 %n) nounwind {
+  %b = alloca [5 x i8], align 1
+  %c = alloca [5 x i8], align 1
+  switch i32 %n, label %sw.default [
+    i32 1, label %sw.bb
+    i32 2, label %sw.bb1
+  ]
+
+sw.bb:
+  %bp = bitcast [5 x i8]* %b to i8*
+  br label %sw.epilog
+
+sw.bb1:
+  %cp = bitcast [5 x i8]* %c to i8*
+  br label %sw.epilog
+
+sw.default:
+  br label %sw.epilog
+
+sw.epilog:
+  %phi = phi i8* [ %a, %sw.default ], [ %cp, %sw.bb1 ], [ %bp, %sw.bb ]
+  %sz = call i32 @llvm.objectsize.i32(i8* %phi, i1 false)
+  ret i32 %sz
+}
+
+; CHECK: @test17
+; CHECK: ret i32 5
+define i32 @test17(i32 %n) nounwind {
+  %b = alloca [5 x i8], align 1
+  %c = alloca [5 x i8], align 1
+  %bp = bitcast [5 x i8]* %b to i8*
+  switch i32 %n, label %sw.default [
+    i32 1, label %sw.bb
+    i32 2, label %sw.bb1
+  ]
+
+sw.bb:
+  br label %sw.epilog
+
+sw.bb1:
+  %cp = bitcast [5 x i8]* %c to i8*
+  br label %sw.epilog
+
+sw.default:
+  br label %sw.epilog
+
+sw.epilog:
+  %phi = phi i8* [ %bp, %sw.default ], [ %cp, %sw.bb1 ], [ %bp, %sw.bb ]
+  %sz = call i32 @llvm.objectsize.i32(i8* %phi, i1 false)
+  ret i32 %sz
+}
+
+@globalalias = alias internal [60 x i8]* @a
+
+; CHECK: @test18
+; CHECK-NEXT: ret i32 60
+define i32 @test18() {
+  %bc = bitcast [60 x i8]* @globalalias to i8*
+  %1 = call i32 @llvm.objectsize.i32(i8* %bc, i1 false)
+  ret i32 %1
+}
+
+@globalalias2 = alias weak [60 x i8]* @a
+
+; CHECK: @test19
+; CHECK: llvm.objectsize
+define i32 @test19() {
+  %bc = bitcast [60 x i8]* @globalalias2 to i8*
+  %1 = call i32 @llvm.objectsize.i32(i8* %bc, i1 false)
+  ret i32 %1
+}