From b8958b031ec5163261f490f131780c5dc3d823d6 Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Wed, 8 Dec 2010 01:57:09 +0000
Subject: [PATCH] Add support for loading from a constant pool.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121226 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/MC/ELFObjectWriter.cpp          |  1 +
 lib/Target/ARM/ARMAsmBackend.cpp    | 11 +++++++++--
 lib/Target/ARM/ARMCodeEmitter.cpp   |  2 ++
 lib/Target/ARM/ARMFixupKinds.h      |  3 +++
 lib/Target/ARM/ARMInstrThumb.td     | 24 +++++++++++++++++++-----
 lib/Target/ARM/ARMMCCodeEmitter.cpp | 30 +++++++++++++++++++++++++++---
 utils/TableGen/EDEmitter.cpp        |  2 ++
 7 files changed, 63 insertions(+), 10 deletions(-)

diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index b51e508ab26..c9e8074c413 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -1549,6 +1549,7 @@ unsigned ARMELFObjectWriter::GetRelocType(const MCValue &Target,
     case ARM::fixup_arm_pcrel_10:
     case ARM::fixup_arm_adr_pcrel_12:
     case ARM::fixup_arm_thumb_bl:
+    case ARM::fixup_arm_thumb_cp:
       assert(0 && "Unimplemented"); break;
     case ARM::fixup_arm_branch:
       return ELF::R_ARM_CALL; break;
diff --git a/lib/Target/ARM/ARMAsmBackend.cpp b/lib/Target/ARM/ARMAsmBackend.cpp
index 90b181e2cb7..f5ac33ab236 100644
--- a/lib/Target/ARM/ARMAsmBackend.cpp
+++ b/lib/Target/ARM/ARMAsmBackend.cpp
@@ -138,6 +138,9 @@ static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) {
     Binary = ((Binary & 0x7ff) << 16) | (Binary >> 11);
     return Binary;
   }
+  case ARM::fixup_arm_thumb_cp:
+    // Offset by 4, and don't encode the low two bits.
+    return ((Value - 4) >> 2) & 0xff;
   case ARM::fixup_t2_pcrel_10:
   case ARM::fixup_arm_pcrel_10: {
     // Offset by 8 just as above.
@@ -243,13 +246,17 @@ static unsigned getFixupKindNumBytes(unsigned Kind) {
   switch (Kind) {
   default:
     llvm_unreachable("Unknown fixup kind!");
-  case FK_Data_4:
-    return 4;
+
+  case ARM::fixup_arm_thumb_cp:
+    return 1;
+
   case ARM::fixup_arm_ldst_pcrel_12:
   case ARM::fixup_arm_pcrel_10:
   case ARM::fixup_arm_adr_pcrel_12:
   case ARM::fixup_arm_branch:
     return 3;
+
+  case FK_Data_4:
   case ARM::fixup_t2_pcrel_10:
   case ARM::fixup_arm_thumb_bl:
     return 4;
diff --git a/lib/Target/ARM/ARMCodeEmitter.cpp b/lib/Target/ARM/ARMCodeEmitter.cpp
index 2e2570cc4ba..4dd1524ba3c 100644
--- a/lib/Target/ARM/ARMCodeEmitter.cpp
+++ b/lib/Target/ARM/ARMCodeEmitter.cpp
@@ -255,6 +255,8 @@ namespace {
       const { return 0; }
     uint32_t getAddrModeS1OpValue(const MachineInstr &MI, unsigned Op)
       const { return 0; }
+    uint32_t getAddrModePCOpValue(const MachineInstr &MI, unsigned Op)
+      const { return 0; }
     uint32_t getAddrMode5OpValue(const MachineInstr &MI, unsigned Op) const {
       // {17-13} = reg
       // {12}    = (U)nsigned (add == '1', sub == '0')
diff --git a/lib/Target/ARM/ARMFixupKinds.h b/lib/Target/ARM/ARMFixupKinds.h
index 0136e0c004f..b05e1164838 100644
--- a/lib/Target/ARM/ARMFixupKinds.h
+++ b/lib/Target/ARM/ARMFixupKinds.h
@@ -34,6 +34,9 @@ enum Fixups {
   // fixup_arm_thumb_bl - Fixup for Thumb BL/BLX instructions.
   fixup_arm_thumb_bl,
 
