[AArch64] Implement pseudo LDR <reg>, =<literal/label>

[weimingz]

Summary

See bugzilla: http://llvm.org/bugs/show_bug.cgi?id=20056

[dpeixott]

Overall this looks good to me, but I think we should split this into two commits: 1 factoring commit that moves the constant pools to a place that can be accessed by both AArch64 and ARM backends, and a second commit to implement the ldr= psuedo for AArch64.

test/MC/AArch64/ldr-pseudo.s

1 ↗

(On Diff #10456)

Either add the corresponding test for darwin, or delete this comment. I'm not sure if it is applicable for aarch64, or if the syntax is now unified between linux and darwin.

[dpeixott]

Adding llvm-commits to CC.

[weimingz]

This is the refactoring part.

[dpeixott]

LGTM with a suitable commit message explaining why we want to split out the implementation.

[weimingz]

In D4163#9, @dpeixott wrote:

LGTM with a suitable commit message explaining why we want to split out the implementation.

Thanks for reviewing, David. I committed the refactoring part as r211198.

[weimingz]

This is the second part (for aarch64).

[dpeixott]

Minor cleanup, otherwise LGTM.

As a suggestion for the future I think it would be better to start a new differential revision for each patch. Also, if you add "Differential Revison: <url>" to the commit message it will close it automatically on commit.

lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

3031 ↗

(On Diff #10583)

use cast<> instead of dyn_cast<> when not checking the return value for null.

[dpeixott]

LGTM.

[weimingz]

Closed by commit rL211533 (authored by @weimingz).

include/llvm/MC/ConstantPools.h

+//===- ConstantPool.h - Keep track of assembler-generated  ------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the ConstantPool and AssemblerConstantPools classes.
+//
+//===----------------------------------------------------------------------===//
+
+
+#ifndef LLVM_MC_CONSTANTPOOL_H
+#define LLVM_MC_CONSTANTPOOL_H
+
+#include "llvm/ADT/SmallVector.h"
+namespace llvm {
+class MCContext;
+class MCExpr;
+class MCSection;
+class MCStreamer;
+class MCSymbol;
+// 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;
+  EntryVecTy Entries;
+
+public:
+  // Initialize a new empty constant pool
+  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.
+  //
+  // \returns a MCExpr that references the newly inserted value
+  const MCExpr *addEntry(const MCExpr *Value, MCContext &Context);
+
+  // Emit the contents of the constant pool using the provided streamer.
+  void emitEntries(MCStreamer &Streamer);
+
+  // Return true if the constant pool is empty
+  bool empty();
+};
+
+class AssemblerConstantPools {
+  // Map type used to keep track of per-Section constant pools used by the
+  // ldr-pseudo opcode. The map associates a section to its constant pool. The
+  // constant pool is a vector of (label, value) pairs. When the ldr
+  // pseudo is parsed we insert a new (label, value) pair into the constant pool
+  // for the current section and add MCSymbolRefExpr to the new label as
+  // an opcode to the ldr. After we have parsed all the user input we
+  // output the (label, value) pairs in each constant pool at the end of the
+  // section.
+  //
+  // We use the MapVector for the map type to ensure stable iteration of
+  // the sections at the end of the parse. We need to iterate over the
+  // sections in a stable order to ensure that we have print the
+  // constant pools in a deterministic order when printing an assembly
+  // file.
+  typedef MapVector<const MCSection *, ConstantPool> ConstantPoolMapTy;
+  ConstantPoolMapTy ConstantPools;
+
+public:
+  AssemblerConstantPools() {}
+  ~AssemblerConstantPools() {}
+
+  void emitAll(MCStreamer &Streamer);
+  void emitForCurrentSection(MCStreamer &Streamer);
+  const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr);
+
+private:
+  ConstantPool *getConstantPool(const MCSection *Section);
+  ConstantPool &getOrCreateConstantPool(const MCSection *Section);
+};
+} // end namespace llvm
+
+#endif

