[patchpoint] Add support for symbolic patchpoint targets to SelectionDAG and the
X86 backend.
The code generated for symbolic targets is identical to the code generated for
constant targets, except that a relocation is emitted to fix up the actual
target address at link-time. This allows IR and object files containing
patchpoints to be cached across JIT-invocations where the target address may
change.
llvm-svn: 235483
diff --git a/llvm/lib/Target/X86/X86MCInstLower.cpp b/llvm/lib/Target/X86/X86MCInstLower.cpp
index cd3076d..98dc376 100644
--- a/llvm/lib/Target/X86/X86MCInstLower.cpp
+++ b/llvm/lib/Target/X86/X86MCInstLower.cpp
@@ -867,7 +867,8 @@
// Lower a patchpoint of the form:
// [<def>], <id>, <numBytes>, <target>, <numArgs>, <cc>, ...
-void X86AsmPrinter::LowerPATCHPOINT(const MachineInstr &MI) {
+void X86AsmPrinter::LowerPATCHPOINT(const MachineInstr &MI,
+ X86MCInstLower &MCIL) {
assert(Subtarget->is64Bit() && "Patchpoint currently only supports X86-64");
SMShadowTracker.emitShadowPadding(OutStreamer, getSubtargetInfo());
@@ -877,8 +878,29 @@
PatchPointOpers opers(&MI);
unsigned ScratchIdx = opers.getNextScratchIdx();
unsigned EncodedBytes = 0;
- int64_t CallTarget = opers.getMetaOper(PatchPointOpers::TargetPos).getImm();
- if (CallTarget) {
+ const MachineOperand &CalleeMO =
+ opers.getMetaOper(PatchPointOpers::TargetPos);
+
+ // Check for null target. If target is non-null (i.e. is non-zero or is
+ // symbolic) then emit a call.
+ if (!(CalleeMO.isImm() && !CalleeMO.getImm())) {
+ MCOperand CalleeMCOp;
+ switch (CalleeMO.getType()) {
+ default:
+ /// FIXME: Add a verifier check for bad callee types.
+ llvm_unreachable("Unrecognized callee operand type.");
+ case MachineOperand::MO_Immediate:
+ if (CalleeMO.getImm())
+ CalleeMCOp = MCOperand::CreateImm(CalleeMO.getImm());
+ break;
+ case MachineOperand::MO_ExternalSymbol:
+ case MachineOperand::MO_GlobalAddress:
+ CalleeMCOp =
+ MCIL.LowerSymbolOperand(CalleeMO,
+ MCIL.GetSymbolFromOperand(CalleeMO));
+ break;
+ }
+
// Emit MOV to materialize the target address and the CALL to target.
// This is encoded with 12-13 bytes, depending on which register is used.
unsigned ScratchReg = MI.getOperand(ScratchIdx).getReg();
@@ -886,10 +908,12 @@
EncodedBytes = 13;
else
EncodedBytes = 12;
- EmitAndCountInstruction(MCInstBuilder(X86::MOV64ri).addReg(ScratchReg)
- .addImm(CallTarget));
+
+ EmitAndCountInstruction(
+ MCInstBuilder(X86::MOV64ri).addReg(ScratchReg).addOperand(CalleeMCOp));
EmitAndCountInstruction(MCInstBuilder(X86::CALL64r).addReg(ScratchReg));
}
+
// Emit padding.
unsigned NumBytes = opers.getMetaOper(PatchPointOpers::NBytesPos).getImm();
assert(NumBytes >= EncodedBytes &&
@@ -1091,7 +1115,7 @@
return LowerSTACKMAP(*MI);
case TargetOpcode::PATCHPOINT:
- return LowerPATCHPOINT(*MI);
+ return LowerPATCHPOINT(*MI, MCInstLowering);
case X86::MORESTACK_RET:
EmitAndCountInstruction(MCInstBuilder(getRetOpcode(*Subtarget)));