[llvm] r185575 - ARM: Prevent ARMAsmParser::shouldOmitCCOutOperand() from misidentifying certain Thumb2 add immediate T3 encodings.

[Tilmann Scheller]

Author: tilmann
Date: Wed Jul  3 15:38:01 2013
New Revision: 185575

URL: http://llvm.org/viewvc/llvm-project?rev=185575&view=rev
Log:
ARM: Prevent ARMAsmParser::shouldOmitCCOutOperand() from misidentifying certain Thumb2 add immediate T3 encodings.

Before the fix Thumb2 instructions of type "add rD, rN, #imm" (T3 encoding, see ARM ARM A8.8.4) with rD and rN both being low registers (r0-r7) were classified as having the T4 encoding.

The T4 encoding doesn't have a cc_out operand so for above instructions the operand gets erroneously removed, corrupting the token stream and leading to parse errors later in the process.

This bug prevented "add r1, r7, #0xcbcbcbcb" from being assembled correctly.

Fixes <rdar://problem/14224440>.


Modified:
    llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
    llvm/trunk/test/MC/ARM/basic-thumb2-instructions.s

Modified: llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp?rev=185575&r1=185574&r2=185575&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp (original)
+++ llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp Wed Jul  3 15:38:01 2013
@@ -5076,15 +5076,6 @@ bool ARMAsmParser::shouldOmitCCOutOperan
       static_cast<ARMOperand*>(Operands[5])->isImm()) {
     // Nest conditions rather than one big 'if' statement for readability.
     //
-    // If either register is a high reg, it's either one of the SP
-    // variants (handled above) or a 32-bit encoding, so we just
-    // check against T3. If the second register is the PC, this is an
-    // alternate form of ADR, which uses encoding T4, so check for that too.
-    if ((!isARMLowRegister(static_cast<ARMOperand*>(Operands[3])->getReg()) ||
-         !isARMLowRegister(static_cast<ARMOperand*>(Operands[4])->getReg())) &&
-        static_cast<ARMOperand*>(Operands[4])->getReg() != ARM::PC &&
-        static_cast<ARMOperand*>(Operands[5])->isT2SOImm())
-      return false;
     // If both registers are low, we're in an IT block, and the immediate is
     // in range, we should use encoding T1 instead, which has a cc_out.
     if (inITBlock() &&
@@ -5092,6 +5083,11 @@ bool ARMAsmParser::shouldOmitCCOutOperan
         isARMLowRegister(static_cast<ARMOperand*>(Operands[4])->getReg()) &&
         static_cast<ARMOperand*>(Operands[5])->isImm0_7())
       return false;
+    // Check against T3. If the second register is the PC, this is an
+    // alternate form of ADR, which uses encoding T4, so check for that too.
+    if (static_cast<ARMOperand*>(Operands[4])->getReg() != ARM::PC &&
+        static_cast<ARMOperand*>(Operands[5])->isT2SOImm())
+      return false;
 
     // Otherwise, we use encoding T4, which does not have a cc_out
     // operand.

Modified: llvm/trunk/test/MC/ARM/basic-thumb2-instructions.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ARM/basic-thumb2-instructions.s?rev=185575&r1=185574&r2=185575&view=diff
==============================================================================
--- llvm/trunk/test/MC/ARM/basic-thumb2-instructions.s (original)
+++ llvm/trunk/test/MC/ARM/basic-thumb2-instructions.s Wed Jul  3 15:38:01 2013
@@ -79,6 +79,7 @@ _func:
         add r0, r0, #32
         adds r2, r2, #56
         adds r2, #56
+        add r1, r7, #0xcbcbcbcb
 
         adds.w r2, #-16
         adds.w r2, r2, #-16
@@ -101,6 +102,7 @@ _func:
 @ CHECK: add.w	r0, r0, #32             @ encoding: [0x00,0xf1,0x20,0x00]
 @ CHECK: adds	r2, #56                 @ encoding: [0x38,0x32]
 @ CHECK: adds	r2, #56                 @ encoding: [0x38,0x32]
+@ CHECK: add.w  r1, r7, #3419130827     @ encoding: [0x07,0xf1,0xcb,0x31]
 
 @ CHECK: subs.w	r2, r2, #16             @ encoding: [0xb2,0xf1,0x10,0x02]
 @ CHECK: subs.w	r2, r2, #16             @ encoding: [0xb2,0xf1,0x10,0x02]