/* Original C (for context): * __attribute__((noinline)) * int loop_reg_rotate(int n, int seed) { * volatile int acc = seed; // keep as a named local * int i = 0, j = 1, k = 2; // extra pressure but not enough to spill * * for (int t = 0; t < n; ++t) { * // Mix uses so the allocator may reshuffle regs for 'acc' * acc = acc + i; * asm volatile("" :: "r"(acc)); // pin 'acc' live here * acc = acc ^ j; * asm volatile("" :: "r"(acc)); // and here * acc = acc + k; * i ^= acc; j += acc; k ^= j; * } * * asm volatile("" :: "r"(acc)); * return acc + i + j + k; * } */ .file "loop_reg_rotate.c" .text .globl loop_reg_rotate # -- Begin function loop_reg_rotate .p2align 4 .type loop_reg_rotate,@function loop_reg_rotate: # @loop_reg_rotate .Lfunc_begin0: .file 0 "." "loop_reg_rotate.c" md5 0x388f52de76e9442230e689fb9be1b4ef .loc 0 2 0 # loop_reg_rotate.c:2:0 .cfi_startproc # %bb.0: # %entry #DEBUG_VALUE: loop_reg_rotate:n <- $edi #DEBUG_VALUE: loop_reg_rotate:seed <- $esi pushq %rbp .cfi_def_cfa_offset 16 .cfi_offset %rbp, -16 movq %rsp, %rbp .cfi_def_cfa_register %rbp .Ltmp0: .loc 0 3 16 prologue_end # loop_reg_rotate.c:3:16 movl %esi, -4(%rbp) .Ltmp1: #DEBUG_VALUE: loop_reg_rotate:i <- 0 #DEBUG_VALUE: loop_reg_rotate:j <- 1 #DEBUG_VALUE: loop_reg_rotate:k <- 2 #DEBUG_VALUE: t <- 0 .loc 0 6 21 # loop_reg_rotate.c:6:21 testl %edi, %edi .Ltmp2: .loc 0 6 3 is_stmt 0 # loop_reg_rotate.c:6:3 jle .LBB0_1 .Ltmp3: # %bb.3: # %for.body.preheader #DEBUG_VALUE: loop_reg_rotate:n <- $edi #DEBUG_VALUE: loop_reg_rotate:seed <- $esi #DEBUG_VALUE: loop_reg_rotate:i <- 0 #DEBUG_VALUE: loop_reg_rotate:j <- 1 #DEBUG_VALUE: loop_reg_rotate:k <- 2 #DEBUG_VALUE: t <- 0 .loc 0 0 3 # loop_reg_rotate.c:0:3 xorl %eax, %eax movl $1, %edx movl $2, %ecx .Ltmp4: .p2align 4 .LBB0_4: # %for.body # =>This Inner Loop Header: Depth=1 #DEBUG_VALUE: loop_reg_rotate:n <- [DW_OP_LLVM_entry_value 1] $edi #DEBUG_VALUE: loop_reg_rotate:seed <- [DW_OP_LLVM_entry_value 1] $esi #DEBUG_VALUE: t <- [DW_OP_LLVM_arg 0, DW_OP_LLVM_arg 1, DW_OP_minus, DW_OP_consts 18446744073709551615, DW_OP_div, DW_OP_stack_value] undef, undef #DEBUG_VALUE: loop_reg_rotate:k <- $ecx #DEBUG_VALUE: loop_reg_rotate:j <- $edx #DEBUG_VALUE: loop_reg_rotate:i <- $eax .loc 0 8 9 is_stmt 1 # loop_reg_rotate.c:8:9 addl %eax, -4(%rbp) .loc 0 9 28 # loop_reg_rotate.c:9:28 movl -4(%rbp), %esi .loc 0 9 5 is_stmt 0 # loop_reg_rotate.c:9:5 #APP #NO_APP .loc 0 10 9 is_stmt 1 # loop_reg_rotate.c:10:9 xorl %edx, -4(%rbp) .loc 0 11 28 # loop_reg_rotate.c:11:28 movl -4(%rbp), %esi .loc 0 11 5 is_stmt 0 # loop_reg_rotate.c:11:5 #APP #NO_APP .loc 0 12 9 is_stmt 1 # loop_reg_rotate.c:12:9 addl %ecx, -4(%rbp) .loc 0 13 7 # loop_reg_rotate.c:13:7 xorl -4(%rbp), %eax .Ltmp5: #DEBUG_VALUE: loop_reg_rotate:i <- $eax .loc 0 13 17 is_stmt 0 # loop_reg_rotate.c:13:17 addl -4(%rbp), %edx .Ltmp6: #DEBUG_VALUE: loop_reg_rotate:j <- $edx .loc 0 13 27 # loop_reg_rotate.c:13:27 xorl %edx, %ecx .Ltmp7: #DEBUG_VALUE: loop_reg_rotate:k <- $ecx #DEBUG_VALUE: t <- [DW_OP_LLVM_arg 0, DW_OP_LLVM_arg 1, DW_OP_minus, DW_OP_consts 18446744073709551615, DW_OP_div, DW_OP_consts 1, DW_OP_plus, DW_OP_stack_value] undef, undef .loc 0 6 21 is_stmt 1 # loop_reg_rotate.c:6:21 decl %edi .Ltmp8: .loc 0 6 3 is_stmt 0 # loop_reg_rotate.c:6:3 jne .LBB0_4 jmp .LBB0_2 .Ltmp9: .LBB0_1: #DEBUG_VALUE: loop_reg_rotate:n <- $edi #DEBUG_VALUE: loop_reg_rotate:seed <- $esi #DEBUG_VALUE: loop_reg_rotate:i <- 0 #DEBUG_VALUE: loop_reg_rotate:j <- 1 #DEBUG_VALUE: loop_reg_rotate:k <- 2 #DEBUG_VALUE: t <- 0 .loc 0 0 3 # loop_reg_rotate.c:0:3 movl $2, %ecx movl $1, %edx xorl %eax, %eax .Ltmp10: .LBB0_2: # %for.cond.cleanup #DEBUG_VALUE: loop_reg_rotate:n <- [DW_OP_LLVM_entry_value 1] $edi #DEBUG_VALUE: loop_reg_rotate:seed <- [DW_OP_LLVM_entry_value 1] $esi .loc 0 16 26 is_stmt 1 # loop_reg_rotate.c:16:26 movl -4(%rbp), %esi .loc 0 16 3 is_stmt 0 # loop_reg_rotate.c:16:3 #APP #NO_APP .loc 0 17 14 is_stmt 1 # loop_reg_rotate.c:17:14 addl %edx, %eax .loc 0 17 18 is_stmt 0 # loop_reg_rotate.c:17:18 addl %ecx, %eax .loc 0 17 22 # loop_reg_rotate.c:17:22 addl -4(%rbp), %eax .loc 0 17 3 epilogue_begin # loop_reg_rotate.c:17:3 popq %rbp .cfi_def_cfa %rsp, 8 retq .Ltmp11: .Lfunc_end0: .size loop_reg_rotate, .Lfunc_end0-loop_reg_rotate .cfi_endproc # -- End function .section .debug_loclists,"",@progbits .long .Ldebug_list_header_end0-.Ldebug_list_header_start0 # Length .Ldebug_list_header_start0: .short 5 # Version .byte 8 # Address size .byte 0 # Segment selector size .long 6 # Offset entry count .Lloclists_table_base0: .long .Ldebug_loc0-.Lloclists_table_base0 .long .Ldebug_loc1-.Lloclists_table_base0 .long .Ldebug_loc2-.Lloclists_table_base0 .long .Ldebug_loc3-.Lloclists_table_base0 .long .Ldebug_loc4-.Lloclists_table_base0 .long .Ldebug_loc5-.Lloclists_table_base0 .Ldebug_loc0: .byte 4 # DW_LLE_offset_pair .uleb128 .Lfunc_begin0-.Lfunc_begin0 # starting offset .uleb128 .Ltmp4-.Lfunc_begin0 # ending offset .byte 1 # Loc expr size .byte 85 # super-register DW_OP_reg5 .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp4-.Lfunc_begin0 # starting offset .uleb128 .Ltmp9-.Lfunc_begin0 # ending offset .byte 4 # Loc expr size .byte 163 # DW_OP_entry_value .byte 1 # 1 .byte 85 # super-register DW_OP_reg5 .byte 159 # DW_OP_stack_value .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp9-.Lfunc_begin0 # starting offset .uleb128 .Ltmp10-.Lfunc_begin0 # ending offset .byte 1 # Loc expr size .byte 85 # super-register DW_OP_reg5 .