codegen_ssa: no dbginfo for scalable vec local w/ -O0

compiler/rustc_codegen_ssa/src/mir/debuginfo.rs

@@ -10,7 +10,7 @@ use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
 use rustc_middle::ty::{Instance, Ty};
 use rustc_middle::{bug, mir, ty};
-use rustc_session::config::DebugInfo;
+use rustc_session::config::{DebugInfo, OptLevel};
 use rustc_span::{BytePos, DUMMY_SP, Span, Symbol, hygiene, sym};
 
 use super::operand::{OperandRef, OperandValue};
@@ -456,6 +456,18 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             LocalRef::UnsizedPlace(_) => return,
         };
 
+        // FIXME(arm-maintainers): LLVM uses GlobalISel with -O0 that doesn't support scalable
+        // vectors. It normally falls back to SDAG which does support scalable vectors, but there's
+        // a bug that means that isn't happening for debuginfo - so temporarily don't emit debuginfo
+        // for scalable vector locals when there are no optimisations until that bug is
+        // fixed. See <https://github.com/llvm/llvm-project/issues/204585>.
+        if base.layout.peel_transparent_wrappers(bx).ty.is_scalable_vector()
+            && bx.tcx().backend_optimization_level(()) == OptLevel::No
+            && bx.sess().opts.debuginfo != DebugInfo::None
+        {
+            return;
+        }
+
         let vars = vars.iter().cloned().chain(fallback_var);
 
         for var in vars {

tests/ui/scalable-vectors/debuginfo-no-opt-llvm-ice.rs

@@ -0,0 +1,40 @@
+//@ only-aarch64
+//@ build-pass
+//@ compile-flags: -Ctarget-feature=+sve,+sve2 -Copt-level=0 -g
+//@ edition:2021
+#![feature(stdarch_aarch64_sve)]
+
+use std::arch::aarch64::*;
+
+static I8_275: [i8; 275] = [
+    0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf, 0x10, 0x11,
+    0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21,
+    0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31,
+    0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41,
+    0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51,
+    0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60, 0x61,
+    0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71,
+    0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, -0x80,
+    -0x7f, -0x7e, -0x7d, -0x7c, -0x7b, -0x7a, -0x79, -0x78, -0x77, -0x76, -0x75, -0x74, -0x73,
+    -0x72, -0x71, -0x70, -0x6f, -0x6e, -0x6d, -0x6c, -0x6b, -0x6a, -0x69, -0x68, -0x67, -0x66,
+    -0x65, -0x64, -0x63, -0x62, -0x61, -0x60, -0x5f, -0x5e, -0x5d, -0x5c, -0x5b, -0x5a, -0x59,
+    -0x58, -0x57, -0x56, -0x55, -0x54, -0x53, -0x52, -0x51, -0x50, -0x4f, -0x4e, -0x4d, -0x4c,
+    -0x4b, -0x4a, -0x49, -0x48, -0x47, -0x46, -0x45, -0x44, -0x43, -0x42, -0x41, -0x40, -0x3f,
+    -0x3e, -0x3d, -0x3c, -0x3b, -0x3a, -0x39, -0x38, -0x37, -0x36, -0x35, -0x34, -0x33, -0x32,
+    -0x31, -0x30, -0x2f, -0x2e, -0x2d, -0x2c, -0x2b, -0x2a, -0x29, -0x28, -0x27, -0x26, -0x25,
+    -0x24, -0x23, -0x22, -0x21, -0x20, -0x1f, -0x1e, -0x1d, -0x1c, -0x1b, -0x1a, -0x19, -0x18,
+    -0x17, -0x16, -0x15, -0x14, -0x13, -0x12, -0x11, -0x10, -0xf, -0xe, -0xd, -0xc, -0xb, -0xa,
+    -0x9, -0x8, -0x7, -0x6, -0x5, -0x4, -0x3, -0x2, -0x1, 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7,
+    0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf, 0x10, 0x11, 0x12,
+];
+
+fn main() {
+    unsafe {
+        let __pred = svptrue_b8();
+        let op1_val = svld1_s8(__pred, I8_275.as_ptr().add(0) as _);
+
+        let mut __c_return_value = std::mem::MaybeUninit::uninit();
+        std::ptr::write(__c_return_value.as_mut_ptr(), svext_s8::<0>(op1_val, op1_val));
+        let __c_return_value = __c_return_value.assume_init();
+    }
+}