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Do not produce fragment for ZST.

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This commit is contained in:
Camille GILLOT 2023-08-26 15:40:29 +00:00
parent f49494ecce
commit 930b2e72ee
3 changed files with 49 additions and 15 deletions
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19
compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
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@ -584,17 +584,22 @@ pub fn compute_per_local_var_debug_info(
}
let place = fragment.contents;
let fragment = if fragment_layout.size == Size::ZERO {
// Fragment is a ZST, so does not represent anything.
continue;
} else if fragment_layout.size == var_layout.size {
// Fragment covers entire variable, so as far as
// DWARF is concerned, it's not really a fragment.
None
} else {
Some(fragment_start..fragment_start + fragment_layout.size)
};
per_local[place.local].push(PerLocalVarDebugInfo {
name: var.name,
source_info: var.source_info,
dbg_var,
fragment: if fragment_layout.size == var_layout.size {
// Fragment covers entire variable, so as far as
// DWARF is concerned, it's not really a fragment.
None
} else {
Some(fragment_start..fragment_start + fragment_layout.size)
},
fragment,
projection: place.projection,
});
}

14
tests/codegen/sroa-fragment-debuginfo.rs
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@ -29,17 +29,15 @@ pub struct ZstSlice<'input> {
#[no_mangle]
pub fn zst(s: &[u8]) {
// The field `extra` is a ZST. The fragment for the field `slice` encompasses the whole
// variable, so is not a fragment. In that case, the variable must have no fragment.
// CHECK: void @zst(
// CHECK: %slice.dbg.spill1 = alloca { ptr, i64 },
// CHECK: %slice.dbg.spill = alloca %Zst,
// CHECK: %s.dbg.spill = alloca { ptr, i64 },
// CHECK: call void @llvm.dbg.declare(metadata ptr %s.dbg.spill, metadata ![[S_ZST:.*]], metadata !DIExpression()),
// CHECK: call void @llvm.dbg.declare(metadata ptr %slice.dbg.spill, metadata ![[SLICE_ZST:.*]], metadata !DIExpression(DW_OP_LLVM_fragment, 0, 0)),
// CHECK: call void @llvm.dbg.declare(metadata ptr %slice.dbg.spill1, metadata ![[SLICE_ZST]], metadata !DIExpression()),
// CHECK-NOT: call void @llvm.dbg.declare(metadata ptr %slice.dbg.spill, metadata !{}, metadata !DIExpression(DW_OP_LLVM_fragment,
// CHECK: call void @llvm.dbg.declare(metadata ptr %{{.*}}, metadata ![[SLICE_ZST:.*]], metadata !DIExpression()),
// CHECK-NOT: call void @llvm.dbg.declare(metadata ptr %{{.*}}, metadata ![[SLICE_ZST]],
let slice = ZstSlice { slice: s, extra: Zst };
}
// CHECK: ![[S_EXTRA]] = !DILocalVariable(name: "s",
// CHECK: ![[SLICE_EXTRA]] = !DILocalVariable(name: "slice",
// CHECK: ![[S_ZST]] = !DILocalVariable(name: "s",
// CHECK: ![[SLICE_ZST]] = !DILocalVariable(name: "slice",

31
tests/ui/debuginfo/sroa-fragment-debuginfo.rs Normal file
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@ -0,0 +1,31 @@
// Verify that we do not trigger a LLVM assertion by creating zero-sized DWARF fragments.
//
// build-pass
// compile-flags: -g -Zmir-opt-level=0 -Zmir-enable-passes=+ScalarReplacementOfAggregates
// compile-flags: -Cno-prepopulate-passes
#![crate_type = "lib"]
pub struct ExtraSlice<'input> {
slice: &'input [u8],
extra: u32,
}
#[no_mangle]
pub fn extra(s: &[u8]) {
let slice = ExtraSlice { slice: s, extra: s.len() as u32 };
}
struct Zst;
pub struct ZstSlice<'input> {
slice: &'input [u8],
extra: Zst,
}
#[no_mangle]
pub fn zst(s: &[u8]) {
// The field `extra` is a ZST. The fragment for the field `slice` encompasses the whole
// variable, so is not a fragment. In that case, the variable must have no fragment.
let slice = ZstSlice { slice: s, extra: Zst };
}