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Hi Yonghae,</div>
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Could you provide a short example for this? Perhaps using <a href="https://godbolt.org/" id="LPNoLP561218">
https://godbolt.org/</a><br>
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(there is now a "ARM 64-BIT CLANG" compilers section)</div>
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I see some details about the frame pointer in:</div>
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llvm-project/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp<br>
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Though I haven't read it properly yet, it seems like it's not a simple case of not using it at all. It depends on circumstance.</div>
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Thanks,</div>
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David Spickett.<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> llvm-dev <llvm-dev-bounces@lists.llvm.org> on behalf of Yonghae Kim via llvm-dev <llvm-dev@lists.llvm.org><br>
<b>Sent:</b> 27 February 2020 01:27<br>
<b>To:</b> llvm-dev@lists.llvm.org <llvm-dev@lists.llvm.org><br>
<b>Subject:</b> [llvm-dev] LLVM AArch64 backend using stack pointer to reference local variables</font>
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<div class="PlainText">Hi all,<br>
<br>
I am wondering whether there is any way<br>
(i.e., compile option or different version of backend code that can be referred to)<br>
to make the LLVM AArch64 backend use the frame pointer instead of the stack pointer<br>
when it references (or locates) local variables in a stack frame.<br>
<br>
When I generate assembly code using LLVM AArch64 backend,<br>
it seems to use a stack pointer to locate the local variables in a stack frame.<br>
<br>
For example,<br>
....<br>
str wzr, [sp, #12] // e.g., local variable a<br>
str w8, [sp, #8] // e.g., local variable b<br>
str w9, [sp, #4] // e.g., local variable c<br>
str w10, [sp]<br>
…<br>
<br>
(It calculates offsets from a stack pointer and accesses the local variable using the stack pointer and the offsets.)<br>
<br>
The weird thing is all the other compiler tools are using a frame pointer rather than a stack pointer.<br>
I tried out "gcc", "clang", "LLVM x86 backend" and they are all referencing local variables using a frame pointer and its offsets.<br>
<br>
Is there any reasons that the only LLVM AArch64 uses a stack pointer?<br>
And, is there any way to make it use a frame pinter?<br>
<br>
I'd really appreciate for any comment or answer! :)<br>
<br>
Regards,<br>
Yonghae<br>
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