From 3527e5fcb374ae48128a96935387490908a06b97 Mon Sep 17 00:00:00 2001
From: Daniel Sanders <daniel.sanders@imgtec.com>
Date: Tue, 25 Mar 2014 13:01:06 +0000
Subject: [PATCH] [mips] '.set at=$0' should be equivalent to '.set noat'

Differential Revision: http://llvm-reviews.chandlerc.com/D3171

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204714 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/Mips/AsmParser/MipsAsmParser.cpp |  2 +-
 test/MC/Mips/mips-noat.s                    | 15 +++++++++++----
 test/MC/Mips/set-at-directive-explicit-at.s |  3 +++
 3 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/lib/Target/Mips/AsmParser/MipsAsmParser.cpp b/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
index 74e19c5be33..078b554e2e0 100644
--- a/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
+++ b/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
@@ -2352,7 +2352,7 @@ bool MipsAsmParser::parseSetAtDirective() {
       return false;
     }
 
-    if (AtRegNo < 1 || AtRegNo > 31) {
+    if (AtRegNo < 0 || AtRegNo > 31) {
       reportParseError("unexpected token in statement");
       return false;
     }
diff --git a/test/MC/Mips/mips-noat.s b/test/MC/Mips/mips-noat.s
index 152a1ee4067..b83c5178077 100644
--- a/test/MC/Mips/mips-noat.s
+++ b/test/MC/Mips/mips-noat.s
@@ -1,7 +1,8 @@
 # RUN: not llvm-mc %s -triple=mips-unknown-linux 2>%t0 | FileCheck %s
 # RUN: FileCheck -check-prefix=ERROR %s < %t0
+# Check that using the assembler temporary when .set noat is in effect is an error.
 
-# We start with $at enabled
+# We start with the assembler temporary enabled
 # CHECK-LABEL: test1:
 # CHECK:  lui   $1, 1
 # CHECK:  addu  $1, $1, $2
@@ -9,10 +10,8 @@
 test1:
         lw      $2, 65536($2)
 
-# Check that using $at when .set noat is in effect is an error.
 # FIXME: It would be better if the error pointed at the mnemonic instead of the newline
-# ERROR: mips-noat.s:[[@LINE+5]]:1: error: Pseudo instruction requires $at, which is not available
-# ERROR-NOT: error
+# ERROR: mips-noat.s:[[@LINE+4]]:1: error: Pseudo instruction requires $at, which is not available
 test2:
         .set noat
         lw      $2, 65536($2)
@@ -25,3 +24,11 @@ test2:
 test3:
         .set at
         lw      $2, 65536($2)
+
+# FIXME: It would be better if the error pointed at the mnemonic instead of the newline
+# ERROR: mips-noat.s:[[@LINE+4]]:1: error: Pseudo instruction requires $at, which is not available
+test4:
+        .set at=$0
+        lw      $2, 65536($2)
+
+# ERROR-NOT: error
diff --git a/test/MC/Mips/set-at-directive-explicit-at.s b/test/MC/Mips/set-at-directive-explicit-at.s
index b8c8adc8818..71f1a98fae4 100644
--- a/test/MC/Mips/set-at-directive-explicit-at.s
+++ b/test/MC/Mips/set-at-directive-explicit-at.s
@@ -26,6 +26,9 @@ foo:
 # CHECK:   jr    $1                      # encoding: [0x08,0x00,0x20,0x00]
     .set noat
     jr    $at
+# CHECK:   jr    $1                      # encoding: [0x08,0x00,0x20,0x00]
+    .set at=$0
+    jr    $at
 
 # CHECK:   jr    $16                     # encoding: [0x08,0x00,0x00,0x02]
 # WARNINGS: :[[@LINE+2]]:12: warning: Used $16 with ".set at=$16"