[Sparc] Add support for 13-bit PIC

Summary: When compiling with -fpic, in contrast to -fPIC, use only the
immediate field to index into the GOT. This saves space if the GOT is
known to be small. The linker will warn if the GOT is too large for
this method.

Reviewers: jyknight, venkatra

Reviewed By: jyknight

Subscribers: brad, fedor.sergeev, jrtc27, llvm-commits

Differential Revision: https://reviews.llvm.org/D47136

llvm-svn: 334383

7 files changed, 49 insertions, 7 deletions

diff --git a/llvm/lib/Target/Sparc/AsmParser/SparcAsmParser.cpp b/llvm/lib/Target/Sparc/AsmParser/SparcAsmParser.cpp
index 35d92a96abe..c7a5a1e8e6e 100644
--- a/llvm/lib/Target/Sparc/AsmParser/SparcAsmParser.cpp
+++ b/llvm/lib/Target/Sparc/AsmParser/SparcAsmParser.cpp
@@ -885,9 +885,17 @@ SparcAsmParser::parseSparcAsmOperand(std::unique_ptr<SparcOperand> &Op,
 
       const MCExpr *Res = MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_None,
                                                   getContext());
-      if (isCall && getContext().getObjectFileInfo()->isPositionIndependent())
-        Res = SparcMCExpr::create(SparcMCExpr::VK_Sparc_WPLT30, Res,
-                                  getContext());
+      SparcMCExpr::VariantKind Kind = SparcMCExpr::VK_Sparc_13;
+
+      if (getContext().getObjectFileInfo()->isPositionIndependent()) {
+        if (isCall)
+          Kind = SparcMCExpr::VK_Sparc_WPLT30;
+        else
+          Kind = SparcMCExpr::VK_Sparc_GOT13;
+      }
+
+      Res = SparcMCExpr::create(Kind, Res, getContext());
+
       Op = SparcOperand::CreateImm(Res, S, E);
     }
     break;
diff --git a/llvm/lib/Target/Sparc/MCTargetDesc/SparcAsmBackend.cpp b/llvm/lib/Target/Sparc/MCTargetDesc/SparcAsmBackend.cpp
index 4b6c1de7d85..5f5e2ef7d45 100644
--- a/llvm/lib/Target/Sparc/MCTargetDesc/SparcAsmBackend.cpp
+++ b/llvm/lib/Target/Sparc/MCTargetDesc/SparcAsmBackend.cpp
@@ -54,6 +54,10 @@ static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) {
   case Sparc::fixup_sparc_hi22:
     return (Value >> 10) & 0x3fffff;
 
