MC: support different sized constants in constant pools

    
On AArch64 the pseudo instruction ldr <reg>, =... supports both
32-bit and 64-bit constants. Add support for 64 bit constants for
the pools to support the pseudo instruction fully.

Changes the AArch64 ldr-pseudo tests to use 32-bit registers and
adds tests with 64-bit registers.

Patch by Janne Grunau!

Differential Revision: http://reviews.llvm.org/D4279

llvm-svn: 213387

llvm/include/llvm/MC/ConstantPools.h

@@ -22,10 +22,17 @@ class MCExpr;
 class MCSection;
 class MCStreamer;
 class MCSymbol;
+
+struct ConstantPoolEntry {
+  MCSymbol *Label;
+  const MCExpr *Value;
+  unsigned Size;
+};
+
 // A class to keep track of assembler-generated constant pools that are use to
 // implement the ldr-pseudo.
 class ConstantPool {
-  typedef SmallVector<std::pair<MCSymbol *, const MCExpr *>, 4> EntryVecTy;
+  typedef SmallVector<ConstantPoolEntry, 4> EntryVecTy;
   EntryVecTy Entries;
 
 public:
@@ -34,9 +41,11 @@ class ConstantPool {
 
   // Add a new entry to the constant pool in the next slot.
   // \param Value is the new entry to put in the constant pool.
+  // \param Size is the size in bytes of the entry
   //
   // \returns a MCExpr that references the newly inserted value
-  const MCExpr *addEntry(const MCExpr *Value, MCContext &Context);
+  const MCExpr *addEntry(const MCExpr *Value, MCContext &Context,
+                         unsigned Size);
 
   // Emit the contents of the constant pool using the provided streamer.
   void emitEntries(MCStreamer &Streamer);
@@ -69,7 +78,8 @@ class AssemblerConstantPools {
 
   void emitAll(MCStreamer &Streamer);
   void emitForCurrentSection(MCStreamer &Streamer);
-  const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr);
+  const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr,
+                         unsigned Size);
 
 private:
   ConstantPool *getConstantPool(const MCSection *Section);

llvm/include/llvm/MC/MCStreamer.h

@@ -97,7 +97,7 @@ class AArch64TargetStreamer : public MCTargetStreamer {
   /// Callback used to implement the ldr= pseudo.
   /// Add a new entry to the constant pool for the current section and return an
   /// MCExpr that can be used to refer to the constant pool location.
-  const MCExpr *addConstantPoolEntry(const MCExpr *);
+  const MCExpr *addConstantPoolEntry(const MCExpr *, unsigned Size);
 
   /// Callback used to implemnt the .ltorg directive.
   /// Emit contents of constant pool for the current section.

llvm/lib/MC/ConstantPools.cpp

@@ -24,21 +24,22 @@ using namespace llvm;
 void ConstantPool::emitEntries(MCStreamer &Streamer) {
   if (Entries.empty())
     return;
-  Streamer.EmitCodeAlignment(4); // align to 4-byte address
   Streamer.EmitDataRegion(MCDR_DataRegion);
   for (EntryVecTy::const_iterator I = Entries.begin(), E = Entries.end();
        I != E; ++I) {
-    Streamer.EmitLabel(I->first);
-    Streamer.EmitValue(I->second, 4);
+    Streamer.EmitCodeAlignment(I->Size); // align naturally
+    Streamer.EmitLabel(I->Label);
+    Streamer.EmitValue(I->Value, I->Size);
   }
   Streamer.EmitDataRegion(MCDR_DataRegionEnd);
   Entries.clear();
 }
 
-const MCExpr *ConstantPool::addEntry(const MCExpr *Value, MCContext &Context) {
+const MCExpr *ConstantPool::addEntry(const MCExpr *Value, MCContext &Context,
+                                     unsigned Size) {
   MCSymbol *CPEntryLabel = Context.CreateTempSymbol();
 
-  Entries.push_back(std::make_pair(CPEntryLabel, Value));
+  Entries.push_back( { CPEntryLabel, Value, Size } );
   return MCSymbolRefExpr::Create(CPEntryLabel, Context);
 }
 
