[X86] Fix x86-64 call *foo@tlsdesc(%rax) and support R_386_TLSGOTDESC R_386_TLS_DESC_CALL
D18885 emitted 5 bytes for call *foo@tlsdesc(%rax). It should use the
2-byte form instead and let R_X86_64_TLSDESC_CALL apply to the beginning
of the call instruction.
The 2-byte form was deliberately chosen to make ->LE and ->IE relaxation work:
0: 48 8d 05 00 00 00 00 lea 0x0(%rip),%rax # 7 <.text+0x7>
3: R_X86_64_GOTPC32_TLSDESC a-0x4
7: ff 10 callq *(%rax)
7: R_X86_64_TLSDESC_CALL a
=>
0: 48 c7 c0 fc ff ff ff mov $0xfffffffffffffffc,%rax
7: 66 90 xchg %ax,%ax
Also change the symbol type to STT_TLS when VK_TLSCALL or VK_TLSDESC is
seen.
Reviewed By: compnerd
Differential Revision: https://reviews.llvm.org/D62512
llvm-svn: 361910
diff --git a/llvm/lib/MC/MCELFStreamer.cpp b/llvm/lib/MC/MCELFStreamer.cpp
index 6fe16abd..245dd06 100644
--- a/llvm/lib/MC/MCELFStreamer.cpp
+++ b/llvm/lib/MC/MCELFStreamer.cpp
@@ -400,6 +400,8 @@
case MCSymbolRefExpr::VK_INDNTPOFF:
case MCSymbolRefExpr::VK_NTPOFF:
case MCSymbolRefExpr::VK_GOTNTPOFF:
+ case MCSymbolRefExpr::VK_TLSCALL:
+ case MCSymbolRefExpr::VK_TLSDESC:
case MCSymbolRefExpr::VK_TLSGD:
case MCSymbolRefExpr::VK_TLSLD:
case MCSymbolRefExpr::VK_TLSLDM:
diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86ELFObjectWriter.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86ELFObjectWriter.cpp
index e693983..232a065 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86ELFObjectWriter.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86ELFObjectWriter.cpp
@@ -271,6 +271,10 @@
assert(Type == RT32_32);
assert(!IsPCRel);
return ELF::R_386_GOTOFF;
+ case MCSymbolRefExpr::VK_TLSCALL:
+ return ELF::R_386_TLS_DESC_CALL;
+ case MCSymbolRefExpr::VK_TLSDESC:
+ return ELF::R_386_TLS_GOTDESC;
case MCSymbolRefExpr::VK_TPOFF:
assert(Type == RT32_32);
assert(!IsPCRel);
diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
index 8eb48fc..31d26d0 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
@@ -524,9 +524,23 @@
// indirect register encoding, this handles addresses like [EAX]. The
// encoding for [EBP] with no displacement means [disp32] so we handle it
// by emitting a displacement of 0 below.
- if (Disp.isImm() && Disp.getImm() == 0 && BaseRegNo != N86::EBP) {
- EmitByte(ModRMByte(0, RegOpcodeField, BaseRegNo), CurByte, OS);
- return;
+ if (BaseRegNo != N86::EBP) {
+ if (Disp.isImm() && Disp.getImm() == 0) {
+ EmitByte(ModRMByte(0, RegOpcodeField, BaseRegNo), CurByte, OS);
+ return;
+ }
+
+ // If the displacement is @tlscall, treat it as a zero.
+ if (Disp.isExpr()) {
+ auto *Sym = dyn_cast<MCSymbolRefExpr>(Disp.getExpr());
+ if (Sym && Sym->getKind() == MCSymbolRefExpr::VK_TLSCALL) {
+ // This is exclusively used by call *a@tlscall(base). The relocation
+ // (R_386_TLSCALL or R_X86_64_TLSCALL) applies to the beginning.
+ Fixups.push_back(MCFixup::create(0, Sym, FK_NONE, MI.getLoc()));
+ EmitByte(ModRMByte(0, RegOpcodeField, BaseRegNo), CurByte, OS);
+ return;
+ }
+ }
}
// Otherwise, if the displacement fits in a byte, encode as [REG+disp8].