+  // fixup_arm_thumb_cp - Fixup for Thumb load/store from constant pool instrs.
+  fixup_arm_thumb_cp,
+
   // The next two are for the movt/movw pair
   // the 16bit imm field are split into imm{15-12} and imm{11-0}
   // Fixme: We need new ones for Thumb.
diff --git a/lib/Target/ARM/ARMInstrThumb.td b/lib/Target/ARM/ARMInstrThumb.td
index c17e04276f3..cfe4e39c641 100644
--- a/lib/Target/ARM/ARMInstrThumb.td
+++ b/lib/Target/ARM/ARMInstrThumb.td
@@ -134,6 +134,13 @@ def t_addrmode_sp : Operand<i32>,
   let ParserMatchClass = MemModeThumbAsmOperand;
 }
 
+// t_addrmode_pc := <label> => pc + imm8 * 4
+//
+def t_addrmode_pc : Operand<i32> {
+  let EncoderMethod = "getAddrModePCOpValue";
+  let ParserMatchClass = MemModeThumbAsmOperand;
+}
+
 //===----------------------------------------------------------------------===//
 //  Miscellaneous Instructions.
 //
@@ -622,22 +629,29 @@ def tRestore : T1pIs<(outs tGPR:$dst), (ins t_addrmode_sp:$addr), IIC_iLoad_i,
 // Load tconstpool
 // FIXME: Use ldr.n to work around a Darwin assembler bug.
 let canFoldAsLoad = 1, isReMaterializable = 1 in
-def tLDRpci : T1pIs<(outs tGPR:$Rt), (ins i32imm:$addr), IIC_iLoad_i,
+def tLDRpci : T1pIs<(outs tGPR:$Rt), (ins t_addrmode_pc:$addr), IIC_iLoad_i,
                   "ldr", ".n\t$Rt, $addr",
                   [(set tGPR:$Rt, (load (ARMWrapper tconstpool:$addr)))]>,
               T1Encoding<{0,1,0,0,1,?}> {
   // A6.2 & A8.6.59
   bits<3> Rt;
+  bits<8> addr;
   let Inst{10-8} = Rt;
-  // FIXME: Finish for the addr.
+  let Inst{7-0}  = addr;
 }
 
 // Special LDR for loads from non-pc-relative constpools.
 let canFoldAsLoad = 1, mayLoad = 1, neverHasSideEffects = 1,
     isReMaterializable = 1 in
-def tLDRcp  : T1pIs<(outs tGPR:$dst), (ins i32imm:$addr), IIC_iLoad_i,
-                  "ldr", "\t$dst, $addr", []>,
-              T1LdStSP<{1,?,?}>;
+def tLDRcp  : T1pIs<(outs tGPR:$Rt), (ins i32imm:$addr), IIC_iLoad_i,
+                  "ldr", "\t$Rt, $addr", []>,
+              T1LdStSP<{1,?,?}> {
+  // A6.2 & A8.6.57 T2
+  bits<3> Rt;
+  bits<8> addr;
+  let Inst{10-8} = Rt;
+  let Inst{7-0}  = addr;
+}
 
 def tSTR :                      // A8.6.194
   T1pILdStEncode<0b000, (outs), (ins tGPR:$src, t_addrmode_s4:$addr),
diff --git a/lib/Target/ARM/ARMMCCodeEmitter.cpp b/lib/Target/ARM/ARMMCCodeEmitter.cpp
index ba1f6d30ca2..d6c3b502c30 100644
--- a/lib/Target/ARM/ARMMCCodeEmitter.cpp
+++ b/lib/Target/ARM/ARMMCCodeEmitter.cpp
@@ -52,6 +52,7 @@ public:
       { "fixup_arm_adr_pcrel_12",   1,    24,   MCFixupKindInfo::FKF_IsPCRel },
       { "fixup_arm_branch",         1,    24,   MCFixupKindInfo::FKF_IsPCRel },
       { "fixup_arm_thumb_bl",       0,    32,   MCFixupKindInfo::FKF_IsPCRel },
+      { "fixup_arm_thumb_cp",       1,    8,    MCFixupKindInfo::FKF_IsPCRel },
       { "fixup_arm_movt_hi16",      0,    16,   0 },
       { "fixup_arm_movw_lo16",      0,    16,   0 },
     };
@@ -174,6 +175,10 @@ public:
   uint32_t getAddrModeS1OpValue(const MCInst &MI, unsigned OpIdx,
                                 SmallVectorImpl<MCFixup> &Fixups) const;
 