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp10-.Lfunc_begin0 # starting offset .uleb128 .Lfunc_end0-.Lfunc_begin0 # ending offset .byte 4 # Loc expr size .byte 163 # DW_OP_entry_value .byte 1 # 1 .byte 85 # super-register DW_OP_reg5 .byte 159 # DW_OP_stack_value .byte 0 # DW_LLE_end_of_list .Ldebug_loc1: .byte 4 # DW_LLE_offset_pair .uleb128 .Lfunc_begin0-.Lfunc_begin0 # starting offset .uleb128 .Ltmp4-.Lfunc_begin0 # ending offset .byte 1 # Loc expr size .byte 84 # super-register DW_OP_reg4 .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp4-.Lfunc_begin0 # starting offset .uleb128 .Ltmp9-.Lfunc_begin0 # ending offset .byte 4 # Loc expr size .byte 163 # DW_OP_entry_value .byte 1 # 1 .byte 84 # super-register DW_OP_reg4 .byte 159 # DW_OP_stack_value .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp9-.Lfunc_begin0 # starting offset .uleb128 .Ltmp10-.Lfunc_begin0 # ending offset .byte 1 # Loc expr size .byte 84 # super-register DW_OP_reg4 .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp10-.Lfunc_begin0 # starting offset .uleb128 .Lfunc_end0-.Lfunc_begin0 # ending offset .byte 4 # Loc expr size .byte 163 # DW_OP_entry_value .byte 1 # 1 .byte 84 # super-register DW_OP_reg4 .byte 159 # DW_OP_stack_value .byte 0 # DW_LLE_end_of_list .Ldebug_loc2: .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp1-.Lfunc_begin0 # starting offset .uleb128 .Ltmp4-.Lfunc_begin0 # ending offset .byte 3 # Loc expr size .byte 17 # DW_OP_consts .byte 0 # 0 .byte 159 # DW_OP_stack_value .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp4-.Lfunc_begin0 # starting offset .uleb128 .Ltmp9-.Lfunc_begin0 # ending offset .byte 1 # Loc expr size .byte 80 # super-register DW_OP_reg0 .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp9-.Lfunc_begin0 # starting offset .uleb128 .Ltmp10-.Lfunc_begin0 # ending offset .byte 3 # Loc expr size .byte 17 # DW_OP_consts .byte 0 # 0 .byte 159 # DW_OP_stack_value .byte 0 # DW_LLE_end_of_list .Ldebug_loc3: .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp1-.Lfunc_begin0 # starting offset .uleb128 .Ltmp4-.Lfunc_begin0 # ending offset .byte 3 # Loc expr size .byte 17 # DW_OP_consts .byte 1 # 1 .byte 159 # DW_OP_stack_value .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp4-.Lfunc_begin0 # starting offset .uleb128 .Ltmp9-.Lfunc_begin0 # ending offset .byte 1 # Loc expr size .byte 81 # super-register DW_OP_reg1 .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp9-.Lfunc_begin0 # starting offset .uleb128 .Ltmp10-.Lfunc_begin0 # ending offset .byte 3 # Loc expr size .byte 17 # DW_OP_consts .byte 1 # 1 .byte 159 # DW_OP_stack_value .byte 0 # DW_LLE_end_of_list .Ldebug_loc4: .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp1-.Lfunc_begin0 # starting offset .uleb128 .Ltmp4-.Lfunc_begin0 # ending offset .byte 3 # Loc expr size .byte 17 # DW_OP_consts .byte 2 # 2 .byte 159 # DW_OP_stack_value .