ARM assembly 'cmp lr, #0' should not encode using 'cmn'.

The CMP->CMN alias was matching for an immediate of zero when it
should only match for negative values.

rdar://11129224

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153689 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 911eb132e5..e0022064ba 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -782,7 +782,8 @@ public:
     const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
     if (!CE) return false;
     int64_t Value = CE->getValue();
-    return ARM_AM::getSOImmVal(-Value) != -1;
+    // Negation must be representable as an so_imm and be non-zero.
+    return Value && ARM_AM::getSOImmVal(-Value) != -1;
   }
   bool isT2SOImm() const {
     if (!isImm()) return false;
@@ -803,7 +804,8 @@ public:
     const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
     if (!CE) return false;
     int64_t Value = CE->getValue();
-    return ARM_AM::getT2SOImmVal(-Value) != -1;
+    // Negation must be representable as a t2_so_imm and be non-zero.
+    return Value && ARM_AM::getT2SOImmVal(-Value) != -1;
   }
   bool isSetEndImm() const {
     if (!isImm()) return false;