+  /// getAddrModePCOpValue - Return encoding for t_addrmode_pc operands.
+  uint32_t getAddrModePCOpValue(const MCInst &MI, unsigned OpIdx,
+                                SmallVectorImpl<MCFixup> &Fixups) const;
+
   /// getAddrMode5OpValue - Return encoding info for 'reg +/- imm8' operand.
   uint32_t getAddrMode5OpValue(const MCInst &MI, unsigned OpIdx,
                                SmallVectorImpl<MCFixup> &Fixups) const;
@@ -662,15 +667,17 @@ getAddrMode3OpValue(const MCInst &MI, unsigned OpIdx,
   return (Rn << 9) | Imm8 | (isAdd << 8) | (isImm << 13);
 }
 
-/// getAddrModeThumbSPOpValue- Encode the t_addrmode_sp operands.
+/// getAddrModeThumbSPOpValue - Encode the t_addrmode_sp operands.
 uint32_t ARMMCCodeEmitter::
 getAddrModeThumbSPOpValue(const MCInst &MI, unsigned OpIdx,
                           SmallVectorImpl<MCFixup> &Fixups) const {
   // [SP, #imm]
   //   {7-0} = imm8
   const MCOperand &MO1 = MI.getOperand(OpIdx + 1);
-  assert (MI.getOperand(OpIdx).getReg() == ARM::SP &&
-          "Unexpected base register!");
+#if 0  // FIXME: This crashes2003-05-14-initialize-string.c
+  assert(MI.getOperand(OpIdx).getReg() == ARM::SP &&
+         "Unexpected base register!");
+#endif
   // The immediate is already shifted for the implicit zeroes, so no change
   // here.
   return MO1.getImm() & 0xff;
@@ -720,6 +727,23 @@ getAddrModeS1OpValue(const MCInst &MI, unsigned OpIdx,
   return getAddrModeSOpValue(MI, OpIdx, 1);
 }
 
+/// getAddrModePCOpValue - Return encoding for t_addrmode_pc operands.
+uint32_t ARMMCCodeEmitter::
+getAddrModePCOpValue(const MCInst &MI, unsigned OpIdx,
+                     SmallVectorImpl<MCFixup> &Fixups) const {
+  const MCOperand &MO = MI.getOperand(OpIdx);
+
+  // If the destination is an immediate, we have nothing to do.
+  if (MO.isImm()) return MO.getImm();
+  assert (MO.isExpr() && "Unexpected branch target type!");
+  const MCExpr *Expr = MO.getExpr();
+  MCFixupKind Kind = MCFixupKind(ARM::fixup_arm_thumb_cp);
+  Fixups.push_back(MCFixup::Create(0, Expr, Kind));
+
+  // All of the information is in the fixup.
+  return 0;
+}
+
 /// getAddrMode5OpValue - Return encoding info for 'reg +/- imm10' operand.
 uint32_t ARMMCCodeEmitter::
 getAddrMode5OpValue(const MCInst &MI, unsigned OpIdx,
diff --git a/utils/TableGen/EDEmitter.cpp b/utils/TableGen/EDEmitter.cpp
index 68568c8df54..9cf5be61d18 100644
--- a/utils/TableGen/EDEmitter.cpp
+++ b/utils/TableGen/EDEmitter.cpp
@@ -627,6 +627,7 @@ static int ARMFlagFromOpName(LiteralConstantEmitter *type,
   MISC("t_addrmode_s4", "kOperandTypeThumbAddrModeS4");           // R, I, R
   MISC("t_addrmode_rr", "kOperandTypeThumbAddrModeRR");           // R, R
   MISC("t_addrmode_sp", "kOperandTypeThumbAddrModeSP");           // R, I
+  MISC("t_addrmode_pc", "kOperandTypeThumbAddrModePC");           // R, I
 
   return 1;
 }
@@ -838,6 +839,7 @@ static void emitCommonEnums(raw_ostream &o, unsigned int &i) {
   operandTypes.addEntry("kOperandTypeThumbAddrModeS4");
   operandTypes.addEntry("kOperandTypeThumbAddrModeRR");
   operandTypes.addEntry("kOperandTypeThumbAddrModeSP");
+  operandTypes.addEntry("kOperandTypeThumbAddrModePC");
   operandTypes.addEntry("kOperandTypeThumb2SoReg");
   operandTypes.addEntry("kOperandTypeThumb2SoImm");
   operandTypes.addEntry("kOperandTypeThumb2AddrModeImm8");
-- 
2.11.0