Allow later -z name=<int> args to override earlier args

Summary:
lld already gives later -z options precedence in getZFlag().

This matches the behavior of ld.bfd and ld.gold, where later options
override earlier ones. (I tested with -z max-page-size and -z stack-size.)

Reviewers: ruiu, espindola, grimar

Reviewed By: ruiu, grimar

Subscribers: grimar, emaste, arichardson, llvm-commits

Differential Revision: https://reviews.llvm.org/D52526

llvm-svn: 343145

lld/Common/Args.cpp

@@ -41,7 +41,7 @@ std::vector<StringRef> lld::args::getStrings(opt::InputArgList &Args, int Id) {
 
 uint64_t lld::args::getZOptionValue(opt::InputArgList &Args, int Id,
                                     StringRef Key, uint64_t Default) {
-  for (auto *Arg : Args.filtered(Id)) {
+  for (auto *Arg : Args.filtered_reverse(Id)) {
     std::pair<StringRef, StringRef> KV = StringRef(Arg->getValue()).split('=');
     if (KV.first == Key) {
       uint64_t Result = Default;

lld/test/ELF/zstack-size.s

@@ -6,6 +6,9 @@
 # RUN: ld.lld -z stack-size=0 %t -o %t2
 # RUN: llvm-readobj -program-headers %t2 | FileCheck %s -check-prefix=CHECK2
 
+# RUN: ld.lld -z stack-size=0x2000 -z stack-size=0x1000 %t -o %t3
+# RUN: llvm-readobj -program-headers %t3 | FileCheck %s -check-prefix=CHECK1
+
 .global _start
 _start:
   nop