Thumb2 alternate syntax for LDR(literal) and friends.

Explicit pc-relative syntax. For example, "ldrb r2, [pc, #-22]".

rdar://10250964

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148432 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 96 insertions, 0 deletions

diff --git a/lib/Target/ARM/ARMInstrThumb2.td b/lib/Target/ARM/ARMInstrThumb2.td
index da58146ec2..142ab222b8 100644
--- a/lib/Target/ARM/ARMInstrThumb2.td
+++ b/lib/Target/ARM/ARMInstrThumb2.td
@@ -136,6 +136,12 @@ def t2ldrlabel : Operand<i32> {
   let PrintMethod = "printT2LdrLabelOperand";
 }
 
+def t2ldr_pcrel_imm12_asmoperand : AsmOperandClass {let Name = "MemPCRelImm12";}
+def t2ldr_pcrel_imm12 : Operand<i32> {
+  let ParserMatchClass = t2ldr_pcrel_imm12_asmoperand;
+  // used for assembler pseudo instruction and maps to t2ldrlabel, so
+  // doesn't need encoder or print methods of its own.
+}
 
 // ADR instruction labels.
 def t2adrlabel : Operand<i32> {
@@ -4151,3 +4157,26 @@ def t2MOVSsr: t2AsmPseudo<"movs${p} $Rd, $shift",
 // ADR w/o the .w suffix
 def : t2InstAlias<"adr${p} $Rd, $addr",
                   (t2ADR rGPR:$Rd, t2adrlabel:$addr, pred:$p)>;
+
+// LDR(literal) w/ alternate [pc, #imm] syntax.
+def t2LDRpcrel   : t2AsmPseudo<"ldr${p} $Rt, $addr",
+                         (ins GPRnopc:$Rt, t2ldr_pcrel_imm12:$addr, pred:$p)>;
+def t2LDRBpcrel  : t2AsmPseudo<"ldrb${p} $Rt, $addr",
+                         (ins GPRnopc:$Rt, t2ldr_pcrel_imm12:$addr, pred:$p)>;
+def t2LDRHpcrel  : t2AsmPseudo<"ldrh${p} $Rt, $addr",
+                         (ins GPRnopc:$Rt, t2ldr_pcrel_imm12:$addr, pred:$p)>;
+def t2LDRSBpcrel  : t2AsmPseudo<"ldrsb${p} $Rt, $addr",
+                         (ins GPRnopc:$Rt, t2ldr_pcrel_imm12:$addr, pred:$p)>;
+def t2LDRSHpcrel  : t2AsmPseudo<"ldrsh${p} $Rt, $addr",
+                         (ins GPRnopc:$Rt, t2ldr_pcrel_imm12:$addr, pred:$p)>;
+    // Version w/ the .w suffix.
+def : t2InstAlias<"ldr${p}.w $Rt, $addr",
+                  (t2LDRpcrel GPRnopc:$Rt, t2ldr_pcrel_imm12:$addr, pred:$p)>;
+def : t2InstAlias<"ldrb${p}.w $Rt, $addr",
+                  (t2LDRBpcrel GPRnopc:$Rt, t2ldr_pcrel_imm12:$addr, pred:$p)>;
+def : t2InstAlias<"ldrh${p}.w $Rt, $addr",
+                  (t2LDRHpcrel GPRnopc:$Rt, t2ldr_pcrel_imm12:$addr, pred:$p)>;
+def : t2InstAlias<"ldrsb${p}.w $Rt, $addr",
+                  (t2LDRSBpcrel GPRnopc:$Rt, t2ldr_pcrel_imm12:$addr, pred:$p)>;
+def : t2InstAlias<"ldrsh${p}.w $Rt, $addr",
+                  (t2LDRSHpcrel GPRnopc:$Rt, t2ldr_pcrel_imm12:$addr, pred:$p)>;
diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 021803de71..29a02f6959 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -838,6 +838,17 @@ public:
     return Memory.OffsetRegNum == 0 && Memory.OffsetImm == 0 &&
      (alignOK || Memory.Alignment == 0);
   }
+  bool isMemPCRelImm12() const {
+    if (!isMemory() || Memory.OffsetRegNum != 0 || Memory.Alignment != 0)
+      return false;
+    // Base register must be PC.
+    if (Memory.BaseRegNum != ARM::PC)
+      return false;
+    // Immediate offset in range [-4095, 4095].
+    if (!Memory.OffsetImm) return true;
+    int64_t Val = Memory.OffsetImm->getValue();
+    return (Val > -4096 && Val < 4096) || (Val == INT32_MIN);
+  }
   bool isAlignedMemory() const {
     return isMemNoOffset(true);
   }
@@ -999,6 +1010,8 @@ public:
   bool isMemImm8Offset() const {
     if (!isMemory() || Memory.OffsetRegNum != 0 || Memory.Alignment != 0)
       return false;
+    // Base reg of PC isn't allowed for these encodings.
+    if (Memory.BaseRegNum == ARM::PC) return false;
     // Immediate offset in range [-255, 255].
     if (!Memory.OffsetImm) return true;
     int64_t Val = Memory.OffsetImm->getValue();
@@ -1015,6 +1028,8 @@ public:
   bool isMemNegImm8Offset() const {
     if (!isMemory() || Memory.OffsetRegNum != 0 || Memory.Alignment != 0)
       return false;
+    // Base reg of PC isn't allowed for these encodings.
+    if (Memory.BaseRegNum == ARM::PC) return false;
     // Immediate offset in range [-255, -1].
     if (!Memory.OffsetImm) return false;
     int64_t Val = Memory.OffsetImm->getValue();
@@ -1482,6 +1497,14 @@ public:
     Inst.addOperand(MCOperand::CreateReg(Memory.BaseRegNum));
   }
 
