https://github.com/dlav-sc created https://github.com/llvm/llvm-project/pull/164813
This patch makes DWARF fission compatible with RISC-V relaxations by using indirect addressing for the DW_AT_high_pc attribute. This eliminates the remaining relocations in .dwo files. >From f14d5e7295fa75ee6658828e0806e2ed994e0e3c Mon Sep 17 00:00:00 2001 From: Daniil Avdeev <[email protected]> Date: Thu, 18 Sep 2025 02:05:39 +0000 Subject: [PATCH] [dwarf] make dwarf fission compatible with RISCV relaxations 2/2 This patch makes DWARF fission compatible with RISC-V relaxations by using indirect addressing for the DW_AT_high_pc attribute. This eliminates the remaining relocations in .dwo files. --- .../CodeGen/AsmPrinter/DwarfCompileUnit.cpp | 8 ++-- llvm/test/DebugInfo/RISCV/relax_dwo_ranges.ll | 44 +++++++++++++------ 2 files changed, 35 insertions(+), 17 deletions(-) diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp index 518121e200190..12ad5c18e9600 100644 --- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp +++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp @@ -493,10 +493,12 @@ void DwarfCompileUnit::attachLowHighPC(DIE &D, const MCSymbol *Begin, assert(End->isDefined() && "Invalid end label"); addLabelAddress(D, dwarf::DW_AT_low_pc, Begin); - if (DD->getDwarfVersion() < 4) - addLabelAddress(D, dwarf::DW_AT_high_pc, End); - else + if (DD->getDwarfVersion() >= 4 && + (!isDwoUnit() || !llvm::isRangeRelaxable(Begin, End))) { addLabelDelta(D, dwarf::DW_AT_high_pc, End, Begin); + return; + } + addLabelAddress(D, dwarf::DW_AT_high_pc, End); } // Add info for Wasm-global-based relocation. diff --git a/llvm/test/DebugInfo/RISCV/relax_dwo_ranges.ll b/llvm/test/DebugInfo/RISCV/relax_dwo_ranges.ll index f8ab7fc5ad900..64f83ba1a7d7f 100644 --- a/llvm/test/DebugInfo/RISCV/relax_dwo_ranges.ll +++ b/llvm/test/DebugInfo/RISCV/relax_dwo_ranges.ll @@ -1,12 +1,13 @@ ; RUN: llc -dwarf-version=5 -split-dwarf-file=foo.dwo -O0 %s -mtriple=riscv64-unknown-linux-gnu -filetype=obj -o %t ; RUN: llvm-dwarfdump -v %t | FileCheck --check-prefix=DWARF5 %s ; RUN: llvm-dwarfdump --debug-info %t 2> %t.txt -; RUN: FileCheck --input-file=%t.txt %s --check-prefix=RELOCS --implicit-check-not=warning: +; RUN: FileCheck --input-file=%t.txt %s --check-prefix=RELOCS --allow-empty --implicit-check-not=warning: ; RUN: llc -dwarf-version=4 -split-dwarf-file=foo.dwo -O0 %s -mtriple=riscv64-unknown-linux-gnu -filetype=obj -o %t ; RUN: llvm-dwarfdump -v %t | FileCheck --check-prefix=DWARF4 %s ; RUN: llvm-dwarfdump --debug-info %t 2> %t.txt -; RUN: FileCheck --input-file=%t.txt %s --check-prefix=RELOCS --implicit-check-not=warning: +; RUN: FileCheck --input-file=%t.txt %s --check-prefix=RELOCS --allow-empty --implicit-check-not=warning: +; RUN: llvm-objdump -h %t | FileCheck --check-prefix=HDR %s ; In the RISC-V architecture, the .text section is subject to ; relaxation, meaning the start address of each function can change @@ -49,60 +50,75 @@ ; clang -g -S -gsplit-dwarf --target=riscv64 -march=rv64gc -O0 relax_dwo_ranges.cpp -; Currently, square() still uses an offset to represent the function's end address, -; which requires a relocation here. -; RELOCS: warning: unexpected relocations for dwo section '.debug_info.dwo' +; RELOCS-NOT: warning: unexpected relocations for dwo section '.debug_info.dwo' +; Make sure we don't produce any relocations in any .dwo section +; HDR-NOT: .rela.{{.