From 3c0af35232d3efcf5a88ad3f44999c8e0e3c4616 Mon Sep 17 00:00:00 2001 From: Pete Cooper Date: Mon, 27 Oct 2014 19:40:35 +0000 Subject: Stackmap shadows should consider call returns a branch target. To avoid emitting too many nops, a stackmap shadow can include emitted instructions in the shadow, but these must not include branch targets. A return from a call should count as a branch target as patching over the instructions after the call would lead to incorrect behaviour for threads currently making that call, when they return. llvm-svn: 220710 --- llvm/lib/Target/X86/X86MCInstLower.cpp | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'llvm/lib/Target') diff --git a/llvm/lib/Target/X86/X86MCInstLower.cpp b/llvm/lib/Target/X86/X86MCInstLower.cpp index fc3662e6bec..85cf5144f0c 100644 --- a/llvm/lib/Target/X86/X86MCInstLower.cpp +++ b/llvm/lib/Target/X86/X86MCInstLower.cpp @@ -1210,4 +1210,10 @@ void X86AsmPrinter::EmitInstruction(const MachineInstr *MI) { MCInst TmpInst; MCInstLowering.Lower(MI, TmpInst); EmitAndCountInstruction(TmpInst); + + // Stackmap shadows cannot include branch targets, so we can count the bytes + // in a call towards the shadow, but must flush the shadow immediately after + // to account for the return from the call. + if (MI->isCall()) + SMShadowTracker.emitShadowPadding(OutStreamer, getSubtargetInfo()); } -- cgit v1.2.3