Merging r195769:

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r195769 | dyatkovskiy | 2013-11-26 08:11:03 -0800 (Tue, 26 Nov 2013) | 27 lines

PR17925 bugfix.

Short description.

This issue is about case of treating pointers as integers.
We treat pointers as different if they references different address space.
At the same time, we treat pointers equal to integers (with machine address
width). It was a point of false-positive. Consider next case on 32bit machine:

void foo0(i32 addrespace(1)* %p)
void foo1(i32 addrespace(2)* %p)
void foo2(i32 %p)

foo0 != foo1, while
foo1 == foo2 and foo0 == foo2.

As you can see it breaks transitivity. That means that result depends on order
of how functions are presented in module. Next order causes merging of foo0
and foo1: foo2, foo0, foo1
First foo0 will be merged with foo2, foo0 will be erased. Second foo1 will be
merged with foo2.
Depending on order, things could be merged we don't expect to.

The fix:
Forbid to treat any pointer as integer, except for those, who belong to address space 0.


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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_34@195810 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 11 deletions

diff --git a/lib/Transforms/IPO/MergeFunctions.cpp b/lib/Transforms/IPO/MergeFunctions.cpp
index b8397d6..3861421 100644
--- a/lib/Transforms/IPO/MergeFunctions.cpp
+++ b/lib/Transforms/IPO/MergeFunctions.cpp
@@ -210,19 +210,20 @@ private:
 // Any two pointers in the same address space are equivalent, intptr_t and
 // pointers are equivalent. Otherwise, standard type equivalence rules apply.
 bool FunctionComparator::isEquivalentType(Type *Ty1, Type *Ty2) const {
+
+  PointerType *PTy1 = dyn_cast<PointerType>(Ty1);
+  PointerType *PTy2 = dyn_cast<PointerType>(Ty2);
+
+  if (TD) {
+    if (PTy1 && PTy1->getAddressSpace() == 0) Ty1 = TD->getIntPtrType(Ty1);
+    if (PTy2 && PTy2->getAddressSpace() == 0) Ty2 = TD->getIntPtrType(Ty2);
+  }
+
   if (Ty1 == Ty2)
     return true;
-  if (Ty1->getTypeID() != Ty2->getTypeID()) {
-    if (TD) {
-
-      if (isa<PointerType>(Ty1) && Ty2 == TD->getIntPtrType(Ty1))
-        return true;
 
-      if (isa<PointerType>(Ty2) && Ty1 == TD->getIntPtrType(Ty2))
-        return true;
-    }
+  if (Ty1->getTypeID() != Ty2->getTypeID())
     return false;
-  }
 
   switch (Ty1->getTypeID()) {
   default:
@@ -244,8 +245,7 @@ bool FunctionComparator::isEquivalentType(Type *Ty1, Type *Ty2) const {
     return true;
 
   case Type::PointerTyID: {
-    PointerType *PTy1 = cast<PointerType>(Ty1);
-    PointerType *PTy2 = cast<PointerType>(Ty2);
+    assert(PTy1 && PTy2 && "Both types must be pointers here.");
     return PTy1->getAddressSpace() == PTy2->getAddressSpace();
   }