From 61f319300122bcc6fa7358ddd8fb520763cb8cba Mon Sep 17 00:00:00 2001
From: Asiri Rathnayake <asiri.rathnayake@arm.com>
Date: Thu, 4 Dec 2014 19:34:59 +0000
Subject: [PATCH] Fix yet another unseen regression caused by r223113

r223113 added support for ARM modified immediate assembly syntax. Which
assumes all immediate operands are prefixed with a '#'. This assumption
is wrong as per the ARMARM - which recommends that all '#' characters be
treated optional. The current patch fixes this regression and adds a test
case. A follow-up patch will expand the test coverage to other instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223381 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/AsmParser/ARMAsmParser.cpp | 40 +++++++++++++++--------
 test/MC/ARM/basic-arm-instructions.s      |  6 ++++
 test/MC/ARM/ldr-pseudo-parse-errors.s     |  2 +-
 3 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 4ccadf915cc..f291fe4a4dd 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -4418,15 +4418,31 @@ ARMAsmParser::parseModImm(OperandVector &Operands) {
   MCAsmLexer &Lexer = getLexer();
   int64_t Imm1, Imm2;
 
-  if ((Parser.getTok().isNot(AsmToken::Hash) &&
-       Parser.getTok().isNot(AsmToken::Dollar))
-      || Lexer.peekTok().is(AsmToken::Colon))
+  SMLoc S = Parser.getTok().getLoc();
+
+  // 1) A mod_imm operand can appear in the place of a register name:
+  //   add r0, #mod_imm
+  //   add r0, r0, #mod_imm
+  // to correctly handle the latter, we bail out as soon as we see an
+  // identifier.
+  //
+  // 2) Similarly, we do not want to parse into complex operands:
+  //   mov r0, #mod_imm
+  //   mov r0, :lower16:(_foo)
+  if (Parser.getTok().is(AsmToken::Identifier) ||
+      Parser.getTok().is(AsmToken::Colon))
     return MatchOperand_NoMatch;
 
-  SMLoc S = Parser.getTok().getLoc();
+  // Hash (dollar) is optional as per the ARMARM
+  if (Parser.getTok().is(AsmToken::Hash) ||
+      Parser.getTok().is(AsmToken::Dollar)) {
+    // Avoid parsing into complex operands (#:)
+    if (Lexer.peekTok().is(AsmToken::Colon))
+      return MatchOperand_NoMatch;
 
-  // Eat the hash (or dollar)
-  Parser.Lex();
+    // Eat the hash (dollar)
+    Parser.Lex();
+  }
 
   SMLoc Sx1, Ex1;
   Sx1 = Parser.getTok().getLoc();
@@ -4483,12 +4499,6 @@ ARMAsmParser::parseModImm(OperandVector &Operands) {
     return MatchOperand_ParseFail;
   }
 
-  if (Lexer.peekTok().isNot(AsmToken::Hash) &&
-       Lexer.peekTok().isNot(AsmToken::Dollar)) {
-    Error(Lexer.peekTok().getLoc(), "immediate operand expected");
-    return MatchOperand_ParseFail;
-  }
-
   // Eat the comma
   Parser.Lex();
 
@@ -4496,8 +4506,10 @@ ARMAsmParser::parseModImm(OperandVector &Operands) {
   SMLoc Sx2, Ex2;
   Sx2 = Parser.getTok().getLoc();
 
-  // Eat the hash (or dollar)
-  Parser.Lex();
+  // Eat the optional hash (dollar)
+  if (Parser.getTok().is(AsmToken::Hash) ||
+      Parser.getTok().is(AsmToken::Dollar))
+    Parser.Lex();
 
   const MCExpr *Imm2Exp;
   if (getParser().parseExpression(Imm2Exp, Ex2)) {
diff --git a/test/MC/ARM/basic-arm-instructions.s b/test/MC/ARM/basic-arm-instructions.s
index 878948ae7b4..b15701f1c83 100644
--- a/test/MC/ARM/basic-arm-instructions.s
+++ b/test/MC/ARM/basic-arm-instructions.s
@@ -16,6 +16,9 @@ _func:
 @ ADC (immediate)
 @------------------------------------------------------------------------------
         adc r1, r2, #0xf
+        adc r1, r2, $0xf
+        adc r1, r2, 0xf
+        adc r1, r2, 15
         adc r7, r8, #42, #2
         adc r7, r8, #-2147483638
         adc r7, r8, #40, #2
@@ -33,6 +36,9 @@ _func:
         adcseq r1, r2, #0xf00
         adceq r1, r2, #0xf00
 
+@ CHECK: adc	r1, r2, #15             @ encoding: [0x0f,0x10,0xa2,0xe2]
+@ CHECK: adc	r1, r2, #15             @ encoding: [0x0f,0x10,0xa2,0xe2]
+@ CHECK: adc	r1, r2, #15             @ encoding: [0x0f,0x10,0xa2,0xe2]
 @ CHECK: adc	r1, r2, #15             @ encoding: [0x0f,0x10,0xa2,0xe2]
 @ CHECK: adc    r7, r8, #-2147483638    @ encoding: [0x2a,0x71,0xa8,0xe2]
 @ CHECK: adc    r7, r8, #-2147483638    @ encoding: [0x2a,0x71,0xa8,0xe2]
diff --git a/test/MC/ARM/ldr-pseudo-parse-errors.s b/test/MC/ARM/ldr-pseudo-parse-errors.s
index 2e6114d6fe0..2516239f5ee 100644
--- a/test/MC/ARM/ldr-pseudo-parse-errors.s
+++ b/test/MC/ARM/ldr-pseudo-parse-errors.s
@@ -4,7 +4,7 @@
 .text
 bar:
   mov r0, =0x101
-@ CHECK: error: unexpected token in operand
+@ CHECK: error: unknown token in expression
 @ CHECK: mov r0, =0x101
 @ CHECK:         ^
 
-- 
2.34.1