[llvm-dev] [cfe-dev] Call frame information query

Robinson, Paul via llvm-dev llvm-dev at lists.llvm.org
Mon Sep 25 11:28:41 PDT 2017

+ llvm-dev

It sounds like you are more interested in how to generate CFI instructions for your architecture.  It is often instructive to look at how other architectures handle this, as a model for new architectures.  I am not familiar with that area myself.

From: Siddharth Shankar Swain [mailto:h2015096 at pilani.bits-pilani.ac.in]
Sent: Monday, September 25, 2017 11:06 AM
To: Robinson, Paul; Clang Dev
Subject: Re: [cfe-dev] Call frame information query

Thanks for reply. We have FP, SP ready for a particular architecture. We want to know how CFI instructions give information to the debugger abut the machine registers and the stack frame as a whole. ? Please guide

On Mon, Sep 25, 2017 at 10:42 PM, Robinson, Paul <paul.robinson at sony.com<mailto:paul.robinson at sony.com>> wrote:
You are asking on cfe-dev but Clang does not emit these directly.  LLVM generates them.
DWARF CFI is used to inform the debugger about how machine registers are saved/restored in a call frame.  Are you asking how LLVM decides when to generate a CFI instruction?  Or are you wondering how CFI instructions turn into a .debug_frame section?
In either case, asking a more specific question on llvm-dev would get you a more informed answer.

From: cfe-dev [mailto:cfe-dev-bounces at lists.llvm.org<mailto:cfe-dev-bounces at lists.llvm.org>] On Behalf Of Siddharth Shankar Swain via cfe-dev
Sent: Monday, September 25, 2017 12:19 AM
To: Clang Dev
Subject: [cfe-dev] Call frame information query

Can anyone suggest how the CFI instructions are used to provide necessary information to the debugger ( lldb ) through the respective dwarf  entries  for CFI? It will be better if someone can point out to the implementation details .

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