+  void addMemPCRelImm12Operands(MCInst &Inst, unsigned N) const {
+    assert(N == 1 && "Invalid number of operands!");
+    int32_t Imm = Memory.OffsetImm->getValue();
+    // FIXME: Handle #-0
+    if (Imm == INT32_MIN) Imm = 0;
+    Inst.addOperand(MCOperand::CreateImm(Imm));
+  }
+
   void addAlignedMemoryOperands(MCInst &Inst, unsigned N) const {
     assert(N == 2 && "Invalid number of operands!");
     Inst.addOperand(MCOperand::CreateReg(Memory.BaseRegNum));
@@ -5389,6 +5412,22 @@ bool ARMAsmParser::
 processInstruction(MCInst &Inst,
                    const SmallVectorImpl<MCParsedAsmOperand*> &Operands) {
   switch (Inst.getOpcode()) {
+  // Aliases for alternate PC+imm syntax of LDR instructions.
+  case ARM::t2LDRpcrel:
+    Inst.setOpcode(ARM::t2LDRpci);
+    return true;
+  case ARM::t2LDRBpcrel:
+    Inst.setOpcode(ARM::t2LDRBpci);
+    return true;
+  case ARM::t2LDRHpcrel:
+    Inst.setOpcode(ARM::t2LDRHpci);
+    return true;
+  case ARM::t2LDRSBpcrel:
+    Inst.setOpcode(ARM::t2LDRSBpci);
+    return true;
+  case ARM::t2LDRSHpcrel:
+    Inst.setOpcode(ARM::t2LDRSHpci);
+    return true;
   // Handle NEON VST complex aliases.
   case ARM::VST1LNdWB_register_Asm_8: case ARM::VST1LNdWB_register_Asm_P8:
   case ARM::VST1LNdWB_register_Asm_I8: case ARM::VST1LNdWB_register_Asm_S8:
diff --git a/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp b/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
index 1bfefa7c0e..768eaea189 100644
--- a/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
+++ b/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
@@ -723,6 +723,7 @@ getAddrModeImm12OpValue(const MCInst &MI, unsigned OpIdx,
     } else {
       Reg = ARM::PC;
       int32_t Offset = MO.getImm();
+      // FIXME: Handle #-0.
       if (Offset < 0) {
         Offset *= -1;
         isAdd = false;
diff --git a/test/MC/ARM/basic-thumb2-instructions.s b/test/MC/ARM/basic-thumb2-instructions.s
index 9daeb9d2c4..78311af9b6 100644
--- a/test/MC/ARM/basic-thumb2-instructions.s
+++ b/test/MC/ARM/basic-thumb2-instructions.s
@@ -3323,3 +3323,30 @@ _func:
 @ CHECK: wfelt                          @ encoding: [0x20,0xbf]
 @ CHECK: wfige                          @ encoding: [0x30,0xbf]
 @ CHECK: yieldlt                        @ encoding: [0x10,0xbf]
+
+
+@------------------------------------------------------------------------------
+@ Alternate syntax for LDR*(literal) encodings
+@------------------------------------------------------------------------------
+        ldr r11, [pc, #-22]
+        ldrb r11, [pc, #-22]
+        ldrh r11, [pc, #-22]
+        ldrsb r11, [pc, #-22]
+        ldrsh r11, [pc, #-22]
+
+        ldr.w r11, [pc, #-22]
+        ldrb.w r11, [pc, #-22]
+        ldrh.w r11, [pc, #-22]
+        ldrsb.w r11, [pc, #-22]
+        ldrsh.w r11, [pc, #-22]
+
+@ CHECK: ldr.w	r11, [pc, #-22]         @ encoding: [0x5f,0xf8,0x16,0xb0]
+@ CHECK: ldrb.w	r11, [pc, #-22]         @ encoding: [0x1f,0xf8,0x16,0xb0]
+@ CHECK: ldrh.w	r11, [pc, #-22]         @ encoding: [0x3f,0xf8,0x16,0xb0]
+@ CHECK: ldrsb.w r11, [pc, #-22]        @ encoding: [0x1f,0xf9,0x16,0xb0]
+@ CHECK: ldrsh.w r11, [pc, #-22]        @ encoding: [0x3f,0xf9,0x16,0xb0]
+@ CHECK: ldr.w	r11, [pc, #-22]         @ encoding: [0x5f,0xf8,0x16,0xb0]
+@ CHECK: ldrb.w	r11, [pc, #-22]         @ encoding: [0x1f,0xf8,0x16,0xb0]
+@ CHECK: ldrh.w	r11, [pc, #-22]         @ encoding: [0x3f,0xf8,0x16,0xb0]
+@ CHECK: ldrsb.w r11, [pc, #-22]        @ encoding: [0x1f,0xf9,0x16,0xb0]
+@ CHECK: ldrsh.w r11, [pc, #-22]        @ encoding: [0x3f,0xf9,0x16,0xb0]