+  case Sparc::fixup_sparc_got13:
+  case Sparc::fixup_sparc_13:
+    return Value & 0x1fff;
+
   case Sparc::fixup_sparc_pc10:
   case Sparc::fixup_sparc_got10:
   case Sparc::fixup_sparc_tls_gd_lo10:
@@ -120,6 +124,7 @@ namespace {
         { "fixup_sparc_br19",      13,     19,  MCFixupKindInfo::FKF_IsPCRel },
         { "fixup_sparc_br16_2",    10,      2,  MCFixupKindInfo::FKF_IsPCRel },
         { "fixup_sparc_br16_14",   18,     14,  MCFixupKindInfo::FKF_IsPCRel },
+        { "fixup_sparc_13",        19,     13,  0 },
         { "fixup_sparc_hi22",      10,     22,  0 },
         { "fixup_sparc_lo10",      22,     10,  0 },
         { "fixup_sparc_h44",       10,     22,  0 },
@@ -131,6 +136,7 @@ namespace {
         { "fixup_sparc_pc10",      22,     10,  MCFixupKindInfo::FKF_IsPCRel },
         { "fixup_sparc_got22",     10,     22,  0 },
         { "fixup_sparc_got10",     22,     10,  0 },
+        { "fixup_sparc_got13",     19,     13,  0 },
         { "fixup_sparc_wplt30",     2,     30,  MCFixupKindInfo::FKF_IsPCRel },
         { "fixup_sparc_tls_gd_hi22",   10, 22,  0 },
         { "fixup_sparc_tls_gd_lo10",   22, 10,  0 },
@@ -159,6 +165,7 @@ namespace {
         { "fixup_sparc_br19",       0,     19,  MCFixupKindInfo::FKF_IsPCRel },
         { "fixup_sparc_br16_2",    20,      2,  MCFixupKindInfo::FKF_IsPCRel },
         { "fixup_sparc_br16_14",    0,     14,  MCFixupKindInfo::FKF_IsPCRel },
+        { "fixup_sparc_13",         0,     13,  0 },
         { "fixup_sparc_hi22",       0,     22,  0 },
         { "fixup_sparc_lo10",       0,     10,  0 },
         { "fixup_sparc_h44",        0,     22,  0 },
@@ -170,6 +177,7 @@ namespace {
         { "fixup_sparc_pc10",       0,     10,  MCFixupKindInfo::FKF_IsPCRel },
         { "fixup_sparc_got22",      0,     22,  0 },
         { "fixup_sparc_got10",      0,     10,  0 },
+        { "fixup_sparc_got13",      0,     13,  0 },
         { "fixup_sparc_wplt30",      0,     30,  MCFixupKindInfo::FKF_IsPCRel },
         { "fixup_sparc_tls_gd_hi22",    0, 22,  0 },
         { "fixup_sparc_tls_gd_lo10",    0, 10,  0 },
diff --git a/llvm/lib/Target/Sparc/MCTargetDesc/SparcELFObjectWriter.cpp b/llvm/lib/Target/Sparc/MCTargetDesc/SparcELFObjectWriter.cpp
index 173ef8674c1..5a730947796 100644
--- a/llvm/lib/Target/Sparc/MCTargetDesc/SparcELFObjectWriter.cpp
+++ b/llvm/lib/Target/Sparc/MCTargetDesc/SparcELFObjectWriter.cpp
@@ -79,6 +79,7 @@ unsigned SparcELFObjectWriter::getRelocType(MCContext &Ctx,
   case FK_Data_8:                return ((Fixup.getOffset() % 8)
                                          ? ELF::R_SPARC_UA64
                                          : ELF::R_SPARC_64);
+  case Sparc::fixup_sparc_13:    return ELF::R_SPARC_13;
   case Sparc::fixup_sparc_hi22:  return ELF::R_SPARC_HI22;
   case Sparc::fixup_sparc_lo10:  return ELF::R_SPARC_LO10;
   case Sparc::fixup_sparc_h44:   return ELF::R_SPARC_H44;
@@ -88,6 +89,7 @@ unsigned SparcELFObjectWriter::getRelocType(MCContext &Ctx,
   case Sparc::fixup_sparc_hm:    return ELF::R_SPARC_HM10;
   case Sparc::fixup_sparc_got22: return ELF::R_SPARC_GOT22;
   case Sparc::fixup_sparc_got10: return ELF::R_SPARC_GOT10;
+  case Sparc::fixup_sparc_got13: return ELF::R_SPARC_GOT13;
   case Sparc::fixup_sparc_tls_gd_hi22:   return ELF::R_SPARC_TLS_GD_HI22;
   case Sparc::fixup_sparc_tls_gd_lo10:   return ELF::R_SPARC_TLS_GD_LO10;
   case Sparc::fixup_sparc_tls_gd_add:    return ELF::R_SPARC_TLS_GD_ADD;
diff --git a/llvm/lib/Target/Sparc/MCTargetDesc/SparcFixupKinds.h b/llvm/lib/Target/Sparc/MCTargetDesc/SparcFixupKinds.h
index 8d79396d936..99aa63fe229 100644
--- a/llvm/lib/Target/Sparc/MCTargetDesc/SparcFixupKinds.h
+++ b/llvm/lib/Target/Sparc/MCTargetDesc/SparcFixupKinds.h
@@ -30,6 +30,9 @@ namespace llvm {
       fixup_sparc_br16_2,
       fixup_sparc_br16_14,
 
+      /// fixup_sparc_13 - 13-bit fixup
+      fixup_sparc_13,
+
       /// fixup_sparc_hi22  - 22-bit fixup corresponding to %hi(foo)
       /// for sethi
       fixup_sparc_hi22,
@@ -64,6 +67,9 @@ namespace llvm {
       /// fixup_sparc_got10 - 10-bit fixup corresponding to %got10(foo)
       fixup_sparc_got10,
 
