From 77217229ba1bbc92f3a53099fa91bcdaa7797da8 Mon Sep 17 00:00:00 2001
From: Jack Carter <jcarter@mips.com>
Date: Thu, 21 Feb 2013 02:09:31 +0000
Subject: [PATCH] Mips specific standalone assembler addressing mode %hi and
 %lo.

The constructs %hi() and %lo() represent the high and low 16
bits of the address.
Because the 16 bit offset field of an LW instruction is
interpreted as signed, if bit 15 of the low part is 1 then the
low part will act as a negative and 1 needs to be added to the
high part.

Contributer: Vladimir Medic


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175707 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/Mips/AsmParser/MipsAsmParser.cpp |  5 +++++
 test/MC/Mips/hilo-addressing.s              | 11 +++++++++++
 test/MC/Mips/mips_directives.s              |  5 ++---
 3 files changed, 18 insertions(+), 3 deletions(-)
 create mode 100644 test/MC/Mips/hilo-addressing.s

diff --git a/lib/Target/Mips/AsmParser/MipsAsmParser.cpp b/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
index 088589fbfb1..ade60847528 100644
--- a/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
+++ b/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
@@ -888,7 +888,12 @@ bool MipsAsmParser::parseRelocOperand(const MCExpr *&Res) {
     if (Str == "lo") {
       Val = Val & 0xffff;
     } else if (Str == "hi") {
+      int LoSign = Val & 0x8000;
       Val = (Val & 0xffff0000) >> 16;
+      //lower part is treated as signed int, so if it is negative
+      //we must add 1 to hi part to compensate
+      if (LoSign)
+        Val++;
     }
     Res = MCConstantExpr::Create(Val, getContext());
     return false;
diff --git a/test/MC/Mips/hilo-addressing.s b/test/MC/Mips/hilo-addressing.s
new file mode 100644
index 00000000000..28459c20672
--- /dev/null
+++ b/test/MC/Mips/hilo-addressing.s
@@ -0,0 +1,11 @@
+# RUN: llvm-mc -show-encoding -triple mips-unknown-unknown %s | FileCheck %s
+
+  .ent hilo_test
+     .equ    addr, 0xdeadbeef
+# CHECK: # encoding: [0x3c,0x04,0xde,0xae]
+    lui $4,%hi(addr)
+# CHECK: # encoding: [0x03,0xe0,0x00,0x08]
+    jr  $31
+# CHECK: # encoding: [0x80,0x82,0xbe,0xef]
+    lb  $2,%lo(addr)($4)
+    .end hilo_test
diff --git a/test/MC/Mips/mips_directives.s b/test/MC/Mips/mips_directives.s
index d0a3beaeeaa..65d584dfa8a 100644
--- a/test/MC/Mips/mips_directives.s
+++ b/test/MC/Mips/mips_directives.s
@@ -1,5 +1,5 @@
-# RUN: llvm-mc -triple mips-unknown-unknown %s | FileCheck %s
-#this test produces no output so there isS no FileCheck call
+# RUN: llvm-mc -show-encoding -triple mips-unknown-unknown %s | FileCheck %s
+#
 $BB0_2:
   .ent directives_test
     .frame    $sp,0,$ra
@@ -17,4 +17,3 @@ $JTI0_0:
     .set macro
     .set reorder
     .set  at=$a0
-    .end directives_test