[ARM64] Debugging Arm64 debug binary gives memory access error when accessing local variables #40394

llvmbot · 2019-03-12T22:36:43Z


Bugzilla Link	41049
Resolution	FIXED
Resolved on	Oct 16, 2019 18:23
Version	unspecified
OS	Windows NT
Reporter	LLVM Bugzilla Contributor
CC	@dblohm7,@DougGregor,@jmorse,@zygoloid

Extended Description

Here are my repro steps. I believe this holds for any amd64 debug program.

int main() {
int x = 1;
}

Build the exe with clang-cl.exe --target=arm64-windows /Zi /Od test.cpp
Deploy test.exe / test.pdb to arm64 machine
Open exe under debugger, and break into code (windbg.exe test.exe, then bp test!main in command line)
step into function and try to observe value of local variable.
expected: local variable value displays
actual: memory access error reported

No repro on amd64.
With arm64 retail (/O2 instead of /Od), no issue except for volatile variables, which also have memory access error.

llvmbot · 2019-05-06T21:55:04Z

We're seeing this in Firefox Nightly builds as well. Unlike comment 0, we use /O2 but still have problems with locals.

Here's a real-world build if it helps, although starting with the simpler reproducer from the original report may be a better idea:

Results:

Locals not available, and this message often appears in the debug output:
CvRegToMachine(arm64) conversion failure for 0x1

llvmbot · 2019-06-03T22:30:15Z

This should be resolved by rL362280 (https://reviews.llvm.org/rL362280)

llvmbot · 2019-06-03T22:37:01Z

That's great, thanks for the pointer! I'll try to confirm this the next time I build for arm (which isn't too often anymore).

llvmbot transferred this issue from llvm/llvm-bugzilla-archive Dec 10, 2021

This issue was closed.