lib/MC/CMakeLists.txt

 add_llvm_library(LLVMMC
+  ConstantPools.cpp
   ELFObjectWriter.cpp
   MCAsmBackend.cpp
   MCAsmInfo.cpp

lib/MC/ConstantPools.cpp

+//===- ConstantPools.cpp - ConstantPool class --*- C++ -*---------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the ConstantPool and  AssemblerConstantPools classes.
+//
+//===----------------------------------------------------------------------===//
+#include "llvm/ADT/MapVector.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/MC/ConstantPools.h"
+
+using namespace llvm;
+//
+// ConstantPool implementation
+//
+// Emit the contents of the constant pool using the provided streamer.
+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.EmitDataRegion(MCDR_DataRegionEnd);
+  Entries.clear();
+}
+
+const MCExpr *ConstantPool::addEntry(const MCExpr *Value, MCContext &Context) {
+  MCSymbol *CPEntryLabel = Context.CreateTempSymbol();
+
+  Entries.push_back(std::make_pair(CPEntryLabel, Value));
+  return MCSymbolRefExpr::Create(CPEntryLabel, Context);
+}
+
+bool ConstantPool::empty() { return Entries.empty(); }
+
+//
+// AssemblerConstantPools implementation
+//
+ConstantPool *
+AssemblerConstantPools::getConstantPool(const MCSection *Section) {
+  ConstantPoolMapTy::iterator CP = ConstantPools.find(Section);
+  if (CP == ConstantPools.end())
+    return nullptr;
+
+  return &CP->second;
+}
+
+ConstantPool &
+AssemblerConstantPools::getOrCreateConstantPool(const MCSection *Section) {
+  return ConstantPools[Section];
+}
+
+static void emitConstantPool(MCStreamer &Streamer, const MCSection *Section,
+                             ConstantPool &CP) {
+  if (!CP.empty()) {
+    Streamer.SwitchSection(Section);
+    CP.emitEntries(Streamer);
+  }
+}
+
+void AssemblerConstantPools::emitAll(MCStreamer &Streamer) {
+  // Dump contents of assembler constant pools.
+  for (ConstantPoolMapTy::iterator CPI = ConstantPools.begin(),
+                                   CPE = ConstantPools.end();
+       CPI != CPE; ++CPI) {
+    const MCSection *Section = CPI->first;
+    ConstantPool &CP = CPI->second;
+
+    emitConstantPool(Streamer, Section, CP);
+  }
+}
+
+void AssemblerConstantPools::emitForCurrentSection(MCStreamer &Streamer) {
+  const MCSection *Section = Streamer.getCurrentSection().first;
+  if (ConstantPool *CP = getConstantPool(Section)) {
+    emitConstantPool(Streamer, Section, *CP);
+  }
+}
+
+const MCExpr *AssemblerConstantPools::addEntry(MCStreamer &Streamer,
+                                               const MCExpr *Expr) {
+  const MCSection *Section = Streamer.getCurrentSection().first;
+  return getOrCreateConstantPool(Section).addEntry(Expr, Streamer.getContext());
+}

lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp

 //
 //===----------------------------------------------------------------------===//
 #include "llvm/ADT/MapVector.h"
+#include "llvm/MC/ConstantPools.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCStreamer.h"
 
