ARM branch backwards with SYM_RESOLVER fails

[jan2642]

(I'm using thumb)

When using the SYM_RESOLVER to jump to a symbol at lower address, the result is the same as encoding 'bl #0'

The reason is that negative relative values cause IsResolved to be set to false in ARMAsmBackend::processFixupValue. The following patch fixes it for me:

index f64d51b..d843ea8 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
@@ -699,7 +699,7 @@ void ARMAsmBackend::processFixupValue(const MCAssembler &Asm,

     // If the symbol is out of range, produce a relocation and hope the
     // linker can handle it. GNU AS produces an error in this case.
-    if (Sym->isExternal() || Value >= 0x400004)
+    if (Sym->isExternal() || ((Value >= 0x400004) && (Value <= (uint64_t)(-0x400000))))
       IsResolved = false;
   }
   // We must always generate a relocation for BL/BLX instructions if we have```

[jan2642]

Just tried this on the master branch and this issue is still as valid as it was 18 months ago. Pull request #355 submitted over a year ago fixes it.