MC/X86: Lower TAILCALLd[64] to JMP_1, to allow relaxation and to avoid same
prefix byte problem as in r104062.
- As a total hack to keep the TAILCALL markers in the output, which some tests depend on, this invents a new TAILJMP_1 instruction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104120 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/AsmPrinter/X86MCInstLower.cpp b/lib/Target/X86/AsmPrinter/X86MCInstLower.cpp
index ec90fd6..4edeca9 100644
--- a/lib/Target/X86/AsmPrinter/X86MCInstLower.cpp
+++ b/lib/Target/X86/AsmPrinter/X86MCInstLower.cpp
@@ -379,6 +379,16 @@
break;
}
+ // TAILJMPd, TAILJMPd64 - Lower to the correct jump instructions.
+ case X86::TAILJMPd:
+ case X86::TAILJMPd64: {
+ MCOperand Saved = OutMI.getOperand(0);
+ OutMI = MCInst();
+ OutMI.setOpcode(X86::TAILJMP_1);
+ OutMI.addOperand(Saved);
+ break;
+ }
+
// The assembler backend wants to see branches in their small form and relax
// them to their large form. The JIT can only handle the large form because
// it does not do relaxation. For now, translate the large form to the
diff --git a/lib/Target/X86/X86InstrInfo.td b/lib/Target/X86/X86InstrInfo.td
index 818ccb0..a767b54 100644
--- a/lib/Target/X86/X86InstrInfo.td
+++ b/lib/Target/X86/X86InstrInfo.td
@@ -712,6 +712,13 @@
let mayLoad = 1 in
def TAILJMPm : I<0xFF, MRM4m, (outs), (ins i32mem_TC:$dst, variable_ops),
"jmp{l}\t{*}$dst # TAILCALL", []>;
+
+ // FIXME: This is a hack so that MCInst lowering can preserve the TAILCALL
+ // marker on instructions, while still being able to relax.
+ let isCodeGenOnly = 1 in {
+ def TAILJMP_1 : Ii8PCRel<0xEB, RawFrm, (outs), (ins brtarget8:$dst),
+ "jmp\t$dst # TAILCALL", []>;
+ }
}
//===----------------------------------------------------------------------===//