[PowerPC] Fix incorrect PC Relative relocations for Big Endian

[stefanp]

Summary

Fix the incorrect PC Relative relocations for Big Endian for 34 bit offsets.
The offset should be zero for both BE and LE in this situation.

[NeHuang]

LGTM.

[sfertile]

LGTM.

Minor nit not related to this patch is that the test is really noisy. I realize this is the assembly clang emits, but a lit test can be cleaned up to just the needed constructs. Removing the comments, zero padding after the functions, local aliases (.Lexternal$local) and finally the size directives and the labels that are only needed for those directives goes along way in creating a much simpler test that helps to highlight exactly what functionality is being exercised at a glance. After landing this patch can you do an NFC cleanup of the test?

[stefanp]

In D81033#2076897, @sfertile wrote:

After landing this patch can you do an NFC cleanup of the test?

Yes, I can certainly do that!

llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp

 PPCMCCodeEmitter::getImm34Encoding(const MCInst &MI, unsigned OpNo,
                                    SmallVectorImpl<MCFixup> &Fixups,
                                    const MCSubtargetInfo &STI) const {
   const MCOperand &MO = MI.getOperand(OpNo);
   if (MO.isReg() || MO.isImm())
     return getMachineOpValue(MI, MO, Fixups, STI);
 
   // Add a fixup for the immediate field.
-  Fixups.push_back(MCFixup::create(IsLittleEndian? 0 : 1, MO.getExpr(),
+  Fixups.push_back(MCFixup::create(0, MO.getExpr(),
                                    (MCFixupKind)PPC::fixup_ppc_pcrel34));
   return 0;
 }
 
 unsigned PPCMCCodeEmitter::getMemRIEncoding(const MCInst &MI, unsigned OpNo,
                                             SmallVectorImpl<MCFixup> &Fixups,
                                             const MCSubtargetInfo &STI) const {
   // Encode (imm, reg) as a memri, which has the low 16-bits as the
case MCExpr::SymbolRef: {
     const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(Expr);
     (void)SRE;
     // Currently these are the only valid PCRelative Relocations.
     assert((SRE->getKind() == MCSymbolRefExpr::VK_PCREL ||
             SRE->getKind() == MCSymbolRefExpr::VK_PPC_GOT_PCREL) &&
            "VariantKind must be VK_PCREL or VK_PPC_GOT_PCREL");
     // Generate the fixup for the relocation.
     Fixups.push_back(
-        MCFixup::create(IsLittleEndian ? 0 : 1, Expr,
+        MCFixup::create(0, Expr,
                         static_cast<MCFixupKind>(PPC::fixup_ppc_pcrel34)));
     // There is no offset to return so just return 0.
     return 0;
   }
   case MCExpr::Binary: {
     // Relocation plus some offset.
     const MCBinaryExpr *BE = cast<MCBinaryExpr>(Expr);
     assert(BE->getOpcode() == MCBinaryExpr::Add &&
case MCExpr::Binary: {
     const MCConstantExpr *CE = cast<MCConstantExpr>(RHS);
 
     // Currently these are the only valid PCRelative Relocations.
     assert((SRE->getKind() == MCSymbolRefExpr::VK_PCREL ||
             SRE->getKind() == MCSymbolRefExpr::VK_PPC_GOT_PCREL) &&
            "VariantKind must be VK_PCREL or VK_PPC_GOT_PCREL");
     // Generate the fixup for the relocation.
     Fixups.push_back(
-        MCFixup::create(IsLittleEndian ? 0 : 1, Expr,
+        MCFixup::create(0, Expr,
                         static_cast<MCFixupKind>(PPC::fixup_ppc_pcrel34)));
     assert(isInt<34>(CE->getValue()) && "Value must fit in 34 bits.");
     // Return the offset that should be added to the relocation by the linker.
     return (CE->getValue() & 0x3FFFFFFFFUL) | RegBits;
     }
   }
 }
 

llvm/test/MC/PowerPC/future-reloc.s

 # RUN: llvm-mc -triple=powerpc64le-unknown-unknown -filetype=obj %s 2>&1 | \
 # RUN: FileCheck %s -check-prefix=MC
 # RUN: llvm-mc -triple=powerpc64le-unknown-unknown -filetype=obj %s | \
 # RUN: llvm-readobj -r | FileCheck %s -check-prefix=READOBJ
 
+# RUN: llvm-mc -triple=powerpc64-unknown-unknown -filetype=obj %s 2>&1 | \
+# RUN: FileCheck %s -check-prefix=MC
+# RUN: llvm-mc -triple=powerpc64-unknown-unknown -filetype=obj %s | \
+# RUN: llvm-readobj -r | FileCheck %s -check-prefix=READOBJ
+
 # This test checks that on Power PC we can correctly convert @pcrel and
 # @got@pcrel into R_PPC64_PCREL34 and R_PPC64_GOT_PCREL34.
 
 # MC-NOT:    error: invalid variant
 
 # READOBJ:        0x0 R_PPC64_PCREL34 locvalue 0x0
 # READOBJ-NEXT:   0x20 R_PPC64_GOT_PCREL34 evalue 0x0