[PowerPC] Fix PR 21652 - copy st_other bits on symbol assignment

When processing an assignment in the integrated assembler that sets
a symbol to the value of another symbol, we need to copy the st_other
bits that encode the local entry point offset.

Modeled after MipsTargetELFStreamer::emitAssignment handling of the
ELF::STO_MIPS_MICROMIPS flag.

llvm-svn: 222672

1 files changed, 17 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
index 00be8f444d3..f2da3896168 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
@@ -184,6 +184,23 @@ public:
     if ((Flags & ELF::EF_PPC64_ABI) == 0)
       MCA.setELFHeaderEFlags(Flags | 2);
   }
+  void emitAssignment(MCSymbol *Symbol, const MCExpr *Value) override {
+    // When encoding an assignment to set symbol A to symbol B, also copy
+    // the st_other bits encoding the local entry point offset.
+    if (Value->getKind() != MCExpr::SymbolRef)
+      return;
+    const MCSymbol &RhsSym =
+        static_cast<const MCSymbolRefExpr *>(Value)->getSymbol();
+    MCSymbolData &Data = getStreamer().getOrCreateSymbolData(&RhsSym);
+    MCSymbolData &SymbolData = getStreamer().getOrCreateSymbolData(Symbol);
+    // The "other" values are stored in the last 6 bits of the second byte.
+    // The traditional defines for STO values assume the full byte and thus
+    // the shift to pack it.
+    unsigned Other = MCELF::getOther(SymbolData) << 2;
+    Other &= ~ELF::STO_PPC64_LOCAL_MASK;
+    Other |= (MCELF::getOther(Data) << 2) & ELF::STO_PPC64_LOCAL_MASK;
+    MCELF::setOther(SymbolData, Other >> 2);
+  }
 };
 
 class PPCTargetMachOStreamer : public PPCTargetStreamer {