ARM: support R_ARM_THM_JUMP19 relocation in THM stubs

include/eld/Diagnostics/DiagRelocations.inc

@@ -30,7 +30,7 @@ DIAG(unknown_reloc_section_type, DiagnosticEngine::Unreachable,
      "unknown relocation section type: `%0' in section `%1'")
 DIAG(unsupport_cond_branch_reloc, DiagnosticEngine::Error,
      "applying relocation `%0', conditional branch to PLT in THUMB-2 not "
-     "supported yet")
+     "supported yet for symbol `%1' referred from %2[%3]")
 DIAG(copyrelocs_is_error, DiagnosticEngine::Error,
      "Cannot copy symbol %0 referenced in %1 from dynamic library %1 due to -z "
      "nocopyrelocs ")

include/eld/Driver/GnuLinkerOptions.td

@@ -225,6 +225,16 @@ defm Ttext_segment
                     "Specify an address for the .text-segment segment">,
       MetaVarName<"<address>">,
       Group<grp_scriptopts>;
+defm Trodata_segment
+    : dashEqWithOpt<"Trodata-segment", "Trodata-segment", "Trodata_segment",
+                    "Specify an address for the first byte of the read-only data segment">,
+      MetaVarName<"<address>">,
+      Group<grp_scriptopts>;
+defm Tldata_segment
+    : dashEqWithOpt<"Tldata-segment", "Tldata-segment", "Tldata_segment",
+                    "Specify an address for the first byte of the ldata segment">,
+      MetaVarName<"<address>">,
+      Group<grp_scriptopts>;
 defm Tdata
     : smDash<"Tdata", "Tdata", "Specify an address for the .data section">,
       MetaVarName<"<address>">,

lib/Target/ARM/ARMRelocator.cpp

@@ -667,6 +667,27 @@ void ARMRelocator::scanGlobalReloc(InputFile &pInput, Relocation::Type Type,
   case llvm::ELF::R_ARM_THM_JUMP11:
   case llvm::ELF::R_ARM_THM_JUMP8: {
     std::lock_guard<std::mutex> relocGuard(m_RelocMutex);
+
+    // Check if this symbol already has a PLT, or is about to be granted one
+    bool needsPLT = false;
+    if (rsym->reserved() & ReservePLT) {
+      needsPLT = true;
+    } else if ((rsym->type() == ResolveInfo::IndirectFunc) && config().isCodeStatic()) {
+      needsPLT = true;
+    } else if (getTarget().isSymbolPreemptible(*rsym) && rsym->visibility() != ResolveInfo::Hidden) {
+      needsPLT = true;
+    }
+
+    // If a PLT is involved and this is a JUMP19, throw our detailed error immediately!
+    if (needsPLT && pReloc.type() == llvm::ELF::R_ARM_THM_JUMP19) {
+      config().raise(Diag::unsupport_cond_branch_reloc)
+          << (int)pReloc.type() 
+          << rsym->name() 
+          << pReloc.getSourcePath(config().options()) 
+          << pSection.name();
+      return;
+    }
+
     // These are branch relocation (except PREL31)
     // A PLT entry is needed when building shared library
 
@@ -1100,12 +1121,6 @@ Relocator::Result thm_jump19(Relocation &pReloc, ARMRelocator &pParent) {
       helper_clear_thumb_bit(S);
   }
 
-  if (0x0 == T) {
-    // FIXME: conditional branch to PLT in THUMB-2 not supported yet
-    DiagEngine->raise(Diag::unsupport_cond_branch_reloc) << (int)pReloc.type();
-    return Relocator::BadReloc;
-  }
-
   Relocator::DWord X = ((S + A) | T) - P;
   int32_t SignedValue = static_cast<int32_t>(X);
   if (!llvm::isInt<21>(SignedValue))

lib/Target/ARM/THMToARMStub.cpp

@@ -89,7 +89,8 @@ bool THMToARMStub::isNeeded(const Relocation *pReloc, int64_t pTargetValue,
       !(pReloc->symInfo()->reserved() & Relocator::ReservePLT))
     return false;
   // always need a stub to switch mode for JUMp24
-  if (pReloc->type() == llvm::ELF::R_ARM_THM_JUMP24) {
+  if (pReloc->type() == llvm::ELF::R_ARM_THM_JUMP24 || 
+      pReloc->type() == llvm::ELF::R_ARM_THM_JUMP19) {
     return true;
   }
   // Other relocation needs stub only if it cannot reach
@@ -104,11 +105,13 @@ bool THMToARMStub::isRelocInRange(const class Relocation *pReloc,
   Offset = pTargetValue + addend - pReloc->place(Module);
   switch (pReloc->type()) {
   case llvm::ELF::R_ARM_THM_JUMP24:
-  case llvm::ELF::R_ARM_THM_CALL: {
+  case llvm::ELF::R_ARM_THM_CALL:{
     if (m_Target->isJ1J2BranchEncoding())
       return llvm::isInt<THM2_MAX_BRANCH_BITS>(Offset);
     return llvm::isInt<THM_MAX_BRANCH_BITS>(Offset);
   }
+  case llvm::ELF::R_ARM_THM_JUMP19:
+    return llvm::isInt<21>(Offset);
   default:
     break;
   }

