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>.

llvm-svn: 185575

1 files changed, 5 insertions, 9 deletions

diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index c270ed034b2..bd4ea535567 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -5076,15 +5076,6 @@ bool ARMAsmParser::shouldOmitCCOutOperand(StringRef Mnemonic,
       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::shouldOmitCCOutOperand(StringRef Mnemonic,
         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.