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Revert "Work around invalid DWARF bugs for fat LTO" #95685

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Jul 16, 2022
Merged

Revert "Work around invalid DWARF bugs for fat LTO" #95685

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98190b7
Revert "Work around invalid DWARF bugs for fat LTO"
cbiffle Apr 4, 2022
42af197
Improve debuginfo test coverage for simple statics.
cbiffle Apr 5, 2022
2085d6a
Set minimum GDB version needed for basic-types-globals* tests.
luqmana Jul 15, 2022
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18 changes: 2 additions & 16 deletions compiler/rustc_codegen_llvm/src/back/lto.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -325,20 +325,6 @@ fn fat_lto(
drop(linker);
save_temp_bitcode(cgcx, &module, "lto.input");

// Fat LTO also suffers from the invalid DWARF issue similar to Thin LTO.
// Here we rewrite all `DICompileUnit` pointers if there is only one `DICompileUnit`.
// This only works around the problem when codegen-units = 1.
// Refer to the comments in the `optimize_thin_module` function for more details.
let mut cu1 = ptr::null_mut();
let mut cu2 = ptr::null_mut();
unsafe { llvm::LLVMRustLTOGetDICompileUnit(llmod, &mut cu1, &mut cu2) };
if !cu2.is_null() {
let _timer =
cgcx.prof.generic_activity_with_arg("LLVM_fat_lto_patch_debuginfo", &*module.name);
unsafe { llvm::LLVMRustLTOPatchDICompileUnit(llmod, cu1) };
save_temp_bitcode(cgcx, &module, "fat-lto-after-patch");
}

// Internalize everything below threshold to help strip out more modules and such.
unsafe {
let ptr = symbols_below_threshold.as_ptr();
Expand Down Expand Up @@ -757,7 +743,7 @@ pub unsafe fn optimize_thin_module(
// an error.
let mut cu1 = ptr::null_mut();
let mut cu2 = ptr::null_mut();
llvm::LLVMRustLTOGetDICompileUnit(llmod, &mut cu1, &mut cu2);
llvm::LLVMRustThinLTOGetDICompileUnit(llmod, &mut cu1, &mut cu2);
if !cu2.is_null() {
let msg = "multiple source DICompileUnits found";
return Err(write::llvm_err(&diag_handler, msg));
Expand Down Expand Up @@ -846,7 +832,7 @@ pub unsafe fn optimize_thin_module(
let _timer = cgcx
.prof
.generic_activity_with_arg("LLVM_thin_lto_patch_debuginfo", thin_module.name());
llvm::LLVMRustLTOPatchDICompileUnit(llmod, cu1);
llvm::LLVMRustThinLTOPatchDICompileUnit(llmod, cu1);
save_temp_bitcode(cgcx, &module, "thin-lto-after-patch");
}

Expand Down
8 changes: 6 additions & 2 deletions compiler/rustc_codegen_llvm/src/llvm/ffi.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2506,8 +2506,12 @@ extern "C" {
len: usize,
out_len: &mut usize,
) -> *const u8;
pub fn LLVMRustLTOGetDICompileUnit(M: &Module, CU1: &mut *mut c_void, CU2: &mut *mut c_void);
pub fn LLVMRustLTOPatchDICompileUnit(M: &Module, CU: *mut c_void);
pub fn LLVMRustThinLTOGetDICompileUnit(
M: &Module,
CU1: &mut *mut c_void,
CU2: &mut *mut c_void,
);
pub fn LLVMRustThinLTOPatchDICompileUnit(M: &Module, CU: *mut c_void);

pub fn LLVMRustLinkerNew(M: &Module) -> &mut Linker<'_>;
pub fn LLVMRustLinkerAdd(
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1611,7 +1611,7 @@ LLVMRustGetBitcodeSliceFromObjectData(const char *data,
// Rewrite all `DICompileUnit` pointers to the `DICompileUnit` specified. See
// the comment in `back/lto.rs` for why this exists.
extern "C" void
LLVMRustLTOGetDICompileUnit(LLVMModuleRef Mod,
LLVMRustThinLTOGetDICompileUnit(LLVMModuleRef Mod,
DICompileUnit **A,
DICompileUnit **B) {
Module *M = unwrap(Mod);
Expand All @@ -1629,7 +1629,7 @@ LLVMRustLTOGetDICompileUnit(LLVMModuleRef Mod,
// Rewrite all `DICompileUnit` pointers to the `DICompileUnit` specified. See
// the comment in `back/lto.rs` for why this exists.
extern "C" void
LLVMRustLTOPatchDICompileUnit(LLVMModuleRef Mod, DICompileUnit *Unit) {
LLVMRustThinLTOPatchDICompileUnit(LLVMModuleRef Mod, DICompileUnit *Unit) {
Module *M = unwrap(Mod);

// If the original source module didn't have a `DICompileUnit` then try to
Expand Down
81 changes: 81 additions & 0 deletions src/test/debuginfo/basic-types-globals-lto.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,81 @@
// Caveat - gdb doesn't know about UTF-32 character encoding and will print a
// rust char as only its numerical value.

