ARM assembly aliases for add negative immediates using sub.

'add r2, #-1024' should just use 'sub r2, #1024' rather than erroring out.
Thumb1 aliases for adding a negative immediate to the stack pointer,
also.

rdar://11192734

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154123 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 38 insertions, 0 deletions

diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index a558a61592..e9164bcfa8 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -579,6 +579,14 @@ public:
     int64_t Value = CE->getValue();
     return ((Value & 3) == 0) && Value >= 0 && Value <= 508;
   }
+  bool isImm0_508s4Neg() const {
+    if (!isImm()) return false;
+    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
+    if (!CE) return false;
+    int64_t Value = -CE->getValue();
+    // explicitly exclude zero. we want that to use the normal 0_508 version.
+    return ((Value & 3) == 0) && Value > 0 && Value <= 508;
+  }
   bool isImm0_255() const {
     if (!isImm()) return false;
     const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
@@ -586,6 +594,20 @@ public:
     int64_t Value = CE->getValue();
     return Value >= 0 && Value < 256;
   }
+  bool isImm0_4095() const {
+    if (!isImm()) return false;
+    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
+    if (!CE) return false;
+    int64_t Value = CE->getValue();
+    return Value >= 0 && Value < 4096;
+  }
+  bool isImm0_4095Neg() const {
+    if (!isImm()) return false;
+    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
+    if (!CE) return false;
+    int64_t Value = -CE->getValue();
+    return Value > 0 && Value < 4096;
+  }
   bool isImm0_1() const {
     if (!isImm()) return false;
     const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
@@ -1499,6 +1521,14 @@ public:
     Inst.addOperand(MCOperand::CreateImm(CE->getValue() / 4));
   }
 
+  void addImm0_508s4NegOperands(MCInst &Inst, unsigned N) const {
+    assert(N == 1 && "Invalid number of operands!");
+    // The immediate is scaled by four in the encoding and is stored
+    // in the MCInst as such. Lop off the low two bits here.
+    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
+    Inst.addOperand(MCOperand::CreateImm(-(CE->getValue() / 4)));
+  }
+
   void addImm0_508s4Operands(MCInst &Inst, unsigned N) const {
     assert(N == 1 && "Invalid number of operands!");
     // The immediate is scaled by four in the encoding and is stored
@@ -1557,6 +1587,14 @@ public:
     Inst.addOperand(MCOperand::CreateImm(-CE->getValue()));
   }
 
+  void addImm0_4095NegOperands(MCInst &Inst, unsigned N) const {
+    assert(N == 1 && "Invalid number of operands!");
+    // The operand is actually an imm0_4095, but we have its
+    // negation in the assembly source, so twiddle it here.
+    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
+    Inst.addOperand(MCOperand::CreateImm(-CE->getValue()));
+  }
+
   void addARMSOImmNotOperands(MCInst &Inst, unsigned N) const {
     assert(N == 1 && "Invalid number of operands!");
     // The operand is actually a so_imm, but we have its bitwise