@@ -89,7 +90,9 @@ void AssemblerConstantPools::emitForCurrentSection(MCStreamer &Streamer) {
 }
 
 const MCExpr *AssemblerConstantPools::addEntry(MCStreamer &Streamer,
-                                               const MCExpr *Expr) {
+                                               const MCExpr *Expr,
+                                               unsigned Size) {
   const MCSection *Section = Streamer.getCurrentSection().first;
-  return getOrCreateConstantPool(Section).addEntry(Expr, Streamer.getContext());
+  return getOrCreateConstantPool(Section).addEntry(Expr, Streamer.getContext(),
+                                                   Size);
 }

llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

@@ -25,6 +25,7 @@
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/ADT/APInt.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/STLExtras.h"
@@ -3067,13 +3068,18 @@ bool AArch64AsmParser::parseOperand(OperandVector &Operands, bool isCondCode,
     if (getParser().parseExpression(SubExprVal))
       return true;
 
+    if (Operands.size() < 2 ||
+        !static_cast<AArch64Operand &>(*Operands[1]).isReg())
+      return true;
+
+    bool IsXReg =
+        AArch64MCRegisterClasses[AArch64::GPR64allRegClassID].contains(
+            Operands[1]->getReg());
+
     MCContext& Ctx = getContext();
     E = SMLoc::getFromPointer(Loc.getPointer() - 1);
     // If the op is an imm and can be fit into a mov, then replace ldr with mov.
-    if (isa<MCConstantExpr>(SubExprVal) && Operands.size() >= 2 &&
-        static_cast<AArch64Operand &>(*Operands[1]).isReg()) {
-      bool IsXReg =  AArch64MCRegisterClasses[AArch64::GPR64allRegClassID].contains(
-            Operands[1]->getReg());
+    if (isa<MCConstantExpr>(SubExprVal)) {
       uint64_t Imm = (cast<MCConstantExpr>(SubExprVal))->getValue();
       uint32_t ShiftAmt = 0, MaxShiftAmt = IsXReg ? 48 : 16;
       while(Imm > 0xFFFF && countTrailingZeros(Imm) >= 16) {
@@ -3089,9 +3095,14 @@ bool AArch64AsmParser::parseOperand(OperandVector &Operands, bool isCondCode,
                      ShiftAmt, true, S, E, Ctx));
         return false;
       }
+      APInt Simm = APInt(64, Imm << ShiftAmt);
+      // check if the immediate is an unsigned or signed 32-bit int for W regs
+      if (!IsXReg && !(Simm.isIntN(32) || Simm.isSignedIntN(32)))
+        return Error(Loc, "Immediate too large for register");
     }
     // If it is a label or an imm that cannot fit in a movz, put it into CP.
-    const MCExpr *CPLoc = getTargetStreamer().addConstantPoolEntry(SubExprVal);
+    const MCExpr *CPLoc =
+        getTargetStreamer().addConstantPoolEntry(SubExprVal, IsXReg ? 8 : 4);
     Operands.push_back(AArch64Operand::CreateImm(CPLoc, S, E, Ctx));
     return false;
   }

llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.cpp

@@ -28,8 +28,9 @@ AArch64TargetStreamer::~AArch64TargetStreamer() {}
 
 // The constant pool handling is shared by all AArch64TargetStreamer
 // implementations.
-const MCExpr *AArch64TargetStreamer::addConstantPoolEntry(const MCExpr *Expr) {
-  return ConstantPools->addEntry(Streamer, Expr);
+const MCExpr *AArch64TargetStreamer::addConstantPoolEntry(const MCExpr *Expr,
+                                                          unsigned Size) {
+  return ConstantPools->addEntry(Streamer, Expr, Size);
 }
 
 void AArch64TargetStreamer::emitCurrentConstantPool() {

llvm/lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp

@@ -28,7 +28,7 @@ ARMTargetStreamer::~ARMTargetStreamer() {}
 // The constant pool handling is shared by all ARMTargetStreamer
 // implementations.
 const MCExpr *ARMTargetStreamer::addConstantPoolEntry(const MCExpr *Expr) {
-  return ConstantPools->addEntry(Streamer, Expr);
+  return ConstantPools->addEntry(Streamer, Expr, 4);
 }
 
 void ARMTargetStreamer::emitCurrentConstantPool() {

llvm/test/MC/AArch64/ldr-pseudo-diagnostics.s

@@ -0,0 +1,14 @@
+//RUN: not llvm-mc -triple=aarch64-linux-gnu - < %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
+
+// simple test
+.section a, "ax", @progbits
+f1:
+  ldr w0, =0x100000001
+// CHECK-ERROR: error: Immediate too large for register
+// CHECK-ERROR:   ldr w0, =0x100000001
+// CHECK-ERROR:           ^
+f2:
+  ldr w0, =-0x80000001
+// CHECK-ERROR: error: Immediate too large for register
+// CHECK-ERROR:  ldr w0, =-0x80000001
+// CHECK-ERROR:          ^