From: Scott Douglass <sdouglass@arm.com>
Date: Thu, 9 Jul 2015 14:13:48 +0000 (+0000)
Subject: [ARM] Don't be overzealous converting Thumb1 3 to 2 operands
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=7b8defda793c0f22fdccb98232d0ae5230453d6f;p=oota-llvm.git

[ARM] Don't be overzealous converting Thumb1 3 to 2 operands

Differential Revision: http://reviews.llvm.org/D11056

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241801 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index cea7070abd0..0ae6925c28b 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -5512,6 +5512,11 @@ void ARMAsmParser::tryConvertingToTwoOperandForm(StringRef Mnemonic,
     if (((Mnemonic == "add" && CarrySetting) || Mnemonic == "sub") &&
         Op5.isReg())
       Transform = false;
+
+    // Don't transform 'add/sub{s} Rd, Rd, #imm' if the immediate fits into
+    // 3-bits because the ARMARM says not to.
+    if ((Mnemonic == "add" || Mnemonic == "sub") && Op5.isImm0_7())
+      Transform = false;
   }
 
   if (Transform)
diff --git a/test/MC/ARM/thumb_rewrites.s b/test/MC/ARM/thumb_rewrites.s
index ed712156213..b2ef83d4936 100644
--- a/test/MC/ARM/thumb_rewrites.s
+++ b/test/MC/ARM/thumb_rewrites.s
@@ -1,5 +1,11 @@
 @ RUN: llvm-mc -triple thumbv6m -show-encoding < %s | FileCheck %s
 
+    adds    r1, r1, #3
+@ CHECK: adds   r1, r1, #3          @ encoding: [0xc9,0x1c]
+
+    adds    r1, #3
+@ CHECK: adds   r1, #3              @ encoding: [0x03,0x31]
+
     adds    r0, r0, #8
 @ CHECK: adds   r0, #8              @ encoding: [0x08,0x30]
 
@@ -34,6 +40,12 @@
     subs    r0, r0, r0
 @ CHECK: subs   r0, r0, r0          @ encoding: [0x00,0x1a]
 
+    subs    r3, r3, #5
+@ CHECK: subs   r3, r3, #5          @ encoding: [0x5b,0x1f]
+
+    subs    r3, #5
+@ CHECK: subs   r3, #5              @ encoding: [0x05,0x3b]
+
     subs    r2, r2, #8
 @ CHECK: subs   r2, #8              @ encoding: [0x08,0x3a]