[ARM] Create relocations for unconditional branches.

Summary:
Relocations are required for unconditional branches to function symbols with
different execution mode. Without this patch, incorrect branches are
generated for tail calls between functions with different execution
mode.


Reviewers: peter.smith, rafael, echristo, kristof.beyls

Reviewed By: peter.smith

Subscribers: aemerson, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D33898

llvm-svn: 304882

1 files changed, 12 insertions, 7 deletions

diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
index 97e15be649e..546601e09dd 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
@@ -748,13 +748,18 @@ void ARMAsmBackend::processFixupValue(const MCAssembler &Asm,
     // linker can handle it. GNU AS produces an error in this case.
     if (Sym->isExternal() || Value >= 0x400004)
       IsResolved = false;
-    // When an ARM function is called from a Thumb function, produce a
-    // relocation so the linker will use the correct branch instruction for ELF
-    // binaries.
-    if (Sym->isELF()) {
-      unsigned Type = dyn_cast<MCSymbolELF>(Sym)->getType();
-      if ((Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC) &&
-          !Asm.isThumbFunc(Sym))
+  }
+  // Create relocations for unconditional branches to function symbols with
+  // different execution mode in ELF binaries.
+  if (Sym && Sym->isELF()) {
+    unsigned Type = dyn_cast<MCSymbolELF>(Sym)->getType();
+    if ((Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC)) {
+      unsigned FixupKind = Fixup.getKind() ;
+      if (Asm.isThumbFunc(Sym) && (FixupKind == ARM::fixup_arm_uncondbranch))
+        IsResolved = false;
+      if (!Asm.isThumbFunc(Sym) && (FixupKind == ARM::fixup_arm_thumb_br ||
+                                    FixupKind == ARM::fixup_arm_thumb_bl ||
+                                    FixupKind == ARM::fixup_t2_uncondbranch))
         IsResolved = false;
     }
   }