*}}.dwo + +; Ensure that 'square()' function uses indexed start and end addresses ; DWARF5: .debug_info.dwo contents: ; DWARF5: DW_TAG_subprogram -; DWARF5-NEXT: DW_AT_low_pc [DW_FORM_addrx] (indexed (00000000) address = 0x0000000000000000 ".text") -; DWARF5-NEXT: DW_AT_high_pc [DW_FORM_data4] (0x00000000) +; DWARF5-NEXT: DW_AT_low_pc [DW_FORM_addrx] (indexed (00000000) address = 0x0000000000000000 ".text") +; DWARF5-NEXT: DW_AT_high_pc [DW_FORM_addrx] (indexed (00000001) address = 0x0000000000000044 ".text") ; DWARF5: DW_AT_name {{.*}} "square") ; DWARF5: DW_TAG_formal_parameter +; HDR-NOT: .rela.{{.*}}.dwo + ; Ensure there is no unnecessary addresses in .o file ; DWARF5: .debug_addr contents: ; DWARF5: Addrs: [ ; DWARF5-NEXT: 0x0000000000000000 +; DWARF5-NEXT: 0x0000000000000044 ; DWARF5-NEXT: 0x0000000000000046 ; DWARF5-NEXT: 0x000000000000006c ; DWARF5-NEXT: 0x00000000000000b0 ; DWARF5-NEXT: ] +; HDR-NOT: .rela.{{.*}}.dwo + ; Ensure that 'boo()' and 'main()' use DW_RLE_startx_length and DW_RLE_startx_endx ; entries respectively ; DWARF5: .debug_rnglists.dwo contents: ; DWARF5: ranges: -; DWARF5-NEXT: 0x00000014: [DW_RLE_startx_length]: 0x0000000000000001, 0x0000000000000024 => [0x0000000000000046, 0x000000000000006a) +; DWARF5-NEXT: 0x00000014: [DW_RLE_startx_length]: 0x0000000000000002, 0x0000000000000024 => [0x0000000000000046, 0x000000000000006a) ; DWARF5-NEXT: 0x00000017: [DW_RLE_end_of_list ] -; DWARF5-NEXT: 0x00000018: [DW_RLE_startx_endx ]: 0x0000000000000002, 0x0000000000000003 => [0x000000000000006c, 0x00000000000000b0) +; DWARF5-NEXT: 0x00000018: [DW_RLE_startx_endx ]: 0x0000000000000003, 0x0000000000000004 => [0x000000000000006c, 0x00000000000000b0) ; DWARF5-NEXT: 0x0000001b: [DW_RLE_end_of_list ] ; DWARF5-EMPTY: +; HDR-NOT: .rela.{{.*}}.dwo + ; DWARF4: .debug_info.dwo contents: ; DWARF4: DW_TAG_subprogram -; DWARF4-NEXT: DW_AT_low_pc [DW_FORM_GNU_addr_index] (indexed (00000000) address = 0x0000000000000000 ".text") -; DWARF4-NEXT: DW_AT_high_pc [DW_FORM_data4] (0x00000000) +; DWARF4-NEXT: DW_AT_low_pc [DW_FORM_GNU_addr_index] (indexed (00000000) address = 0x0000000000000000 ".text") +; DWARF4-NEXT: DW_AT_high_pc [DW_FORM_GNU_addr_index] (indexed (00000001) address = 0x0000000000000044 ".text") ; DWARF4: DW_AT_name {{.*}} "square") ; DWARF4: DW_TAG_subprogram -; DWARF4-NEXT: DW_AT_low_pc [DW_FORM_GNU_addr_index] (indexed (00000001) address = 0x0000000000000046 ".text") +; DWARF4-NEXT: DW_AT_low_pc [DW_FORM_GNU_addr_index] (indexed (00000002) address = 0x0000000000000046 ".text") ; DWARF4-NEXT: DW_AT_high_pc [DW_FORM_data4] (0x00000024) ; DWARF4: DW_AT_name {{.*}} "boo") ; DWARF4: DW_TAG_subprogram -; DWARF4-NEXT: DW_AT_low_pc [DW_FORM_GNU_addr_index] (indexed (00000002) address = 0x000000000000006c ".text") -; DWARF4-NEXT: DW_AT_high_pc [DW_FORM_data4] (0x00000000) +; DWARF4-NEXT: DW_AT_low_pc [DW_FORM_GNU_addr_index] (indexed (00000003) address = 0x000000000000006c ".text") +; DWARF4-NEXT: DW_AT_high_pc [DW_FORM_GNU_addr_index] (indexed (00000004) address = 0x00000000000000b0 ".text") ; DWARF4: DW_AT_name {{.*}} "main") +; HDR-NOT: .rela.{{.*}}.dwo + ; Ensure there is no unnecessary addresses in .o file ; DWARF4: .debug_addr contents: ; DWARF4: Addrs: [ ; DWARF4-NEXT: 0x0000000000000000 +; DWARF4-NEXT: 0x0000000000000044 ; DWARF4-NEXT: 0x0000000000000046 ; DWARF4-NEXT: 0x000000000000006c +; DWARF4-NEXT: 0x00000000000000b0 ; DWARF4-NEXT: ] +; HDR-NOT: .rela.{{.*}}.dwo + ; Function Attrs: mustprogress noinline optnone define dso_local noundef signext i32 @_Z6squarei(i32 noundef signext %0) #0 !dbg !11 { %2 = alloca i32, align 4 _______________________________________________ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