// min-lldb-version: 310
// min-gdb-version: 8.0

// no-prefer-dynamic
// compile-flags:-g -C lto
// gdb-command:run
// gdbg-command:print 'basic_types_globals::B'
// gdbr-command:print B
// gdb-check:$1 = false
// gdbg-command:print 'basic_types_globals::I'
// gdbr-command:print I
// gdb-check:$2 = -1
// gdbg-command:print 'basic_types_globals::C'
// gdbr-command:print C
// gdbg-check:$3 = 97
// gdbr-check:$3 = 97
// gdbg-command:print/d 'basic_types_globals::I8'
// gdbr-command:print I8
// gdb-check:$4 = 68
// gdbg-command:print 'basic_types_globals::I16'
// gdbr-command:print I16
// gdb-check:$5 = -16
// gdbg-command:print 'basic_types_globals::I32'
// gdbr-command:print I32
// gdb-check:$6 = -32
// gdbg-command:print 'basic_types_globals::I64'
// gdbr-command:print I64
// gdb-check:$7 = -64
// gdbg-command:print 'basic_types_globals::U'
// gdbr-command:print U
// gdb-check:$8 = 1
// gdbg-command:print/d 'basic_types_globals::U8'
// gdbr-command:print U8
// gdb-check:$9 = 100
// gdbg-command:print 'basic_types_globals::U16'
// gdbr-command:print U16
// gdb-check:$10 = 16
// gdbg-command:print 'basic_types_globals::U32'
// gdbr-command:print U32
// gdb-check:$11 = 32
// gdbg-command:print 'basic_types_globals::U64'
// gdbr-command:print U64
// gdb-check:$12 = 64
// gdbg-command:print 'basic_types_globals::F32'
// gdbr-command:print F32
// gdb-check:$13 = 2.5
// gdbg-command:print 'basic_types_globals::F64'
// gdbr-command:print F64
// gdb-check:$14 = 3.5
// gdb-command:continue

#![allow(unused_variables)]
#![feature(omit_gdb_pretty_printer_section)]
#![omit_gdb_pretty_printer_section]

// N.B. These are `mut` only so they don't constant fold away.
static mut B: bool = false;
static mut I: isize = -1;
static mut C: char = 'a';
static mut I8: i8 = 68;
static mut I16: i16 = -16;
static mut I32: i32 = -32;
static mut I64: i64 = -64;
static mut U: usize = 1;
static mut U8: u8 = 100;
static mut U16: u16 = 16;
static mut U32: u32 = 32;
static mut U64: u64 = 64;
static mut F32: f32 = 2.5;
static mut F64: f64 = 3.5;

fn main() {
_zzz(); // #break

let a = unsafe { (B, I, C, I8, I16, I32, I64, U, U8, U16, U32, U64, F32, F64) };
}

fn _zzz() {()}
11 changes: 4 additions & 7 deletions src/test/debuginfo/basic-types-globals.rs
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Original file line number Diff line number Diff line change
@@ -1,11 +1,8 @@
// Caveats - gdb prints any 8-bit value (meaning rust I8 and u8 values)
// as its numerical value along with its associated ASCII char, there
// doesn't seem to be any way around this. Also, gdb doesn't know
// about UTF-32 character encoding and will print a rust char as only
// its numerical value.
// Caveat - gdb doesn't know about UTF-32 character encoding and will print a
// rust char as only its numerical value.

// min-lldb-version: 310
// ignore-gdb // Test temporarily ignored due to debuginfo tests being disabled, see PR 47155
// min-gdb-version: 8.0

// compile-flags:-g
// gdb-command:run
Expand All @@ -18,7 +15,7 @@
// gdbg-command:print 'basic_types_globals::C'
// gdbr-command:print C
// gdbg-check:$3 = 97
// gdbr-check:$3 = 97 'a'
// gdbr-check:$3 = 97
// gdbg-command:print/d 'basic_types_globals::I8'
// gdbr-command:print I8
// gdb-check:$4 = 68
Expand Down