+      /// fixup_sparc_got13 - 13-bit fixup corresponding to %got13(foo)
+      fixup_sparc_got13,
+
       /// fixup_sparc_wplt30
       fixup_sparc_wplt30,
 
diff --git a/llvm/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.cpp b/llvm/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.cpp
index 2b80293df12..f736a37a266 100644
--- a/llvm/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.cpp
+++ b/llvm/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.cpp
@@ -58,6 +58,8 @@ bool SparcMCExpr::printVariantKind(raw_ostream &OS, VariantKind Kind)
     // FIXME: use %got22/%got10, if system assembler supports them.
   case VK_Sparc_GOT22:    OS << "%hi("; break;
   case VK_Sparc_GOT10:    OS << "%lo("; break;
+  case VK_Sparc_GOT13:    closeParen = false; break;
+  case VK_Sparc_13:       closeParen = false; break;
   case VK_Sparc_WPLT30:   closeParen = false; break;
   case VK_Sparc_R_DISP32: OS << "%r_disp32("; break;
   case VK_Sparc_TLS_GD_HI22:   OS << "%tgd_hi22(";   break;
@@ -96,6 +98,7 @@ SparcMCExpr::VariantKind SparcMCExpr::parseVariantKind(StringRef name)
     .Case("pc10",  VK_Sparc_PC10)
     .Case("got22", VK_Sparc_GOT22)
     .Case("got10", VK_Sparc_GOT10)
+    .Case("got13", VK_Sparc_GOT13)
     .Case("r_disp32",   VK_Sparc_R_DISP32)
     .Case("tgd_hi22",   VK_Sparc_TLS_GD_HI22)
     .Case("tgd_lo10",   VK_Sparc_TLS_GD_LO10)
@@ -132,6 +135,8 @@ Sparc::Fixups SparcMCExpr::getFixupKind(SparcMCExpr::VariantKind Kind) {
   case VK_Sparc_PC10:     return Sparc::fixup_sparc_pc10;
   case VK_Sparc_GOT22:    return Sparc::fixup_sparc_got22;
   case VK_Sparc_GOT10:    return Sparc::fixup_sparc_got10;
+  case VK_Sparc_GOT13:    return Sparc::fixup_sparc_got13;
+  case VK_Sparc_13:       return Sparc::fixup_sparc_13;
   case VK_Sparc_WPLT30:   return Sparc::fixup_sparc_wplt30;
   case VK_Sparc_TLS_GD_HI22:   return Sparc::fixup_sparc_tls_gd_hi22;
   case VK_Sparc_TLS_GD_LO10:   return Sparc::fixup_sparc_tls_gd_lo10;
diff --git a/llvm/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.h b/llvm/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.h
index 13f08195c76..cf2db067749 100644
--- a/llvm/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.h
+++ b/llvm/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.h
@@ -36,6 +36,8 @@ public:
     VK_Sparc_PC10,
     VK_Sparc_GOT22,
     VK_Sparc_GOT10,
+    VK_Sparc_GOT13,
+    VK_Sparc_13,
     VK_Sparc_WPLT30,
     VK_Sparc_R_DISP32,
     VK_Sparc_TLS_GD_HI22,
diff --git a/llvm/lib/Target/Sparc/SparcISelLowering.cpp b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
index 34e0297fe9f..14a99c085f8 100644
--- a/llvm/lib/Target/Sparc/SparcISelLowering.cpp
+++ b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
@@ -1980,11 +1980,22 @@ SDValue SparcTargetLowering::makeAddress(SDValue Op, SelectionDAG &DAG) const {
 
   // Handle PIC mode first. SPARC needs a got load for every variable!
   if (isPositionIndependent()) {
-    // This is the pic32 code model, the GOT is known to be smaller than 4GB.
-    SDValue HiLo = makeHiLoPair(Op, SparcMCExpr::VK_Sparc_GOT22,
-                                SparcMCExpr::VK_Sparc_GOT10, DAG);
+    const Module *M = DAG.getMachineFunction().getFunction().getParent();
+    PICLevel::Level picLevel = M->getPICLevel();
+    SDValue Idx;
+
+    if (picLevel == PICLevel::SmallPIC) {
+      // This is the pic13 code model, the GOT is known to be smaller than 8KiB.
+      Idx = DAG.getNode(SPISD::Lo, DL, Op.getValueType(),
+                        withTargetFlags(Op, SparcMCExpr::VK_Sparc_GOT13, DAG));
+    } else {
+      // This is the pic32 code model, the GOT is known to be smaller than 4GB.
+      Idx = makeHiLoPair(Op, SparcMCExpr::VK_Sparc_GOT22,
+                         SparcMCExpr::VK_Sparc_GOT10, DAG);
+    }
+
     SDValue GlobalBase = DAG.getNode(SPISD::GLOBAL_BASE_REG, DL, VT);
-    SDValue AbsAddr = DAG.getNode(ISD::ADD, DL, VT, GlobalBase, HiLo);
+    SDValue AbsAddr = DAG.getNode(ISD::ADD, DL, VT, GlobalBase, Idx);
     // GLOBAL_BASE_REG codegen'ed with call. Inform MFI that this
     // function has calls.
     MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();