From 8f57233536c0ae7efbe8bb5b800044f6d134db2a Mon Sep 17 00:00:00 2001
From: Saleem Abdulrasool <compnerd@compnerd.org>
Date: Mon, 23 Dec 2013 17:23:58 +0000
Subject: [PATCH] ARM: bkpt has an implicit immediate constant 0

The bkpt mnemonic has an implicit immediate constant of 0 unless otherwise
specified.  Add an instruction alias for the unvalued breakpoint mnemonic to
treat it as a 0.  This improves compatibility with GNU AS.

Signed-off-by: Saleem Abdulrasool <compnerd@compnerd.org>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197913 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMInstrInfo.td  |  2 ++
 lib/Target/ARM/ARMInstrThumb.td |  2 ++
 test/MC/ARM/bkpt.s              | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 36 insertions(+)
 create mode 100644 test/MC/ARM/bkpt.s

diff --git a/lib/Target/ARM/ARMInstrInfo.td b/lib/Target/ARM/ARMInstrInfo.td
index ad500eacad0..e778bc8f4fa 100644
--- a/lib/Target/ARM/ARMInstrInfo.td
+++ b/lib/Target/ARM/ARMInstrInfo.td
@@ -1725,6 +1725,8 @@ def BKPT : AInoP<(outs), (ins imm0_65535:$val), MiscFrm, NoItinerary,
   let Inst{31-28} = 0xe; // AL
   let Inst{7-4} = 0b0111;
 }
+// default immediate for breakpoint mnemonic
+def : InstAlias<"bkpt", (BKPT 0)>, Requires<[IsARM]>;
 
 def HLT : AInoP<(outs), (ins imm0_65535:$val), MiscFrm, NoItinerary,
                  "hlt", "\t$val", []>, Requires<[IsARM, HasV8]> {
diff --git a/lib/Target/ARM/ARMInstrThumb.td b/lib/Target/ARM/ARMInstrThumb.td
index 250b3c6f2c6..f6d233a39c5 100644
--- a/lib/Target/ARM/ARMInstrThumb.td
+++ b/lib/Target/ARM/ARMInstrThumb.td
@@ -300,6 +300,8 @@ def tBKPT : T1I<(outs), (ins imm0_255:$val), NoItinerary, "bkpt\t$val",
   bits<8> val;
   let Inst{7-0} = val;
 }
+// default immediate for breakpoint mnemonic
+def : InstAlias<"bkpt", (tBKPT 0)>, Requires<[IsThumb]>;
 
 def tHLT : T1I<(outs), (ins imm0_63:$val), NoItinerary, "hlt\t$val",
                 []>, T1Encoding<0b101110>, Requires<[IsThumb, HasV8]> {
diff --git a/test/MC/ARM/bkpt.s b/test/MC/ARM/bkpt.s
new file mode 100644
index 00000000000..fcd4040b186
--- /dev/null
+++ b/test/MC/ARM/bkpt.s
@@ -0,0 +1,32 @@
+@ RUN: llvm-mc -triple armv7-unknown-unknown -filetype asm -o - %s | FileCheck %s
+
+	.syntax unified
+	.thumb
+
+	.global thumb_default_bkpt
+	.type thumb_default_bkpt, %function
+	.thumb_func
+thumb_default_bkpt:
+	bkpt
+
+@ CHECK-LABEL: thumb_default_bkpt
+@ CHECK: bkpt #0
+
+	.global normal_bkpt
+	.type normal_bkpt, %function
+normal_bkpt:
+	bkpt #42
+
+@ CHECK-LABEL: normal_bkpt
+@ CHECK: bkpt #42
+
+	.arm
+
+	.global arm_default_bkpt
+	.type arm_default_bkpt, %function
+arm_default_bkpt:
+	bkpt
+
+@ CEHCK-LABEL: arm_default_bkpt
+@ CHECK: bkpt #0
+