lib/Target/ARM/THMToTHMStub.cpp

@@ -92,7 +92,9 @@ bool THMToTHMStub::isNeeded(const Relocation *pReloc, int64_t pTargetValue,
                             Module &Module) const {
   int64_t Offset = 0;
   // This stub cannot be used for ARM target.
-  if ((pTargetValue & 0x1) == 0)
+  if ((pTargetValue & 0x1) == 0 &&
+       pReloc->type() != llvm::ELF::R_ARM_THM_JUMP19 &&
+       pReloc->type() != llvm::ELF::R_ARM_THM_JUMP24)
     return false;
   // The stub is needed only if the target is unreachable
   return !isRelocInRange(pReloc, pTargetValue, Offset, Module);
@@ -107,11 +109,13 @@ bool THMToTHMStub::isRelocInRange(const Relocation *pReloc,
   Offset = pTargetValue + addend - pReloc->place(Module);
   switch (pReloc->type()) {
   case llvm::ELF::R_ARM_THM_JUMP24:
-  case llvm::ELF::R_ARM_THM_CALL: {
+  case llvm::ELF::R_ARM_THM_CALL:{
     if (m_Target->isJ1J2BranchEncoding())
       return llvm::isInt<THM2_MAX_BRANCH_BITS>(Offset);
     return llvm::isInt<THM_MAX_BRANCH_BITS>(Offset);
   }
+  case llvm::ELF::R_ARM_THM_JUMP19:
+    return llvm::isInt<21>(Offset);
   default:
     break;
   }

test/ARM/standalone/THMJump19Veneer/thm-jump19-basic.s

@@ -0,0 +1,30 @@
+// Tests that R_ARM_THM_JUMP19 (conditional branch) links successfully
+// for an in-range target without requiring a stub.
+// Regression test for https://github.com/qualcomm/eld/issues/1005
+
+// RUN: %clang %clangopts %s -o %t.o -c --target=arm-none-eabi -mcpu=cortex-m33 -mfloat-abi=soft
+// RUN: %link %linkopts %t.o -o %t.out --entry=my_func -static
+// RUN: %objdump -d %t.out | %filecheck %s
+
+// CHECK: <my_func>:
+// CHECK:      {{.*}} beq.w   {{.*}} <plain_entry>
+
+// CHECK: <plain_entry>:
+// CHECK-NEXT: {{.*}} bx      lr
+
+    .syntax unified
+    .thumb
+
+    .section .text.caller, "ax", %progbits
+    .thumb_func
+    .global my_func
+    .type   my_func, %function
+my_func:
+    cmp  r0, #0
+    beq  plain_entry
+    bx   lr
+
+    .section .text.target, "ax", %progbits
+    .global plain_entry
+plain_entry:
+    bx   lr

test/ARM/standalone/THMJump19Veneer/thm-jump19-plt-diag.s

@@ -0,0 +1,22 @@
+// Tests that R_ARM_THM_JUMP19 correctly emits a detailed error 
+// when attempting to branch to a PLT entry.
+// Regression test for https://github.com/qualcomm/eld/issues/1005
+
+// RUN: %clang %clangopts %s -o %t.o -c --target=arm-none-eabi -march=armv7-a
+// RUN: not %link %linkopts -shared %t.o -o %t.so 2>&1 | %filecheck %s
+
+// CHECK: Error:
+// CHECK-SAME: conditional branch to PLT in THUMB-2 not supported yet for symbol `extern_func'
+// CHECK-SAME: [.text.caller][.text.caller]
+
+    .syntax unified
+    .thumb
+
+    .section .text.caller, "ax", %progbits
+    .thumb_func
+    .global my_func
+    .type   my_func, %function
+my_func:
+    cmp  r0, #0
+    beq  extern_func  // Conditional branch to an undefined external symbol
+    bx   lr

test/ARM/standalone/THMJump19Veneer/thm-jump19-veneer.s

@@ -0,0 +1,41 @@
+// Tests that R_ARM_THM_JUMP19 (conditional branch) produces both T2T and T2A veneers
+// when the targets are out of range (beyond 21-bit range).
+// Regression test for https://github.com/qualcomm/eld/issues/1005
+
+// RUN: %clang %clangopts %s -o %t.o -c --target=arm-none-eabi -march=armv7-a -mfloat-abi=soft
+// RUN: echo "SECTIONS { .text.caller 0x0 : { *(.text.caller) } .text.thumb_target 0x200000 : { *(.text.thumb_target) } .text.arm_target 0x400000 : { *(.text.arm_target) } }" > %t.script
+// RUN: %link %linkopts -T %t.script %t.o -o %t.out --entry=my_func -static --trace=trampolines 2>&1 | %filecheck %s
+
+// CHECK: Creating Stub __thumb_target_{{.*}}veneer@island-{{.*}}
+// CHECK: Creating Stub __arm_target_{{.*}}veneer@island-{{.*}}
+
+.syntax unified
+
+// --- CALLER (Thumb) ---
+.section .text.caller, "ax", %progbits
+.thumb
+.thumb_func
+.global my_func
+.type   my_func, %function
+my_func:
+    cmp  r0, #0
+    beq  thumb_target   // Triggers T2T Veneer
+    beq  arm_target     // Triggers T2A Veneer
+    bx   lr
+
+// --- TARGET 1 (Thumb) ---
+.section .text.thumb_target, "ax", %progbits
+.thumb
+.thumb_func
+.global thumb_target
+.type thumb_target, %function
+thumb_target:
+    bx   lr
+
+// --- TARGET 2 (ARM) ---
+.section .text.arm_target, "ax", %progbits
+.arm
+.global arm_target
+.type arm_target, %function
+arm_target:
+    bx   lr