 using namespace llvm;
-
-namespace {
-// 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;
-  EntryVecTy Entries;
-
-public:
-  // Initialize a new empty constant pool
-  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.
-  //
-  // \returns a MCExpr that references the newly inserted value
-  const MCExpr *addEntry(const MCExpr *Value, MCContext &Context);
-
-  // Emit the contents of the constant pool using the provided streamer.
-  void emitEntries(MCStreamer &Streamer);
-
-  // Return true if the constant pool is empty
-  bool empty();
-};
-}
-
-namespace llvm {
-class AssemblerConstantPools {
-  // Map type used to keep track of per-Section constant pools used by the
-  // ldr-pseudo opcode. The map associates a section to its constant pool. The
-  // constant pool is a vector of (label, value) pairs. When the ldr
-  // pseudo is parsed we insert a new (label, value) pair into the constant pool
-  // for the current section and add MCSymbolRefExpr to the new label as
-  // an opcode to the ldr. After we have parsed all the user input we
-  // output the (label, value) pairs in each constant pool at the end of the
-  // section.
-  //
-  // We use the MapVector for the map type to ensure stable iteration of
-  // the sections at the end of the parse. We need to iterate over the
-  // sections in a stable order to ensure that we have print the
-  // constant pools in a deterministic order when printing an assembly
-  // file.
-  typedef MapVector<const MCSection *, ConstantPool> ConstantPoolMapTy;
-  ConstantPoolMapTy ConstantPools;
-
-public:
-  AssemblerConstantPools() {}
-  ~AssemblerConstantPools() {}
-
-  void emitAll(MCStreamer &Streamer);
-  void emitForCurrentSection(MCStreamer &Streamer);
-  const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr);
-
-private:
-  ConstantPool *getConstantPool(const MCSection *Section);
-  ConstantPool &getOrCreateConstantPool(const MCSection *Section);
-};
-}
-
-//
-// ConstantPool implementation
-//
-// Emit the contents of the constant pool using the provided streamer.
-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.EmitDataRegion(MCDR_DataRegionEnd);
-  Entries.clear();
-}
-
-const MCExpr *ConstantPool::addEntry(const MCExpr *Value, MCContext &Context) {
-  MCSymbol *CPEntryLabel = Context.CreateTempSymbol();
-
-  Entries.push_back(std::make_pair(CPEntryLabel, Value));
-  return MCSymbolRefExpr::Create(CPEntryLabel, Context);
-}
-
-bool ConstantPool::empty() { return Entries.empty(); }
-
-//
-// AssemblerConstantPools implementation
-//
-ConstantPool *
-AssemblerConstantPools::getConstantPool(const MCSection *Section) {
-  ConstantPoolMapTy::iterator CP = ConstantPools.find(Section);
-  if (CP == ConstantPools.end())
-    return nullptr;
-
-  return &CP->second;
-}
-
-ConstantPool &
-AssemblerConstantPools::getOrCreateConstantPool(const MCSection *Section) {
-  return ConstantPools[Section];
-}
-
-static void emitConstantPool(MCStreamer &Streamer, const MCSection *Section,
-                             ConstantPool &CP) {
-  if (!CP.empty()) {
-    Streamer.SwitchSection(Section);
-    CP.emitEntries(Streamer);
-  }
-}
-
-void AssemblerConstantPools::emitAll(MCStreamer &Streamer) {
-  // Dump contents of assembler constant pools.
-  for (ConstantPoolMapTy::iterator CPI = ConstantPools.begin(),
-                                   CPE = ConstantPools.end();
-       CPI != CPE; ++CPI) {
-    const MCSection *Section = CPI->first;
-    ConstantPool &CP = CPI->second;
-
-    emitConstantPool(Streamer, Section, CP);
-  }
-}
-
-void AssemblerConstantPools::emitForCurrentSection(MCStreamer &Streamer) {
-  const MCSection *Section = Streamer.getCurrentSection().first;
-  if (ConstantPool *CP = getConstantPool(Section)) {
-    emitConstantPool(Streamer, Section, *CP);
-  }
-}
-
-const MCExpr *AssemblerConstantPools::addEntry(MCStreamer &Streamer,
-                                               const MCExpr *Expr) {
-  const MCSection *Section = Streamer.getCurrentSection().first;
-  return getOrCreateConstantPool(Section).addEntry(Expr, Streamer.getContext());
-}
-
 //
 // ARMTargetStreamer Implemenation
 //