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp4-.Lfunc_begin0 # starting offset .uleb128 .Ltmp9-.Lfunc_begin0 # ending offset .byte 1 # Loc expr size .byte 82 # super-register DW_OP_reg2 .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp9-.Lfunc_begin0 # starting offset .uleb128 .Ltmp10-.Lfunc_begin0 # ending offset .byte 3 # Loc expr size .byte 17 # DW_OP_consts .byte 2 # 2 .byte 159 # DW_OP_stack_value .byte 0 # DW_LLE_end_of_list .Ldebug_loc5: .byte 4 # DW_LLE_offset_pair .uleb128 .Ltmp1-.Lfunc_begin0 # starting offset .uleb128 .Ltmp4-.Lfunc_begin0 # ending offset .byte 3 # Loc expr size .byte 17 # DW_OP_consts .byte 0 # 0 .byte 159 # DW_OP_stack_value .byte 0 # DW_LLE_end_of_list .Ldebug_list_header_end0: .section .debug_abbrev,"",@progbits .byte 1 # Abbreviation Code .byte 17 # DW_TAG_compile_unit .byte 1 # DW_CHILDREN_yes .byte 37 # DW_AT_producer .byte 37 # DW_FORM_strx1 .byte 19 # DW_AT_language .byte 5 # DW_FORM_data2 .byte 3 # DW_AT_name .byte 37 # DW_FORM_strx1 .byte 114 # DW_AT_str_offsets_base .byte 23 # DW_FORM_sec_offset .byte 16 # DW_AT_stmt_list .byte 23 # DW_FORM_sec_offset .byte 27 # DW_AT_comp_dir .byte 37 # DW_FORM_strx1 .byte 17 # DW_AT_low_pc .byte 27 # DW_FORM_addrx .byte 18 # DW_AT_high_pc .byte 6 # DW_FORM_data4 .byte 115 # DW_AT_addr_base .byte 23 # DW_FORM_sec_offset .ascii "\214\001" # DW_AT_loclists_base .byte 23 # DW_FORM_sec_offset .byte 0 # EOM(1) .byte 0 # EOM(2) .byte 2 # Abbreviation Code .byte 46 # DW_TAG_subprogram .byte 1 # DW_CHILDREN_yes .byte 17 # DW_AT_low_pc .byte 27 # DW_FORM_addrx .byte 18 # DW_AT_high_pc .byte 6 # DW_FORM_data4 .byte 64 # DW_AT_frame_base .byte 24 # DW_FORM_exprloc .byte 122 # DW_AT_call_all_calls .byte 25 # DW_FORM_flag_present .byte 3 # DW_AT_name .byte 37 # DW_FORM_strx1 .byte 58 # DW_AT_decl_file .byte 11 # DW_FORM_data1 .byte 59 # DW_AT_decl_line .byte 11 # DW_FORM_data1 .byte 39 # DW_AT_prototyped .byte 25 # DW_FORM_flag_present .byte 73 # DW_AT_type .byte 19 # DW_FORM_ref4 .byte 63 # DW_AT_external .byte 25 # DW_FORM_flag_present .byte 0 # EOM(1) .byte 0 # EOM(2) .byte 3 # Abbreviation Code .byte 5 # DW_TAG_formal_parameter .byte 0 # DW_CHILDREN_no .byte 2 # DW_AT_location .byte 34 # DW_FORM_loclistx .byte 3 # DW_AT_name .byte 37 # DW_FORM_strx1 .byte 58 # DW_AT_decl_file .byte 11 # DW_FORM_data1 .byte 59 # DW_AT_decl_line .byte 11 # DW_FORM_data1 .byte 73 # DW_AT_type .byte 19 # DW_FORM_ref4 .byte 0 # EOM(1) .byte 0 # EOM(2) .byte 4 # Abbreviation Code .byte 52 # DW_TAG_variable .byte 0 # DW_CHILDREN_no .byte 2 # DW_AT_location .byte 24 # DW_FORM_exprloc .byte 3 # DW_AT_name .byte 37 # DW_FORM_strx1 .byte 58 # DW_AT_decl_file .byte 11 # DW_FORM_data1 .byte 59 # DW_AT_decl_line .byte 11 # DW_FORM_data1 .byte 73 # DW_AT_type .byte 19 # DW_FORM_ref4 .byte 0 # EOM(1) .byte 0 # EOM(2) .byte 5 # Abbreviation Code .byte 52 # DW_TAG_variable .byte 0 # DW_CHILDREN_no .byte 2 # DW_AT_location .byte 34 # DW_FORM_loclistx .byte 3 # DW_AT_name .byte 37 # DW_FORM_strx1 .byte 58 # DW_AT_decl_file .byte 11 # DW_FORM_data1 .byte 59 # DW_AT_decl_line .byte 11 # DW_FORM_data1 .byte 73 # DW_AT_type .byte 19 # DW_FORM_ref4 .byte 0 # EOM(1) .byte 0 # EOM(2) .byte 6 # Abbreviation Code .byte 11 # DW_TAG_lexical_block .byte 1 # DW_CHILDREN_yes .byte 17 # DW_AT_low_pc .byte 27 # DW_FORM_addrx .byte 18 # DW_AT_high_pc .byte 6 # DW_FORM_data4 .byte 0 # EOM(1) .byte 0 # EOM(2) .byte 7 # Abbreviation Code .byte 36 # DW_TAG_base_type .byte 0 # DW_CHILDREN_no .byte 3 # DW_AT_name .byte 37 # DW_FORM_strx1 .byte 62 # DW_AT_encoding .byte 11 # DW_FORM_data1 .byte 11 # DW_AT_byte_size .byte 11 # DW_FORM_data1 .byte 0 # EOM(1) .byte 0 # EOM(2) .byte 8 # Abbreviation Code .byte 53 # DW_TAG_volatile_type .byte 0 # DW_CHILDREN_no .byte 73 # DW_AT_type .byte 19 # DW_FORM_ref4 .byte 0 # EOM(1) .byte 0 # EOM(2) .byte 0 # EOM(3) .section .debug_info,"",@progbits .Lcu_begin0: .long .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit .Ldebug_info_start0: .short 5 # DWARF version number .byte 1 # DWARF Unit Type .byte 8 # Address Size (in bytes) .long .debug_abbrev # Offset Into Abbrev. Section .byte 1 # Abbrev [1] 0xc:0x7d DW_TAG_compile_unit .byte 0 # DW_AT_producer .short 29 # DW_AT_language .byte 1 # DW_AT_name .long .Lstr_offsets_base0 # DW_AT_str_offsets_base .long .Lline_table_start0 # DW_AT_stmt_list .byte 2 # DW_AT_comp_dir .byte 0 # DW_AT_low_pc .long .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc .long .Laddr_table_base0 # DW_AT_addr_base .long .Lloclists_table_base0 # DW_AT_loclists_base .byte 2 # Abbrev [2] 0x27:0x58 DW_TAG_subprogram .byte 0 # DW_AT_low_pc .long .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc .byte 1 # DW_AT_frame_base .byte 86 # DW_AT_call_all_calls .byte 3 # DW_AT_name .byte 0 # DW_AT_decl_file .byte 2 # DW_AT_decl_line # DW_AT_prototyped .long 127 # DW_AT_type # DW_AT_external .byte 3 # Abbrev [3] 0x36:0x9 DW_TAG_formal_parameter .byte 0 # DW_AT_location .byte 6 # DW_AT_name .byte 0 # DW_AT_decl_file .byte 2 # DW_AT_decl_line .long 127 # DW_AT_type .byte 3 # Abbrev [3] 0x3f:0x9 DW_TAG_formal_parameter .byte 1 # DW_AT_location .byte 7 # DW_AT_name .byte 0 # DW_AT_decl_file .byte 2 # DW_AT_decl_line .long 127 # DW_AT_type .byte 4 # Abbrev [4] 0x48:0xb DW_TAG_variable .byte 2 # DW_AT_location .byte 145 .byte 124 .byte 5 # DW_AT_name .byte 0 # DW_AT_decl_file .byte 3 # DW_AT_decl_line .long 131 # DW_AT_type .byte 5 # Abbrev [5] 0x53:0x9 DW_TAG_variable .byte 2 # DW_AT_location .byte 8 # DW_AT_name .byte 0 # DW_AT_decl_file .byte 4 # DW_AT_decl_line .long 127 # DW_AT_type .byte 5 # Abbrev [5] 0x5c:0x9 DW_TAG_variable .byte 3 # DW_AT_location .byte 9 # DW_AT_name .byte 0 # DW_AT_decl_file .byte 4 # DW_AT_decl_line .long 127 # DW_AT_type .byte 5 # Abbrev [5] 0x65:0x9 DW_TAG_variable .byte 4 # DW_AT_location .byte 10 # DW_AT_name .byte 0 # DW_AT_decl_file .byte 4 # DW_AT_decl_line .long 127 # DW_AT_type .byte 6 # Abbrev [6] 0x6e:0x10 DW_TAG_lexical_block .byte 1 # DW_AT_low_pc .long .Ltmp9-.Ltmp1 # DW_AT_high_pc .byte 5 # Abbrev [5] 0x74:0x9 DW_TAG_variable .byte 5 # DW_AT_location .byte 11 # DW_AT_name .byte 0 # DW_AT_decl_file .byte 6 # DW_AT_decl_line .long 127 # DW_AT_type .byte 0 # End Of Children Mark .byte 0 # End Of Children Mark .byte 7 # Abbrev [7] 0x7f:0x4 DW_TAG_base_type .byte 4 # DW_AT_name .byte 5 # DW_AT_encoding .byte 4 # DW_AT_byte_size .byte 8 # Abbrev [8] 0x83:0x5 DW_TAG_volatile_type .long 127 # DW_AT_type .byte 0 # End Of Children Mark .Ldebug_info_end0: .section .debug_str_offsets,"",@progbits .long 52 # Length of String Offsets Set .short 5 .short 0 .Lstr_offsets_base0: .section .debug_str,"MS",@progbits,1 .Linfo_string0: .asciz "clang version 22.0.0git (https://github.com/UltimateForce21/llvm-project.git 79c0a9e1e7da0f727c41d27c9c6ff8a28bb7d06f)" # string offset=0 .Linfo_string1: .asciz "loop_reg_rotate.c" # string offset=119 .Linfo_string2: .asciz "." # string offset=137 .Linfo_string3: .asciz "loop_reg_rotate" # string offset=139 .Linfo_string4: .asciz "int" # string offset=155 .Linfo_string5: .asciz "acc" # string offset=159 .Linfo_string6: .asciz "n" # string offset=163 .Linfo_string7: .asciz "seed" # string offset=165 .Linfo_string8: .asciz "i" # string offset=170 .Linfo_string9: .asciz "j" # string offset=172 .Linfo_string10: .asciz "k" # string offset=174 .Linfo_string11: .asciz "t" # string offset=176 .section .debug_str_offsets,"",@progbits .long .Linfo_string0 .long .Linfo_string1 .long .Linfo_string2 .long .Linfo_string3 .long .Linfo_string4 .long .Linfo_string5 .long .Linfo_string6 .long .Linfo_string7 .long .Linfo_string8 .long .Linfo_string9 .long .Linfo_string10 .long .Linfo_string11 .section .debug_addr,"",@progbits .long .Ldebug_addr_end0-.Ldebug_addr_start0 # Length of contribution .Ldebug_addr_start0: .short 5 # DWARF version number .byte 8 # Address size .byte 0 # Segment selector size .Laddr_table_base0: .quad .Lfunc_begin0 .quad .Ltmp1 .Ldebug_addr_end0: .ident "clang version 22.0.0git (https://github.com/UltimateForce21/llvm-project.git 79c0a9e1e7da0f727c41d27c9c6ff8a28bb7d06f)" .section ".note.GNU-stack","",@progbits .addrsig .section .debug_line,"",@progbits .Lline_table_start0: