ARM: Only enforce 4-byte alignment on Thumb-2 functions with constant pools.

This appears to have been introduced back in r76698 as part of an unrelated
change. I can find no official ARM documentation stating that Thumb-2 functions
require 4-byte alignment; in fact, ARM documentation appears to contradict
this (see, e.g., ARM Architecture Reference Manual Thumb-2 Supplement,
section 2.6.1: "Thumb-2 enforces 16-bit alignment on all instructions.").

Also remove code that sets alignment for ARM functions, which is redundant
with code in the MachineFunction constructor, and remove the hidden
-arm-align-constant-islands flag, which has been enabled by default since
r146739 (Dec 2011) and has probably received sufficient testing by now.

Differential Revision: http://reviews.llvm.org/D9138

llvm-svn: 235636

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/ARM/thumb-alignment.ll b/llvm/test/CodeGen/ARM/thumb-alignment.ll
new file mode 100644
index 00000000000..d2565098798
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/thumb-alignment.ll
@@ -0,0 +1,15 @@
+; RUN: llc -relocation-model=pic -mtriple=thumbv7-unknown-linux -o - %s | FileCheck %s
+
+@x = external global i32
+
+; CHECK: .globl	foo
+; CHECK-NEXT: .align	2
+define i32* @foo() {
+  ret i32* @x
+}
+
+; CHECK: .globl	bar
+; CHECK-NEXT: .align	1
+define i32* @bar() {
+  ret i32* zeroinitializer
+}