Add implicit null and stack checks for x86
This adds compiler and runtime changes for x86
implicit checks. 32 bit only.
Both host and target are supported.
By default, on the host, the implicit checks are null pointer and
stack overflow. Suspend is implemented but not switched on.
Change-Id: I88a609e98d6bf32f283eaa4e6ec8bbf8dc1df78a
diff --git a/compiler/dex/quick/x86/call_x86.cc b/compiler/dex/quick/x86/call_x86.cc
index 9000514..916198d 100644
--- a/compiler/dex/quick/x86/call_x86.cc
+++ b/compiler/dex/quick/x86/call_x86.cc
@@ -222,15 +222,27 @@
LockTemp(rs_rX86_ARG1);
LockTemp(rs_rX86_ARG2);
- /* Build frame, return address already on stack */
- stack_decrement_ = OpRegImm(kOpSub, rs_rX86_SP, frame_size_ - GetInstructionSetPointerSize(cu_->instruction_set));
-
/*
* We can safely skip the stack overflow check if we're
* a leaf *and* our frame size < fudge factor.
*/
- const bool skip_overflow_check = mir_graph_->MethodIsLeaf() &&
- !IsLargeFrame(frame_size_, cu_->target64 ? kX86_64 : kX86);
+ InstructionSet isa = cu_->target64 ? kX86_64 : kX86;
+ const bool skip_overflow_check = mir_graph_->MethodIsLeaf() && !IsLargeFrame(frame_size_, isa);
+
+ // If we doing an implicit stack overflow check, perform the load immediately
+ // before the stack pointer is decremented and anything is saved.
+ if (!skip_overflow_check && !Runtime::Current()->ExplicitStackOverflowChecks()) {
+ // Implicit stack overflow check.
+ // test eax,[esp + -overflow]
+ int overflow = GetStackOverflowReservedBytes(isa);
+ NewLIR3(kX86Test32RM, rs_rAX.GetReg(), rs_rX86_SP.GetReg(), -overflow);
+ MarkPossibleStackOverflowException();
+ }
+
+ /* Build frame, return address already on stack */
+ stack_decrement_ = OpRegImm(kOpSub, rs_rX86_SP, frame_size_ -
+ GetInstructionSetPointerSize(cu_->instruction_set));
+
NewLIR0(kPseudoMethodEntry);
/* Spill core callee saves */
SpillCoreRegs();
@@ -261,25 +273,27 @@
private:
const size_t sp_displace_;
};
- // TODO: for large frames we should do something like:
- // spill ebp
- // lea ebp, [esp + frame_size]
- // cmp ebp, fs:[stack_end_]
- // jcc stack_overflow_exception
- // mov esp, ebp
- // in case a signal comes in that's not using an alternate signal stack and the large frame may
- // have moved us outside of the reserved area at the end of the stack.
- // cmp rs_rX86_SP, fs:[stack_end_]; jcc throw_slowpath
- if (cu_->target64) {
- OpRegThreadMem(kOpCmp, rs_rX86_SP, Thread::StackEndOffset<8>());
- } else {
- OpRegThreadMem(kOpCmp, rs_rX86_SP, Thread::StackEndOffset<4>());
- }
- LIR* branch = OpCondBranch(kCondUlt, nullptr);
- AddSlowPath(
+ if (Runtime::Current()->ExplicitStackOverflowChecks()) {
+ // TODO: for large frames we should do something like:
+ // spill ebp
+ // lea ebp, [esp + frame_size]
+ // cmp ebp, fs:[stack_end_]
+ // jcc stack_overflow_exception
+ // mov esp, ebp
+ // in case a signal comes in that's not using an alternate signal stack and the large frame
+ // may have moved us outside of the reserved area at the end of the stack.
+ // cmp rs_rX86_SP, fs:[stack_end_]; jcc throw_slowpath
+ if (cu_->target64) {
+ OpRegThreadMem(kOpCmp, rs_rX86_SP, Thread::StackEndOffset<8>());
+ } else {
+ OpRegThreadMem(kOpCmp, rs_rX86_SP, Thread::StackEndOffset<4>());
+ }
+ LIR* branch = OpCondBranch(kCondUlt, nullptr);
+ AddSlowPath(
new(arena_)StackOverflowSlowPath(this, branch,
frame_size_ -
GetInstructionSetPointerSize(cu_->instruction_set)));
+ }
}
FlushIns(ArgLocs, rl_method);
@@ -318,4 +332,14 @@
NewLIR0(kX86Ret);
}
+void X86Mir2Lir::GenImplicitNullCheck(RegStorage reg, int opt_flags) {
+ if (!(cu_->disable_opt & (1 << kNullCheckElimination)) && (opt_flags & MIR_IGNORE_NULL_CHECK)) {
+ return;
+ }
+ // Implicit null pointer check.
+ // test eax,[arg1+0]
+ NewLIR3(kX86Test32RM, rs_rAX.GetReg(), reg.GetReg(), 0);
+ MarkPossibleNullPointerException(opt_flags);
+}
+
} // namespace art