[tools] [llvm-nm] Default to reading from stdin not a.out
Summary: This moves away from defaulting to a.out and uses stdin only if stdin has a file redirected to it. This has been discussed on the llvm-dev mailing list [[ https://lists.llvm.org/pipermail/llvm-dev/2019-July/133642.html | here ]].
Reviewers: jhenderson, rupprecht, MaskRay, chrisjackson
Reviewed By: jhenderson, MaskRay
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64290
llvm-svn: 365889
diff --git a/llvm/docs/CommandGuide/llvm-nm.rst b/llvm/docs/CommandGuide/llvm-nm.rst
index e3b3658..3b7ea93 100644
--- a/llvm/docs/CommandGuide/llvm-nm.rst
+++ b/llvm/docs/CommandGuide/llvm-nm.rst
@@ -13,9 +13,8 @@
The :program:`llvm-nm` utility lists the names of symbols from LLVM bitcode
files, object files, and archives. Each symbol is listed along with some simple
-information about its provenance. If no filename is specified, *a.out* is used
-as the input. If *-* is used as a filename, :program:`llvm-nm` will read a file
-from its standard input stream.
+information about its provenance. If no filename is specified, or *-* is used as
+a filename, :program:`llvm-nm` will read a file from its standard input stream.
:program:`llvm-nm`'s default output format is the traditional BSD :program:`nm`
output format. Each such output record consists of an (optional) 8-digit
diff --git a/llvm/test/tools/llvm-nm/stdin.test b/llvm/test/tools/llvm-nm/stdin.test
new file mode 100644
index 0000000..352ee23
--- /dev/null
+++ b/llvm/test/tools/llvm-nm/stdin.test
@@ -0,0 +1,33 @@
+## Test llvm-nm when using stdin both explicitly (using '-' as a filename)
+## and implicitly (not specifying any filename).
+
+# RUN: yaml2obj %s -o %t.o
+
+## Pass an explicit filename to produce a baseline output. llvm-nm should
+## have the same behavior when opening a file itself and when reading that
+## file from its standard input stream.
+# RUN: llvm-nm %t.o > %t.base 2> %t.err
+
+## Make sure there is no warning message about no file redirected to stdin.
+# RUN: FileCheck %s --input-file=%t.err --allow-empty --implicit-check-not={{.}}
+
+# RUN: llvm-nm - < %t.o > %t.explicit 2> %t.err
+# RUN: FileCheck %s --input-file=%t.err --allow-empty --implicit-check-not={{.}}
+# RUN: cmp %t.base %t.explicit
+
+# RUN: llvm-nm < %t.o > %t.implicit 2> %t.err
+# RUN: FileCheck %s --input-file=%t.err --allow-empty --implicit-check-not={{.}}
+# RUN: cmp %t.base %t.implicit
+
+!ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_REL
+ Machine: EM_X86_64
+Sections:
+ - Name: .text
+ Type: SHT_PROGBITS
+Symbols:
+ - Name: symbol_a
+ Section: .text
diff --git a/llvm/tools/llvm-nm/llvm-nm.cpp b/llvm/tools/llvm-nm/llvm-nm.cpp
index aa62e6f..c45c871 100644
--- a/llvm/tools/llvm-nm/llvm-nm.cpp
+++ b/llvm/tools/llvm-nm/llvm-nm.cpp
@@ -34,6 +34,7 @@
#include "llvm/Support/Format.h"
#include "llvm/Support/InitLLVM.h"
#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Process.h"
#include "llvm/Support/Program.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/TargetSelect.h"
@@ -1751,6 +1752,12 @@
}
static void dumpSymbolNamesFromFile(std::string &Filename) {
+ if (Filename == "-" && sys::Process::StandardInIsUserInput()) {
+ WithColor::warning(errs(), ToolName) << "can't read from terminal\n";
+ cl::PrintHelpMessage();
+ HadError = true;
+ return;
+ }
ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
MemoryBuffer::getFileOrSTDIN(Filename);
if (error(BufferOrErr.getError(), Filename))
@@ -2082,7 +2089,7 @@
if (OutputFormat == sysv || SizeSort)
PrintSize = true;
if (InputFilenames.empty())
- InputFilenames.push_back("a.out");
+ InputFilenames.push_back("-");
if (InputFilenames.size() > 1)
MultipleFiles = true;