From 7731c957a643504636135df4e8339d35caa9bf59 Mon Sep 17 00:00:00 2001
From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Sat, 16 Feb 2013 15:00:16 +0000
Subject: [PATCH] MCParser: Reject .balign with non-pow2 alignments.

GNU as rejects them and there are configure scripts in the wild that check if
the assembler rejects ".align 3" to determine whether the alignment is in bytes
or powers of two.

llvm-svn: 175360
---
 lib/MC/MCParser/AsmParser.cpp     |  4 ++++
 test/MC/AsmParser/align_invalid.s | 10 ++++++++++
 2 files changed, 14 insertions(+)
 create mode 100644 test/MC/AsmParser/align_invalid.s

diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index b7953c1a597..9c998ff796c 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -2456,6 +2456,10 @@ bool AsmParser::ParseDirectiveAlign(bool IsPow2, unsigned ValueSize) {
     }
 
     Alignment = 1ULL << Alignment;
+  } else {
+    // Reject alignments that aren't a power of two, for gas compatibility.
+    if (!isPowerOf2_64(Alignment))
+      Error(AlignmentLoc, "alignment must be a power of 2");
   }
 
   // Diagnose non-sensical max bytes to align.
diff --git a/test/MC/AsmParser/align_invalid.s b/test/MC/AsmParser/align_invalid.s
new file mode 100644
index 00000000000..0d06d9423ce
--- /dev/null
+++ b/test/MC/AsmParser/align_invalid.s
@@ -0,0 +1,10 @@
+# RUN: llvm-mc -triple i386-linux-gnu < %s 2>&1 | FileCheck %s -check-prefix=ELF
+# RUN: llvm-mc -triple i386-apple-darwin < %s 2>&1 | FileCheck %s -check-prefix=DARWIN
+
+.align 3
+# ELF: error: alignment must be a power of 2
+# DARWIN-NOT: error
+
+.align 32
+# ELF-NOT: error
+# DARWIN: error: invalid alignment value