ARM: add support for segment base relocations (SBREL)

This adds support for parsing and emitting the SBREL relocation variant for the
ARM target.  Handling this relocation variant is necessary for supporting the
full ARM ELF specification.  Addresses PR22128.

llvm-svn: 225595

diff --git a/llvm/include/llvm/MC/MCExpr.h b/llvm/include/llvm/MC/MCExpr.h
index f0e8611..bd9b2bc 100644 (file)
--- a/llvm/include/llvm/MC/MCExpr.h
+++ b/llvm/include/llvm/MC/MCExpr.h
@@ -194,6 +194,7 @@ public:
     VK_ARM_TARGET1,
     VK_ARM_TARGET2,
     VK_ARM_PREL31,
+    VK_ARM_SBREL,          // symbol(sbrel)
     VK_ARM_TLSLDO,         // symbol(tlsldo)
     VK_ARM_TLSCALL,        // symbol(tlscall)
     VK_ARM_TLSDESC,        // symbol(tlsdesc)

diff --git a/llvm/lib/MC/MCExpr.cpp b/llvm/lib/MC/MCExpr.cpp
index a1b0236..709dc6b 100644 (file)
--- a/llvm/lib/MC/MCExpr.cpp
+++ b/llvm/lib/MC/MCExpr.cpp
@@ -197,6 +197,7 @@ StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
   case VK_ARM_TARGET1: return "target1";
   case VK_ARM_TARGET2: return "target2";
   case VK_ARM_PREL31: return "prel31";
+  case VK_ARM_SBREL: return "sbrel";
   case VK_ARM_TLSLDO: return "tlsldo";
   case VK_ARM_TLSCALL: return "tlscall";
   case VK_ARM_TLSDESC: return "tlsdesc";
@@ -364,6 +365,7 @@ MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
     .Case("target1", VK_ARM_TARGET1)
     .Case("target2", VK_ARM_TARGET2)
     .Case("prel31", VK_ARM_PREL31)
+    .Case("sbrel", VK_ARM_SBREL)
     .Case("tlsldo", VK_ARM_TLSLDO)
     .Case("tlscall", VK_ARM_TLSCALL)
     .Case("tlsdesc", VK_ARM_TLSDESC)

diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
index c7739b4..a821a6b 100644 (file)
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
@@ -200,6 +200,9 @@ unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
       case MCSymbolRefExpr::VK_ARM_PREL31:
         Type = ELF::R_ARM_PREL31;
         break;
+      case MCSymbolRefExpr::VK_ARM_SBREL:
+        Type = ELF::R_ARM_SBREL32;
+        break;
       case MCSymbolRefExpr::VK_ARM_TLSLDO:
         Type = ELF::R_ARM_TLS_LDO32;
         break;

diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
index f940306..99b5c62 100644 (file)
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
@@ -553,6 +553,10 @@ public:
   /// necessary.
   void EmitValueImpl(const MCExpr *Value, unsigned Size,
                      const SMLoc &Loc) override {
+    if (const MCSymbolRefExpr *SRE = dyn_cast_or_null<MCSymbolRefExpr>(Value))
+      if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_SBREL && !(Size == 4))
+        getContext().FatalError(Loc, "relocated expression must be 32-bit");
+
     EmitDataMappingSymbol();
     MCELFStreamer::EmitValueImpl(Value, Size);
   }

diff --git a/llvm/test/MC/ARM/arm-elf-relocation-diagnostics.s b/llvm/test/MC/ARM/arm-elf-relocation-diagnostics.s
new file mode 100644 (file)
index 0000000..5fe903f
--- /dev/null
+++ b/llvm/test/MC/ARM/arm-elf-relocation-diagnostics.s
@@ -0,0 +1,27 @@
+@ RUN: not llvm-mc -triple armv7-eabi -filetype obj -o - %s 2>&1 \
+@ RUN:     | FileCheck %s
+@ RUN: not llvm-mc -triple thumbv7-eabi -filetype obj -o - %s 2>&1 \
+@ RUN:     | FileCheck %s
+
+       .byte target(sbrel)
+@ CHECK: error: relocated expression must be 32-bit
+@ CHECK: .byte target(sbrel)
+@ CHECK:       ^
+
+@ TODO: enable these negative test cases
+@      .hword target(sbrel)
+@ @ CHECK-SBREL-HWORD: error: relocated expression must be 32-bit
+@ @ CHECK-SBREL-HWORD: .hword target(sbrel)
+@ @ CHECK-SBREL-HWORD:        ^
+@
+@      .short target(sbrel)
+@ @ CHECK-SBREL-SHORT: error: relocated expression must be 32-bit
+@ @ CHECK-SBREL-SHORT: .short target(sbrel)
+@ @ CHECK-SBREL-SHORT:        ^
+@
+@      .quad target(sbrel)
+@ @ CHECK-SBREL-SHORT: error: relocated expression must be 32-bit
+@ @ CHECK-SBREL-SHORT: .quad target(sbrel)
+@ @ CHECK-SBREL-SHORT:        ^
+
+

diff --git a/llvm/test/MC/ARM/arm-elf-relocations.s b/llvm/test/MC/ARM/arm-elf-relocations.s
index 13d9d2b..4059591 100644 (file)
--- a/llvm/test/MC/ARM/arm-elf-relocations.s
+++ b/llvm/test/MC/ARM/arm-elf-relocations.s
@@ -25,3 +25,13 @@
 @ CHECK:   0x2 R_ARM_ABS16 abs16_1 0x0
 @ CHECK: }
 
+       .section .text.r_arm_sbrel32
+
+       .word target(sbrel)
+       .word target(SBREL)
+
+@ CHECK: Section {{.*}} .rel.text.r_arm_sbrel32 {
+@ CHECK:   0x0 R_ARM_SBREL32 target 0x0
+@ CHECK:   0x4 R_ARM_SBREL32 target 0x0
+@ CHECK: }
+