serge-sans-paille marked 3 inline comments as done.
serge-sans-paille added inline comments.
================
Comment at: llvm/lib/Target/X86/X86FrameLowering.cpp:400
+ !(STI.isOSWindows() && !STI.isTargetMachO());
+ if (InlineStackClashProtector && !InEpilogue) {
+ const uint64_t PageSize = TLI.getStackProbeSize(MF);
----------------
efriedma wrote:
> Why is this code in a different location from the stack probing code that
> generates a call?
Because `BuildStackAdjustment` has more callsites than just emitPrologue and we
want to capture all stack manipulation.
================
Comment at: llvm/lib/Target/X86/X86FrameLowering.cpp:408
+ CurrentAbsOffset += ChunkSize;
+ MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead.
+
----------------
efriedma wrote:
> This algorithm needs some documentation; it isn't at all obvious what it's
> doing. Particularly the interaction with "free" stack probes.
>
> Should we generate a loop if the stack frame is large?
> Should we generate a loop if the stack frame is large?
That's an option. it's more complex to make looping compatible with free
probes, but that's possible.
================
Comment at: llvm/lib/Target/X86/X86FrameLowering.cpp:408
+ CurrentAbsOffset += ChunkSize;
+ MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead.
+
----------------
serge-sans-paille wrote:
> efriedma wrote:
> > This algorithm needs some documentation; it isn't at all obvious what it's
> > doing. Particularly the interaction with "free" stack probes.
> >
> > Should we generate a loop if the stack frame is large?
> > Should we generate a loop if the stack frame is large?
>
> That's an option. it's more complex to make looping compatible with free
> probes, but that's possible.
> This algorithm needs some documentation
Done
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D68720/new/
https://reviews.llvm.org/D68720
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