llvm dev - May 2020 - X86TargetLowering::EmitLoweredProbedAlloca()

Hi,

I am working on implementing stack clash protection for SystemZ 
(https://reviews.llvm.org/D78717), and have been studying how X86 does 
this. Looking at the implementation of EmitLoweredProbedAlloca(), it 
seems that the 'tail' is not probed. Doesn't this mean that multiple
small dynamic allocas could result in advancing the stack pointer past 
the guard page?

/Jonas

Yes.

-Eli

-----Original Message-----
From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of Jonas
Paulsson via llvm-dev
Sent: Friday, May 1, 2020 1:00 AM
To: Craig Topper <craig.topper at gmail.com>; sguelton at redhat.com
Cc: llvm-dev <llvm-dev at lists.llvm.org>; Ulrich Weigand
<ulrich.weigand at de.ibm.com>
Subject: [EXT] [llvm-dev] X86TargetLowering::EmitLoweredProbedAlloca()

Hi,

I am working on implementing stack clash protection for SystemZ
(https://reviews.llvm.org/D78717), and have been studying how X86 does
this. Looking at the implementation of EmitLoweredProbedAlloca(), it
seems that the 'tail' is not probed. Doesn't this mean that multiple
small dynamic allocas could result in advancing the stack pointer past
the guard page?

/Jonas


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