From dfdb731967d8427f09a90110985b0f71a670b3d9 Mon Sep 17 00:00:00 2001
From: Serge Pavlov <sepavloff@gmail.com>
Date: Tue, 16 Jul 2013 07:14:18 +0000
Subject: [PATCH] Limit number of bits in size representation so that bit size
 fit 64 bits. This fixes PR8256 and some others.

llvm-svn: 186385
---
 clang/lib/AST/Type.cpp          | 11 ++++++-----
 clang/test/Sema/array-size-64.c |  9 +++++++--
 clang/test/Sema/offsetof-64.c   |  2 +-
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
index af4ea09..4068b2b 100644
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -111,11 +111,12 @@ unsigned ConstantArrayType::getNumAddressingBits(ASTContext &Context,
 unsigned ConstantArrayType::getMaxSizeBits(ASTContext &Context) {
   unsigned Bits = Context.getTypeSize(Context.getSizeType());
   
-  // GCC appears to only allow 63 bits worth of address space when compiling
-  // for 64-bit, so we do the same.
-  if (Bits == 64)
-    --Bits;
-  
+  // Limit the number of bits in size_t so that maximal bit size fits 64 bit
+  // integer (see PR8256).  We can do this as currently there is no hardware
+  // that supports full 64-bit virtual space.
+  if (Bits > 61)
+    Bits = 61;
+
   return Bits;
 }
 
diff --git a/clang/test/Sema/array-size-64.c b/clang/test/Sema/array-size-64.c
index f22e8e7..0e094bfa 100644
--- a/clang/test/Sema/array-size-64.c
+++ b/clang/test/Sema/array-size-64.c
@@ -2,6 +2,11 @@
 
 void f() {
   int a[2147483647U][2147483647U]; // expected-error{{array is too large}}
-  int b[1073741825U - 1U][2147483647U];
-  int c[18446744073709551615U/sizeof(int)/2];
+  int b[1073741825U - 1U][2147483647U]; // expected-error{{array is too large}}
 }
+
+void pr8256 () {
+  typedef char a[1LL<<61];  // expected-error {{array is too large}}
+  typedef char b[(long long)sizeof(a)-1];
+}
+
diff --git a/clang/test/Sema/offsetof-64.c b/clang/test/Sema/offsetof-64.c
index fb3d6e9..4a80dee 100644
--- a/clang/test/Sema/offsetof-64.c
+++ b/clang/test/Sema/offsetof-64.c
@@ -2,7 +2,7 @@
 
 // PR15216
 // Don't crash when taking computing the offset of structs with large arrays.
-const unsigned long Size = (1l << 62);
+const unsigned long Size = (1l << 60);
 
 struct Chunk1 {
   char padding[Size];
-- 
2.7.4