Add Thumb2 alias for "mov Rd, #imm" to "mvn Rd, #~imm".

When '~imm' is encodable as a t2_so_imm but plain 'imm' is not. For example,
  mov r2, #-3
becomes
  mvn r2, #2

rdar://10349224

llvm-svn: 143235

2 files changed, 29 insertions, 1 deletions

diff --git a/llvm/lib/Target/ARM/ARMInstrThumb2.td b/llvm/lib/Target/ARM/ARMInstrThumb2.td
index 9a48b1860fd..d06510744a1 100644
--- a/llvm/lib/Target/ARM/ARMInstrThumb2.td
+++ b/llvm/lib/Target/ARM/ARMInstrThumb2.td
@@ -76,10 +76,16 @@ def t2_so_imm : Operand<i32>, ImmLeaf<i32, [{
 
 // t2_so_imm_not - Match an immediate that is a complement
 // of a t2_so_imm.
+// Note: this pattern doesn't require an encoder method and such, as it's
+// only used on aliases (Pat<> and InstAlias<>). The actual encoding
+// is handled by the destination instructions, which use t2_so_imm.
+def t2_so_imm_not_asmoperand : AsmOperandClass { let Name = "T2SOImmNot"; }
 def t2_so_imm_not : Operand<i32>,
                     PatLeaf<(imm), [{
   return ARM_AM::getT2SOImmVal(~((uint32_t)N->getZExtValue())) != -1;
-}], t2_so_imm_not_XFORM>;
+}], t2_so_imm_not_XFORM> {
+  let ParserMatchClass = t2_so_imm_not_asmoperand;
+}
 
 // t2_so_imm_neg - Match an immediate that is a negation of a t2_so_imm.
 def t2_so_imm_neg : Operand<i32>,
@@ -4066,3 +4072,9 @@ def : t2InstAlias<"sxtb16${p} $Rd, $Rm$rot",
                   (t2SXTB16 rGPR:$Rd, rGPR:$Rm, rot_imm:$rot, pred:$p)>;
 def : t2InstAlias<"sxth${p} $Rd, $Rm$rot",
                   (t2SXTH rGPR:$Rd, rGPR:$Rm, rot_imm:$rot, pred:$p)>;
+
+
+// "mov Rd, t2_so_imm_not" can be handled via "mvn" in assembly, just like
+// for isel.
+def : t2InstAlias<"mov${p} $Rd, $imm",
+                  (t2MVNi rGPR:$Rd, t2_so_imm_not:$imm, pred:$p, zero_reg)>;
diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index dbdce29e107..ad5f061eaba 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -665,6 +665,14 @@ public:
     int64_t Value = CE->getValue();
     return ARM_AM::getT2SOImmVal(Value) != -1;
   }
+  bool isT2SOImmNot() const {
+    if (Kind != k_Immediate)
+      return false;
+    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
+    if (!CE) return false;
+    int64_t Value = CE->getValue();
+    return ARM_AM::getT2SOImmVal(~Value) != -1;
+  }
   bool isSetEndImm() const {
     if (Kind != k_Immediate)
       return false;
@@ -1241,6 +1249,14 @@ public:
     addExpr(Inst, getImm());
   }
 
+  void addT2SOImmNotOperands(MCInst &Inst, unsigned N) const {
+    assert(N == 1 && "Invalid number of operands!");
+    // The operand is actually a t2_so_imm, but we have its bitwise
+    // negation in the assembly source, so twiddle it here.
+    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
+    Inst.addOperand(MCOperand::CreateImm(~CE->getValue()));
+  }
+
   void addSetEndImmOperands(MCInst &Inst, unsigned N) const {
     assert(N == 1 && "Invalid number of operands!");
     addExpr(Inst, getImm());