[lld] r351916 - MemoryBlock: Do not automatically extend a given size to a multiple of page size.

[Rui Ueyama via llvm-commits]

Author: ruiu
Date: Tue Jan 22 18:03:26 2019
New Revision: 351916

URL: http://llvm.org/viewvc/llvm-project?rev=351916&view=rev
Log:
MemoryBlock: Do not automatically extend a given size to a multiple of page size.

Previously, MemoryBlock automatically extends a requested buffer size to a
multiple of page size because (I believe) doing it was thought to be harmless
and with that you could get more memory (on average 2KiB on 4KiB-page systems)
"for free".

That programming interface turned out to be error-prone. If you request N
bytes, you usually expect that a resulting object returns N for `size()`.
That's not the case for MemoryBlock.

Looks like there is only one place where we take the advantage of
allocating more memory than the requested size. So, with this patch, I
simply removed the automatic size expansion feature from MemoryBlock
and do it on the caller side when needed. MemoryBlock now always
returns a buffer whose size is equal to the requested size.

Differential Revision: https://reviews.llvm.org/D56941

Modified:
    lld/trunk/test/ELF/stdout.s

Modified: lld/trunk/test/ELF/stdout.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/stdout.s?rev=351916&r1=351915&r2=351916&view=diff
==============================================================================
--- lld/trunk/test/ELF/stdout.s (original)
+++ lld/trunk/test/ELF/stdout.s Tue Jan 22 18:03:26 2019
@@ -1,12 +1,15 @@
 # REQUIRES: x86
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
-# RUN: ld.lld %t.o -o - > %t
-# RUN: llvm-objdump -d %t | FileCheck %s
+# RUN: ld.lld %t.o -o - > %t1
+# RUN: llvm-objdump -d %t1 | FileCheck %s
 
 # CHECK: 0000000000201000 _start:
 # CHECK: 201000: 90 nop
 
+# RUN: ld.lld %t.o -o %t2
+# RUN: diff %t1 %t2
+
 .globl _start
 _start:
   nop