From f54df2f626930486b696a8e32465c7ed79391e12 Mon Sep 17 00:00:00 2001
From: Sanjoy Das <sanjoy@playingwithpointers.com>
Date: Sat, 17 Jun 2017 20:28:13 +0000
Subject: [PATCH] [SROA] Add support for non-integral pointers

Summary: C.f. http://llvm.org/docs/LangRef.html#non-integral-pointer-type

Reviewers: chandlerc, loladiro

Reviewed By: loladiro

Subscribers: reames, loladiro, mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D32203

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305639 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/SROA.cpp                | 13 +++++-
 test/Transforms/SROA/non-integral-pointers.ll | 46 +++++++++++++++++++
 2 files changed, 57 insertions(+), 2 deletions(-)
 create mode 100644 test/Transforms/SROA/non-integral-pointers.ll

diff --git a/lib/Transforms/Scalar/SROA.cpp b/lib/Transforms/Scalar/SROA.cpp
index 1527f15f18a..f32d2d58229 100644
--- a/lib/Transforms/Scalar/SROA.cpp
+++ b/lib/Transforms/Scalar/SROA.cpp
@@ -1637,8 +1637,17 @@ static bool canConvertValue(const DataLayout &DL, Type *OldTy, Type *NewTy) {
       return cast<PointerType>(NewTy)->getPointerAddressSpace() ==
         cast<PointerType>(OldTy)->getPointerAddressSpace();
     }
-    if (NewTy->isIntegerTy() || OldTy->isIntegerTy())
-      return true;
+
+    // We can convert integers to integral pointers, but not to non-integral
+    // pointers.
+    if (OldTy->isIntegerTy())
+      return !DL.isNonIntegralPointerType(NewTy);
+
+    // We can convert integral pointers to integers, but non-integral pointers
+    // need to remain pointers.
+    if (!DL.isNonIntegralPointerType(OldTy))
+      return NewTy->isIntegerTy();
+
     return false;
   }
 
diff --git a/test/Transforms/SROA/non-integral-pointers.ll b/test/Transforms/SROA/non-integral-pointers.ll
new file mode 100644
index 00000000000..63286309f6f
--- /dev/null
+++ b/test/Transforms/SROA/non-integral-pointers.ll
@@ -0,0 +1,46 @@
+; RUN: opt -sroa -S < %s | FileCheck %s
+
+; This test checks that SROA does not introduce ptrtoint and inttoptr
+; casts from and to non-integral pointers.  The "ni:4" bit in the
+; datalayout states that pointers of address space 4 are to be
+; considered "non-integral".
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128-ni:4"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @f0(i1 %alwaysFalse, i64 %val) {
+; CHECK-LABEL: @f0(
+; CHECK-NOT: inttoptr
+; CHECK-NOT: ptrtoint
+entry:
+  %loc = alloca i64
+  store i64 %val, i64* %loc
+  br i1 %alwaysFalse, label %neverTaken, label %alwaysTaken
+
+neverTaken:
+  %loc.bc = bitcast i64* %loc to i8 addrspace(4)**
+  %ptr = load i8 addrspace(4)*, i8 addrspace(4)** %loc.bc
+  store i8 5, i8 addrspace(4)* %ptr
+  ret void
+
+alwaysTaken:
+  ret void
+}
+
+define i64 @f1(i1 %alwaysFalse, i8 addrspace(4)* %val) {
+; CHECK-LABEL: @f1(
+; CHECK-NOT: inttoptr
+; CHECK-NOT: ptrtoint
+entry:
+  %loc = alloca i8 addrspace(4)*
+  store i8 addrspace(4)* %val, i8 addrspace(4)** %loc
+  br i1 %alwaysFalse, label %neverTaken, label %alwaysTaken
+
+neverTaken:
+  %loc.bc = bitcast i8 addrspace(4)** %loc to i64*
+  %int = load i64, i64* %loc.bc
+  ret i64 %int
+
+alwaysTaken:
+  ret i64 42
+}
-- 
2.40.0